ascorbic-acid and Diabetes-Mellitus

To investigate the associations between circulating micronutrients (vitamins A, C, D, E, and carotenoids) and risk of diabetic retinopathy (DR).. Cross-sectional study and meta-analysis.. The cross-sectional study included 517 diabetic participants aged ≥40 years in the 2005-2006 National Health and Nutrition Examination Survey. Serum vitamin D was converted to liquid chromatography-tandem mass spectrometry-equivalent results, while other micronutrients were measured using high-performance liquid chromatography. Presence of DR was determined based on non-mydriatic fundus photographs. A meta-analysis was subsequently performed, which included relevant studies published from January 01, 1990 to December 31, 2020.. Of the 517 included participants, DR was identified in 159 participants (25.17%). After adjusting for multiple confounders, only serum vitamin C was associated with a lower risk of DR (odds ratio [OR]: 0.60; 95% confidence interval [CI]: 0.38-0.95). A total of 35 studies were included in the subsequent meta-analysis. Comparing 1056 participants with DR to 920 controls, the pooled weighted mean difference (WMD) of vitamin C was -11.01 (95% CI: -19.35 to -2.67). Regarding vitamins D and E, the pooled WMD was -3.06 (95% CI: -5.15 to -0.96) and -3.03 (95% CI: -4.24 to -1.82), respectively. No associations were identified between DR and circulating vitamin A or carotenoids.. Lower levels of circulating vitamins C, D, and E were found in DR patients than those without. More high-quality studies are required to assess the real effects of micronutrients on DR.

Topics: Ascorbic Acid; Carotenoids; Cross-Sectional Studies; Diabetes Mellitus; Diabetic Retinopathy; Humans; Micronutrients; Nutrition Surveys; Risk Factors; Vitamins

The lifetime risk of developing a diabetic foot ulcer (DFU) in people with diabetes is as high as 25%. A trio of factors constitute the diabetic foot syndrome that characterises DFUs, including neuropathy, vascular disease and infections. Vitamin C has important functions in the nervous, cardiovascular, and immune systems that are implicated in DFU development. Furthermore, vitamin C deficiency has been observed in individuals with DFUs, suggesting an important function of vitamin C in DFU management and treatment. Therefore, this literature review evaluates the role of vitamin C in the nervous, cardiovascular and immune systems in relation to wound healing and DFUs, as well as discussing vitamin C's lesser known role in depression, a condition that affects many individuals with a DFU.. A literature search was done using PubMed, Cochrane Library, Embase, Ovid, Computer Retrieval of Information on Scientific Projects, and NIH Clinical Center. Search terms included 'diabetic foot ulcer,' 'diabetic foot,' 'vitamin C,' and 'ascorbic acid.'. Of the 71 studies initially identified, seven studies met the inclusion criteria, and only three were human clinical trials. Overall, the literature on this subject is limited, with mainly observational and animal studies, and few human clinical trials.. There is a need for additional human clinical trials on vitamin C supplementation in individuals with a DFU to fill the knowledge gap and guide clinical practice.

Topics: Animals; Ascorbic Acid; Diabetes Mellitus; Diabetic Foot; Humans; Vitamins; Wound Healing

For decades, there has been epidemiologic evidence linking chronic toxic metal exposure with cardiovascular disease, suggesting a therapeutic role for metal chelation. Given the lack of compelling scientific evidence, however, the indications for metal chelation were never clearly defined. To determine the safety and efficacy of chelation therapy, the National Institutes of Health funded the Trial to Assess Chelation Therapy (TACT). TACT was the first double-blind, randomized, controlled trial to demonstrate an improvement in cardiovascular outcomes with edetate disodium therapy in patients with prior myocardial infarction. The therapeutic benefit was striking among the prespecified subgroup of patients with diabetes.. We review the published literature focusing on the atherogenic nature of diabetes, as well as available evidence from clinical trials, complete and in progress, of metal chelation with edetate disodium therapy in patients with diabetes.. The TACT results support the concept that ubiquitous toxic metals such as lead and cadmium may be modifiable risk factors for cardiovascular disease, particularly in patients with diabetes.. The purpose of this review is to discuss the potential mechanisms unifying the pathogenesis of atherogenic factors in diabetes with toxic metal exposure, and the potential role of metal chelation.

Topics: Antioxidants; Arsenic; Ascorbic Acid; Atherosclerosis; Cadmium; Calcium Chelating Agents; Cardiovascular Diseases; Chelating Agents; Chelation Therapy; Copper; Diabetes Complications; Diabetes Mellitus; Edetic Acid; Glycation End Products, Advanced; Hospitalization; Humans; Iron; Lead; Lipid Metabolism; Mercury; Myocardial Infarction; Myocardial Revascularization; Oxidative Stress; Randomized Controlled Trials as Topic; Stroke

The beneficial role of the Mediterranean diet in the prevention of chronic diseases, including cardiovascular diseases, diabetes, and obesity, is well-recognized. In this context,

Topics: Ascorbic Acid; Biofortification; Brassicaceae; Cardiovascular Diseases; Carotenoids; Chronic Disease; Diabetes Mellitus; Glucosinolates; Humans; Hydroxybenzoates; Obesity; Phytochemicals; Vegetables

The role of vitamin C and vitamin E in the prevention and treatment of diseases is analyzed from the standpoint of evidence-based medicine. The high provision of a patient with the vitamins has a therapeutic and preventive impact on the development and course of a number of diseases. Furthermore, when additionally prescribing the vitamins as part of combination therapy, it is necessary to take into account possible drug interactions, including those due to the inducing effect of the above antioxidants on cytochrome P450 3A4.. Проанализирована роль витаминов С и Е в профилактике и терапии заболеваний с точки зрения доказательной медицины. Высокий статус по обеспеченности организма пациента витаминами оказывает лечебно-профилактическое действие на развитие и течение ряда заболеваний. Кроме того, при дополнительном назначении витаминов в составе комплексной терапии необходимо учитывать возможные межлекарственные взаимодействия, в том числе вследствие индуцирующего действия перечисленных антиоксидантов на цитохром Р450 3А4.

Topics: Ascorbic Acid; Cardiovascular Diseases; Diabetes Mellitus; Evidence-Based Medicine; Humans; Tocopherols; Vitamins

Diabetes is a chronic metabolic disorder that continues to present as a major health problem worldwide. It is characterized by absolute or relative deficiencies in insulin secretion and/or insulin action and is associated with chronic hyperglycemia and disturbances of carbohydrate, lipid, and protein metabolism. Many studies suggest a central role for oxidative stress in the pathogenesis of this multi-faceted metabolic disorder. This has prompted investigations in the use of antioxidants as a complementary therapeutic approach. In this review we briefly summarize oxidative mechanisms implicated in diabetic complications and then focus on the findings resulting from human clinical trials where antioxidants were studied as an adjuvant to standard diabetes treatment during the last ten years. A literature search using PubMed (last ten years) was performed using the following terms: vitamin E, vitamin C, coenzyme Q10, alpha lipoic acid, L-carnitine, ruboxistaurin or LY 333531 and diabetes. This search was limited to human clinical trials. We concluded there is not any established benefit for antioxidants use in the management of diabetic complications. Therefore, routine vitamin or mineral supplementation is not generally recommended.

Topics: Antioxidants; Ascorbic Acid; Carnitine; Clinical Trials as Topic; Diabetes Complications; Diabetes Mellitus; Diabetes Mellitus, Type 2; Female; Humans; Indoles; Male; Maleimides; Oxidative Stress; Thioctic Acid; Treatment Outcome; Ubiquinone; Vitamins

Reactive oxygen species (ROS) have deleterious or beneficial effects; this dual nature of ROS means that ROS act as intracellular signaling molecules and as defense mechanisms against micro-organisms. An overproduction of ROS results in oxidative stress, a deleterious process that damages cell structures, including lipids, proteins, and DNA. Oxidative stress plays a major role in various human disease states, including endocrine dysfunction. As a safeguard against oxidative stress, several endogenous nonenzymatic and enzymatic antioxidant systems exist. Antioxidants can delay or prevent oxidative stress and are widely used in the hope of maintaining health and preventing diseases. Although early studies suggested that antioxidant supplements promoted health, later clinical trials revealed that it may not be true in all cases. In this article, we provide a brief review of the pathophysiologic aspects of oxidative stress in a number of the most commonly human endocrionopathies (diabetes, male and female infertility and thyroid diseases) and review the therapeutic potentials of existing antioxidant strategies. We focus on human clinical trials and discuss the implications of their results. Based on the data reported so far, we conclude that the results reported challenge us to design better antioxidant trials in future, with a particular emphasis on identifying 1) appropriate doses 2) selecting the right populations 3) treating for optimal durations and 4) specific intracellular targeting mechanisms.

Topics: Antioxidants; Ascorbic Acid; Diabetes Mellitus; Female; Humans; Infertility; Male; Oxidative Stress; Reactive Oxygen Species; Thioctic Acid; Thyroid Diseases; Ubiquinone; Vitamin E

For more than 50 years, the Food and Nutrition Board of the National Academy of Sciences has been reviewing nutrition research and defining nutrient requirements for healthy people, referred to as the Recommended Dietary Allowances (RDA). As new nutrition research is published, the importance of vitamins as vital nutrients is underscored, and new physiologic roles and applications to human health are examined and considered with regard to updating the RDA. Each year a substantial amount of new research is published on vitamins. This review examines recent research published on the importance of vitamin C with regard to general health.

Topics: Antioxidants; Ascorbic Acid; Ascorbic Acid Deficiency; Asthma; Cardiovascular Diseases; Diabetes Mellitus; Exercise; Humans; Hypersensitivity; Neoplasms

This review gives a brief overview of the main types of dementia and summarizes current thinking on the relationship between nutritional-related factors and disorders, and dementia. Dementia is a multi-factor pathological condition, and nutrition is one factor that may play a role on its onset and progression. An optimal intake of nutrients doesn't protect people from dementia. However, studies in this area show that inadequate dietary habits, which are of particular concern in elderly populations, may increase the risk of developing a number of age-related diseases, including disorders of impaired cognitive function. They show that a deficiency in essential nutrients, such as certain B complex vitamins, can result in hyperhomocysteinemia, a well-known risk factor for atherosclerosis and recently associated with cognitive impairment in old age. A deficiency of antioxidants such as vitamins C and E, and beta-carotene, as well as nutrition-related disorders like hypercholesterolemia, hypertension, and diabetes, may also have some role in cognitive impairment. These factors can be present for a long time before cognitive impairment becomes evident, therefore they could be potentially detected and corrected in a timely manner.

Topics: Alzheimer Disease; Antioxidants; Ascorbic Acid; Dementia; Diabetes Mellitus; Diet; Humans; Hyperhomocysteinemia; Hyperlipidemias; Hypertension; Nutrition Disorders; Nutritional Physiological Phenomena; Oxidative Stress; Risk Factors; Vitamin A; Vitamin B Complex; Vitamin E

Vitamins are essential to maintain normal metabolic processes and homeostasis within the body. The amount of a specific vitamin required by an individual varies considerably and it is influenced by such factors as body size, growth rate, physical activity, and pregnancy. Most vitamins are stored minimally in human cells, but some are stored in liver cells to a greater extent. Vitamins A and D, for example, may be stored in sufficient amounts to maintain an individual without any intake for 5 to 10 months and 2 to 4 months, respectively. However, a deficiency of vitamin B compounds (except vitamin B12) may be noted within days, and the lack of vitamin C will manifest within weeks and may result in death in 5 to 6 months. The current recommended dietary allowance (RDA) of vitamin C is 75 mg for woman and 90 mg for men, based on the vitamin's role as an antioxidant as well as protection from deficiency. High intakes of the vitamin are generally well tolerated, however, a Tolerable Upper Level (TUL) was recently set at 2 g based on gastrointestinal upset that sometimes accompanies excessive dosages. Several populations warrant special attention with respect to vitamin C requirements. These include patients with periodontal disease, smokers, pregnant and lactating women, and the elderly.

Topics: Alzheimer Disease; Animals; Antioxidants; Ascorbic Acid; Ascorbic Acid Deficiency; Bone Regeneration; Cardiovascular Diseases; Chondrogenesis; Diabetes Mellitus; Female; Humans; Male; Maximum Tolerated Dose; Nutrition Policy; Periodontal Diseases; Pregnancy; Virus Diseases

Topics: Animals; Antioxidants; Ascorbic Acid; Diabetes Complications; Diabetes Mellitus; Humans; Oxidative Stress; Vitamin E

In previous minireviews in this journal, we discussed work on induction of tetrahydrobiopterin biosynthesis by cytokines and its significance for nitric oxide (NO) production of intact cells as well as functions of H4-biopterin identified at this time for NO synthases (Proc Soc Exp Biol Med 203: 1-12, 1993; Proc Soc Exp Biol Med 219: 171-182, 1998). Meanwhile, the recognition of the importance of tetrahydrobiopterin for NO formation has led to new insights into complex biological processes and revealed possible novel pharmacological strategies to intervene in certain pathological conditions. Recent work could also establish that tetrahydrobiopterin, in addition to its allosteric effects, is redox-active in the NO synthase reaction. In this review, we summarize the current view of how tetrahydrobiopterin functions in the generation of NO and focus on pharmacological aspects of tetrahydrobiopterin availability with emphasis on endothelial function.

Topics: Allosteric Regulation; Animals; Ascorbic Acid; Biopterins; Catalysis; Diabetes Mellitus; Electron Transport; Endothelium, Vascular; Enzyme Inhibitors; Humans; Models, Biological; Nitric Oxide; Nitric Oxide Synthase; Vasodilation

Dehydroascorbic acid (DHA) is abundant in the human diet and also is generated from vitamin C (ascorbic acid, AA) in the lumen of the gastrointestinal tract. DHA is absorbed from the lumen of the small intestine and reduced to AA, which subsequently circulates in the blood. Utilization of AA as an antioxidant and enzyme cofactor causes its oxidation to DHA in extracellular fluid and cells. DHA has an important role in many cell types because it can be used to regenerate AA. Both physiological (e.g. insulin, insulin-like growth factor I, cyclic AMP) and pathological (e.g. oxidative stress, diabetes, sepsis) factors alter the transport and metabolic mechanisms responsible for this DHA recycling.

Topics: Animals; Ascorbic Acid; Biological Transport; Dehydroascorbic Acid; Diabetes Mellitus; Humans; Inflammation; Oxidation-Reduction; Reperfusion Injury; Sepsis

Diabetes mellitus is a chronic disease associated with serious complications. A number of studies have suggested that enhanced oxidation is the underlying abnormality responsible for some of the complications of diabetes. It is not known whether the ingestion of antioxidant vitamins could retard or perhaps reverse the oxidative damage. The information regarding the benefit of antioxidant vitamin supplementation is conflicting some trials have demonstrated adverse effects of excessive consumption of vitamin supplements. In this article, we review the available literature on the association of cardiovascular events and ingestion of vitamins with antioxidant properties. Given the lack of data to substantiate the benefit and safety of ingestion of antioxidant vitamins in excess of the recommended dietary allowance, physicians should avoid the recommendation of vitamin supplementation to their patients.

Topics: Antioxidants; Ascorbic Acid; Carotenoids; Diabetes Mellitus; Humans; Oxidative Stress; Retinoids; Vitamin E; Vitamins

Oxidation is a biochemical process of loss of electrons associated with another of reception called reduction. This process is capital for life, because it takes part in the production of cellular energy. Oxidative stress appears when oxidation is excessive. This reality is complex in all biological levels, and cannot be measured or defined by a single parameter. A great number of diseases have been related to oxidative stress and generation of free radicals. For this reason, antioxidant therapies and diets (such as mediterranean diet) rich or enriched with antioxidants seem to prevent or at least to attenuate the organic deterioration originated by an excessive oxidative stress.

Topics: Acute Kidney Injury; Aged; Aging; Antioxidants; Arteriosclerosis; Ascorbic Acid; beta Carotene; Cataract; Diabetes Mellitus; Diet; Humans; Hypertension; Liver Diseases; Neoplasms; Oxidation-Reduction; Oxidative Stress; Primary Prevention; Risk Factors; Selenium; Vitamin E

The plasma vitamin levels are discussed in association with human diabetic condition. 1) Plasma vitamin B1 level of diabetic patients is revealed in the state of marginal deficiency. 2) Vitamin B6, as the coenzyme pyridoxal phosphate, plays an important role in the metabolism of carbohydrates, therefore B6 has been associated with impairments in gluconeogenesis and abnormal glucose intolerance. 3) Vascular complications of diabetes mellitus, such as atherosclerosis and retinopathy are considered to be related with glycation of low density lipoprotein which induces oxidative injuries to vascular endothelium. Administration of vitamins to diabetic patients reduces insulin requirement and attracts much attention for improvement of vascular complications. Vitamins play as not only nutritional supplements for deficiency, but pharmacological agents for treatment.

Topics: Ascorbic Acid; Diabetes Mellitus; Humans; Thiamine; Vitamin B 12; Vitamin E

Considerable interest has risen in the idea that oxidative stress is instrumental in the etiology of numerous human diseases. Oxidative stress can arise through the increased production of reactive oxygen species (ROS) and/or because of a deficiency of antioxidant defenses. Antioxidant deficiencies can develop as a result of decreased antioxidant intake (such as vitamins C and E), synthesis of enzymes (such as superoxide dismutase and glutathione peroxidase) or increased antioxidant utilization. Insufficient antioxidant enzyme synthesis may in turn be due to decreased micronutrient availability (such as selenium, magnese, copper and zinc). Of those diseases linked with oxidative stress, cardiovascular disease provides the strongest evidence for the protective role of antioxidants. A high consumption of fruit and vegetables, which are good sources of antioxidants, is associated with a lower coronary risk. More specifically, there is evidence of a reduced coronary risk in populations with high blood levels of the antioxidant nutrients, vitamins C and E. Evidence is also accumulating that diabetes, and microvascular complications associated with diabetes, involve oxidative stress and have compromised antioxidant status. In addition, patients who develop acute respiratory distress syndrome (ARDS) also exhibit clear evidence of oxidative stress. Definitive proof for active oxygen formation and oxidative cell damage being causative rather than a result of other underlying these pathologies remains elusive; however, evidence is sufficiently compelling to suggest that antioxidants are potential therapeutic agents in the above conditions.

Topics: Antioxidants; Ascorbic Acid; beta Carotene; Cardiovascular Diseases; Diabetes Mellitus; Humans; Oxidative Stress; Respiratory Distress Syndrome; Vitamin E

Topics: Animals; Ascorbic Acid; Diabetes Mellitus; Gastrointestinal Diseases; Humans

Topics: Animals; Antioxidants; Ascorbic Acid; Diabetes Complications; Diabetes Mellitus; Glucose; Glycosylation; Humans; Iron; Oxidants; Oxidation-Reduction; Oxidative Stress; Proteins; Scurvy

This paper reviews the scientific evidence regarding the vitamin C status of people with diabetes mellitus and whether they might have increased dietary vitamin C requirements. English language articles published from 1935 to the present that either compare ascorbic acid concentrations of persons with and without diabetes mellitus or assess the impact of vitamin C supplementation on various health outcomes among persons with diabetes mellitus were examined. Most studies have found people with diabetes mellitus to have at least 30% lower circulating ascorbic acid concentrations than people without diabetes mellitus. Vitamin C supplementation had little impact on blood glucose concentrations, but was found to lower cellular sorbitol concentrations and to reduce capillary fragility. Much of the past research in this area has been methodologically weak. To further understand the relation of ascorbic acid and diabetes mellitus, randomized clinical trials of ascorbic acid supplementation should be a high priority for research.

Topics: Ascorbic Acid; Diabetes Mellitus; Food, Fortified; Health Status; Humans

Free radical mechanisms are increasingly being implicated in the pathogenesis of tissue damage in diabetes. Various sources of free radicals may modulate oxidative stress in diabetes, including non-enzymatic glycosylation of proteins and monosaccharide autooxidation, polyol pathway activity, indirect production of free radicals through cell damage from other causes, and reduced antioxidant reserve. Ascorbic acid, which may be a principal modulator of free radical activity in diabetes, is shown to be consumed, presumably through free radical scavenging, thus preserving levels of other antioxidants such as glutathione.

Topics: Animals; Antioxidants; Ascorbic Acid; Diabetes Mellitus; Diabetes Mellitus, Experimental; Free Radical Scavengers; Free Radicals; Glycosylation; Humans; Models, Biological; Sorbitol

The concept that ascorbic acid (vitamin C) supplementation protects against coronary heart disease developed in the late 1970s when vitamin C intakes in industrialized nations were lower than at present. Supplementation was then shown to lower plasma total cholesterol and, among some elderly men, to raise high-density lipoprotein cholesterol. However, among people in initially good vitamin C nutriture, these effects are usually not seen. In five populations of essentially healthy people, blood pressure has been found to correlate negatively with vitamin C status. Recently, in a placebo-controlled, double-blinded study, extra ascorbic acid for 6 wk was observed to lower systolic and pulse pressure in a small group of borderline hypertensive subjects.

Topics: Age Factors; Ascorbic Acid; Blood Pressure; Cholesterol; Cholesterol, HDL; Coronary Disease; Diabetes Mellitus; Humans; Risk Factors; Sex Factors; Smoking

Topics: Ascorbic Acid; Ascorbic Acid Deficiency; Diabetes Mellitus; Drug Synergism; Drug Therapy, Combination; Humans; Hyperglycemia; Hypoglycemic Agents; Insulin

Topics: Animals; Ascorbic Acid; Cholesterol; Diabetes Mellitus; Guinea Pigs; Humans; Nutritional Physiological Phenomena; Nutritional Requirements

Topics: Animals; Ascorbic Acid; Aspartic Acid; Biological Evolution; Dehydroascorbic Acid; Diabetes Mellitus; Guinea Pigs; Histamine; Humans; Kidney; Liver; Microsomes; Organ Specificity; Rats; Scurvy; Species Specificity

Topics: Adrenalectomy; Animals; Anti-Bacterial Agents; Ascorbic Acid; Blood Glucose; Chelating Agents; Chemical Phenomena; Chemistry; Diabetes Mellitus; Diet; Drug Antagonism; Drug Synergism; Glucose; Hypophysectomy; Insulin; Islets of Langerhans; Liver Glycogen; Rabbits; Rats; Thiocarbamates; Tolbutamide; Uric Acid

The current study assesses the effects of platelet-rich plasma-fibrin glue (PRP-FG) dressing along with oral vitamin E and C on wound healing and biochemical markers in patients with non-healing diabetic foot ulcers (non-healing DFU).. This randomized controlled trial was performed on 25 patients with non-healing DFU. Patients were treated with PRP-FG dressing plus oral vitamin E and C (intervention group) or PRP-FG dressing plus placebo (control group) for 8 weeks.. Eight weeks after treatment, six wounds in the intervention group and two wounds in the control group were completely closed, and also wound size significantly reduced in both intervention and control groups (. Our results showed that PRP-FG dressing along with oral vitamin E and C could be used to increase wound healing in patients with non-healing DFU by enhancing the wound healing process and reducing oxidative stress.. This trial is registered at ClinicalTrials.gov (CT.gov identifier: NCT04315909).

Topics: Ascorbic Acid; Bandages; Diabetes Mellitus; Diabetic Foot; Double-Blind Method; Fibrin Tissue Adhesive; Humans; Platelet-Rich Plasma; Vitamin E

Contrast-induced nephropathy (CIN) is a leading cause of hospital-acquired renal failure and affects mortality and morbidity. There has been no study comparing the efficacy of N-acetylcysteine (NAC) and ascorbic acid that have potential for CIN prevention in patients with renal insufficiency.. We conducted a prospective randomized controlled trial. A total of 212 patients who had pre-existing renal impairment with basal creatinine clearance < or =60 mL/min and/or serum creatinine (SCr) level of > or =1.1 mg/dL, were randomized to have either high-dose NAC (1,200 mg orally twice a day before and on the day of coronary catheterization, n = 106) or ascorbic acid (3 g and 2 g orally before, and 2 g twice after coronary catheterization with a 12-hour interval, n = 106). The primary end point was the maximum increase of SCr level, and the secondary end point was the incidence of CIN.. The maximum increase of SCr level was significantly lower in NAC group than in ascorbic acid group as follows: -0.03 +/- 0.18 mg/dL versus 0.04 +/- 0.20 mg/mL, respectively (P = .026). Patients with diabetes or who had received a high dose of contrast media experienced significantly less rise of SCr level with NAC than ascorbic acid; in diabetic subgroup, -0.05 +/- 0.22 mg/dL versus 0.09 +/- 0.29 mg/mL, respectively (P = .020); in patients with high dose of dye, -0.03 +/- 0.17 mg/dL versus 0.04 +/- 0.21 mg/mL, respectively (P = .032). The incidence of CIN, the secondary end point, tended to be in favor of NAC rather than ascorbic acid, 1.2% versus 4.4%, respectively (P = .370). Notably, among the diabetes patients, the NAC significantly lowered CIN rate than ascorbic acid, 0% (0/38) versus 12.5% (4/32), respectively (P = .039).. High-dose NAC seems more beneficial than ascorbic acid in preventing contrast-induced renal function deterioration in patients, especially diabetic patients, with renal insufficiency undergoing coronary angiography.

Topics: Acetylcysteine; Aged; Antioxidants; Ascorbic Acid; Comorbidity; Contrast Media; Coronary Angiography; Creatinine; Diabetes Mellitus; Female; Free Radical Scavengers; Humans; Male; Middle Aged; Prospective Studies; Renal Insufficiency

Plasma vitamin A, C and E levels and erythrocyte antioxidant enzyme activities were investigated in type I and type II diabetic subjects with and without complications, i.e., hypertension, coronary artery disease and renal failure. Reverse phase HPLC was used to quantify vitamin A and E levels. We observed that the vitamin C levels were not significantly different between control and diabetic subjects. However, vitamin A and E levels were significantly lower in type I and type II diabetic subjects compared to controls. Superoxide dismutase (SOD) activity was significantly lower in type II, but not in type I, diabetic patients compared to controls. Interestingly, glutathione reductase and peroxidase activities were diminished in type I, but not in type II, diabetic subjects as compared to controls. Catalase activity was lower in both types of diabetic patients in comparison with their respective controls. Altogether these results suggest that diabetes mellitus may be associated with altered antioxidant status regardless to various complications.

Topics: Adult; Antioxidants; Ascorbic Acid; Catalase; Chromatography, High Pressure Liquid; Coronary Artery Disease; Diabetes Complications; Diabetes Mellitus; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Erythrocytes; Female; Glutathione Peroxidase; Glutathione Reductase; Humans; Hypertension; Male; Middle Aged; Renal Insufficiency; Superoxide Dismutase; Vitamin A; Vitamin E; Vitamins

It has been suggested that increased intake of various antioxidant vitamins reduces the incidence rates of vascular disease, cancer, and other adverse outcomes.. 20,536 UK adults (aged 40-80) with coronary disease, other occlusive arterial disease, or diabetes were randomly allocated to receive antioxidant vitamin supplementation (600 mg vitamin E, 250 mg vitamin C, and 20 mg beta-carotene daily) or matching placebo. Intention-to-treat comparisons of outcome were conducted between all vitamin-allocated and all placebo-allocated participants. An average of 83% of participants in each treatment group remained compliant during the scheduled 5-year treatment period. Allocation to this vitamin regimen approximately doubled the plasma concentration of alpha-tocopherol, increased that of vitamin C by one-third, and quadrupled that of beta-carotene. Primary outcomes were major coronary events (for overall analyses) and fatal or non-fatal vascular events (for subcategory analyses), with subsidiary assessments of cancer and of other major morbidity.. There were no significant differences in all-cause mortality (1446 [14.1%] vitamin-allocated vs 1389 [13.5%] placebo-allocated), or in deaths due to vascular (878 [8.6%] vs 840 [8.2%]) or non-vascular (568 [5.5%] vs 549 [5.3%]) causes. Nor were there any significant differences in the numbers of participants having non-fatal myocardial infarction or coronary death (1063 [10.4%] vs 1047 [10.2%]), non-fatal or fatal stroke (511 [5.0%] vs 518 [5.0%]), or coronary or non-coronary revascularisation (1058 [10.3%] vs 1086 [10.6%]). For the first occurrence of any of these "major vascular events", there were no material differences either overall (2306 [22.5%] vs 2312 [22.5%]; event rate ratio 1.00 [95% CI 0.94-1.06]) or in any of the various subcategories considered. There were no significant effects on cancer incidence or on hospitalisation for any other non-vascular cause.. Among the high-risk individuals that were studied, these antioxidant vitamins appeared to be safe. But, although this regimen increased blood vitamin concentrations substantially, it did not produce any significant reductions in the 5-year mortality from, or incidence of, any type of vascular disease, cancer, or other major outcome.

Topics: Adult; Aged; Aged, 80 and over; Antioxidants; Ascorbic Acid; beta Carotene; Cardiovascular Diseases; Cause of Death; Cholesterol; Coronary Disease; Diabetes Mellitus; Female; Follow-Up Studies; Humans; Male; Middle Aged; Neoplasms; Severity of Illness Index; Stroke; United Kingdom; Vitamin E

Topics: Administration, Oral; Adult; Ascorbic Acid; Blood Glucose; Brachial Artery; Diabetes Mellitus; Diabetes, Gestational; Double-Blind Method; Endothelium, Vascular; Female; Humans; Obesity; Postpartum Period; Vasodilation

In order to confirm the effect of ascorbic acid (AA) on human erythrocyte sorbitol accumulation and explore its mechanism of action, the effects of ascorbic acid in vitro on the sorbitol (S) and glucose (EG) content of human erythrocytes and in particular on the S/EG ratio as a marker of aldose reductase (AR) activity were carefully observed. The results showed that both the accumulation of erythrocyte sorbitol and the S/EG ratio were strongly reduced by the addition of AA. The sorbitol content in the erythrocyte and the S/EG ratio were reduced by a maximum of 87.3% and 83.4% and 93.8% and 63.9% when the medium's AA concentration was at its peak with 5.6 mmol/l and 28 mmol/l glucose in the medium, respectively. The contents of erythrocyte glucose measured coincidentally revealed a positive correlation with the ascorbic acid concentration in the medium during incubation in 5.6 mmol/l glucose while at a higher glucose level (28 mmol/l) in the medium the correlation became negative. These results suggested that the polyol pathway could be inhibited effectively by AA through its direct action on AR. The results of a double-blind cross-over trial using AA tablets or inositol tablets in eight diabetic patients showed that the supplementation of 1000 mg AA/day for 2 weeks resulted in reductions of 12.2% and 21.8% in erythrocyte sorbitol and red cell sorbitol/plasma glucose (S/PG) ratio, respectively (P < 0.05), whereas the fasting plasma glucose levels measured coincidentally revealed no changes (P > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Adolescent; Adult; Ascorbic Acid; Blood Glucose; Child; Diabetes Mellitus; Erythrocytes; Female; Humans; In Vitro Techniques; Male; Middle Aged; Reference Values; Regression Analysis; Sorbitol

The effect of magnesium (Mg) and ascorbic acid (AA) supplementation on metabolic control was assessed in 56 outpatient diabetics. A 90-day run-in period was followed by two 90-day treatment periods, during which Mg (600 mg/day) and AA (2 g/day) were administered in a randomized double-blind cross-over fashion. A decrease in systolic and diastolic blood pressure (132 +/- 3 vs. 138 +/- 4 and 77 +/- 2 vs. 82 +/- 2 mm Hg; p < 0.05) was observed in insulin-dependent diabetes mellitus subjects during Mg supplementation. No beneficial effect of Mg supplementation was observed on glycemic control, lipids or blood pressure in non-insulin-dependent diabetes mellitus (NIDDM) subjects. AA supplementation improved glycemic control among NIDDM subjects and both fasting blood glucose (9.1 +/- 0.5 vs. 10.1 +/- 0.6 mmol/l; p < 0.05) and HbA1c (8.5 +/- 0.3 vs. 9.3 +/- 0.3%; p < 0.05) improved. Beneficial effects of AA supplementation on cholesterol (5.9 +/- 0.2 vs. 6.2 +/- 0.2 mmol/l; p < 0.05) and triglycerides (2.2 +/- 0.2 vs. 2.5 +/- 0.2; p < 0.05) were also observed in NIDDM subjects. The results suggest that high-dose AA supplementation may have a beneficial effect in NIDDM subjects on both glycemic control and blood lipids.

Topics: Adult; Ascorbic Acid; Blood Glucose; Blood Pressure; Cross-Over Studies; Diabetes Mellitus; Diabetes Mellitus, Type 1; Diabetes Mellitus, Type 2; Double-Blind Method; Humans; Lipids; Magnesium; Middle Aged

A significantly lower vitamin C concentration has been found in the blood and particularly in the leukocytes of hypercholesterolemic diabetic patients than of healthy blood donors. Ascorbic acid administered in a dose of 500 mg per day for 12 months to metabolically stabilized hypercholesterolemic subjects with maturity-onset diabetes mellitus (diabetic diet without insulin or diabetic drugs) brought about a striking decline of cholesterolemia and a moderate decline of triglyceridemia. The serum lipid level in the control group given placebo remained unaltered. A daily administration of 500 mg of ascorbic acid for six months failed to affect the fasting level of serum immunoreactive insulin. It is assumed that the long-term administration of ascorbic acid to maturity-onset diabetics removed the tissue ascorbate deficiency and improved the liver ability to compensate the increased endogenous synthesis of cholesterol by its enhanced transformation to bile acids.

Topics: Ascorbic Acid; Ascorbic Acid Deficiency; Cholesterol; Clinical Trials as Topic; Diabetes Complications; Diabetes Mellitus; Female; Humans; Hypercholesterolemia; Leukocytes; Male; Middle Aged; Placebos; Triglycerides

Topics: Adult; Aged; Ascorbic Acid; Capillary Fragility; Diabetes Mellitus; Diabetic Retinopathy; Diet Therapy; Humans; Middle Aged; Placebos; Pressure; Time Factors

Di-(2-ethylhexyl)-phthalate (DEHP), a common Phthalic acid ester (PAEs), has been reported to be associated with diabetes mellitus, yet the underlying mechanisms remain unknown. Combined nutrient interventions have been shown to alleviate the diabetic toxicity of DEHP. However, the effects and mechanisms of the combined intervention of Astragalus and vitamins (C and E) are currently unknown. In this study, we investigated the potential mechanisms of DEHP-induced diabetes mellitus through transcriptome analysis and vitro experiments using rat insulinoma cells (INS-1 cells). Furthermore, we explored the protection of the combined Astragalus, vitamin C, and vitamin E on DEHP-induced diabetes mellitus through these mechanisms. INS-1 cells in the logarithmic growth period were exposed to 125 umol/L DEHP followed by high-throughput sequencing analysis. The cell proliferation inhibition rate was determined using MTT assay for each group, and the cell apoptosis rate and intracellular ROS level were measured using flow cytometer. Finally, insulin levels and markers of oxidative stress were detected using ELISA kits in different groups. A total of 372 differentially expressed genes were found between the 125 umol/L DEHP and control groups, subsequent functional enrichment analyses indicated that DEHP induced oxidative stress and disturbed insulin levels. In INS-1 cells, the rate of cell proliferation inhibition, apoptosis, and the degree of oxidative stress increased concentration-dependently with increasing DEHP concentrations, while antioxidant intervention could reverse these changes. Insulin synthesis and secretion decreased after 240 μmol/L DEHP exposure stimulated by 25 mM glucose in INS-1 cells, also could antioxidant intervention alleviate these reductions. Based on these results, the underlying mechanism of DEHP impairing the function of INS-1 cells might be through apoptosis pathways induced by oxidative stress and direct reduction of insulin levels (both synthesis and secretion), while the optimal combination of Astragalus and vitamins (C and E) could exert an alleviating effect.

Topics: Animals; Antioxidants; Ascorbic Acid; Diabetes Mellitus; Diethylhexyl Phthalate; Insulin; Insulinoma; Oxidative Stress; Pancreatic Neoplasms; Rats; Vitamin E; Vitamins

The drugs containing nitrates like isosorbide dinitrate, isosorbide mononitrate and glyceryl trinitrate, etc., trigger the oxidation of hemoglobin which is manifested in the pathological disorder named methemoglobinemia. It was considered interesting to investigate the preventive roles of vitamin C towards the toxic effects of nitrate containing drugs used for the treatment of angina. The aim is to find whether these drugs need to be administered with special care to diabetic patients who are more prone to develop methemoglobinemia. Vitamin C (500 mg/day) was administered orally to reduce the methemoglobin (metHb) level in both the diabetic and nondiabetic patients consuming nitrate containing drugs regularly, keeping diabetic and nondiabetic patients not on nitrate drugs as control. Concentration of metHb and hemoglobin A (HbA) was estimated spectrophotometrically assuming the molar extinction coefficient values of metHb as 3.78 mM

Topics: Ascorbic Acid; Diabetes Mellitus; Humans; Methemoglobinemia; Nitrates

Topics: Ascorbic Acid; Diabetes Mellitus; Humans; Kidney; Vitamins

Diabetes is associated with low plasma vitamin C concentrations.. We investigated the contribution of dysregulated vitamin C renal physiology, its prevalence, and associated clinical characteristics.. An essential prerequisite was determination of normal vitamin C renal threshold, the plasma concentration at which vitamin C first appears in urine. Using data from 17 healthy participants who underwent vitamin C depletion-repletion studies with a vitamin C dose range of 15-1250 mg daily, renal threshold was estimated using physiology-based pharmacokinetics modeling. Applying renal threshold 95% CIs, we estimated the minimal elimination threshold, the plasma concentration below which no vitamin C was expected in urine of healthy people. Renal leak was defined as abnormal presence of vitamin C in urine with plasma concentrations below the minimal elimination threshold. Criteria were tested in a cross-sectional cohort study of individuals with diabetes (82) and nondiabetic controls (80) using matched plasma and urine samples.. Vitamin C renal thresholds in healthy men and women were [mean (SD)] 48.5 (5.2) µM and 58.3 (7.5) µM, respectively. Compared with nondiabetic controls, participants with diabetes had significantly higher prevalence of vitamin C renal leak (9% compared with 33%; OR: 5.07; 95% CI: 1.97, 14.83; P < 0.001) and 30% lower mean plasma vitamin C concentrations (53.1 µM compared with 40.9 µM, P < 0.001). Fasting plasma glucose, glycosylated hemoglobin A1c, BMI, micro/macrovascular complications, and protein/creatinine ratio were predictive of vitamin C renal leak.. Increased prevalence of vitamin C renal leak in diabetes is associated with reduced plasma vitamin C concentrations. Glycemic control, microvascular complications, obesity, and proteinuria are predictive of renal leak.

Topics: Adult; Ascorbic Acid; Cross-Sectional Studies; Diabetes Mellitus; Diabetes Mellitus, Type 2; Diabetic Nephropathies; Female; Glycated Hemoglobin; Humans; Male; Middle Aged; Prevalence

The chronic administration of vitamin C and E can differentially disrupt hepatic insulin molecular pathway in rats. Hence, this study evaluated their effects on lipogenesis in the liver and adipose tissue and investigated the possible involvement of microRNA (miR)-22/29a/27a in the induced impaired glucose tolerance.. Wistar rats were orally supplemented with vitamin C (100, 200, and 500 mg/kg) or vitamin E (50, 100, and 200 mg/kg) for eight months.. Vitamin C or E at the highest doses significantly altered liver weight and index, serum and hepatic lipids, adiponectin, and liver enzymes; besides their reported unfavorable effect on glucose homeostasis. Vitamin C and E negatively affected peroxisome proliferator-activated receptor coactivator-1 (PGC-1α), sterol regulatory element-binding protein (SREBP)-1c/-2, miR-22/29a/27a expression, and adipose perilipin 1 to different extents, effects that were supported by the histopathological examination.. The current study provides a deeper insight into the findings of our previous study and highlights the detrimental effects of chronic vitamins supplementation on lipid metabolism. Overall, these findings emphasize the damage caused by the mindless use of supplements and reinforce the role of strict medical monitoring, particularly during the new COVID-19 era during which numerous commercial supplements are claiming to improve immunity.

Topics: Adipose Tissue; Animals; Ascorbic Acid; COVID-19; Diabetes Mellitus; Dietary Supplements; Lipid Metabolism; Liver; MicroRNAs; Rats; Rats, Wistar; Sterol Regulatory Element Binding Protein 1; Vitamin E; Vitamins

Population studies have shown a trend in decreasing vitamin C status and increasing prevalence of osteoporosis in patients with diabetes and non-diabetic people. Dietary vitamin C consumption is linked to improvement in bone mineral density (BMD) in epidemiological studies. VCAM-1 and adiponectin are known to activate osteoclasts, which increase bone loss.. This study examined whether there is any association between the circulating level of vitamin C and BMD and whether the beneficial effect of vitamin C on BMD was linked to a simultaneous decrease in circulating levels of adiponectin and VCAM-1 in subjects with diabetes.. Patients with diabetes (T2D,. Patients with diabetes had lower levels of vitamin C and higher levels of VCAM-1 and inflammatory cytokines. There was a significant positive association between vitamin C blood levels and lumbar spine BMD as well as a significant negative association between total adiponectin and VCAM-1 levels with that of vitamin C and lumbar BMD in patients with diabetes. Total adiponectin and VCAM-1 also showed a negative association with BMD of both the right and left femurs. The inter-relationship among the circulating levels of vitamin C and VCAM-1 and BMD was strong and is a novel finding.. This study reports a positive association of circulating vitamin C levels and the BMD and that the beneficial effects of vitamin C on BMD could be linked to a simultaneous lowering in circulating VCAM-1 and total adiponectin levels. Thus, dietary vitamin C consumption has potential to lower inflammation and the risk of osteoporosis in subjects with diabetes.

Topics: Absorptiometry, Photon; Adiponectin; Ascorbic Acid; Biomarkers; Bone Density; Cytokines; Diabetes Mellitus; Humans; Inflammation; Lumbar Vertebrae; Osteoporosis; Vascular Cell Adhesion Molecule-1; Vitamins

The present study was aimed to investigate the comparative antidiabetic potential of Nigella sativa seed extract and oil in an in vivo trial using rat animal model. The levels of antioxidants analysed in this study included catalase, vitamin C and bilirubin. NS methanolic extract and its oil were tested for their hypoglycemic effect against alloxanized diabetic rabbits (120mg/kg). The crude methanolic extract and the oil (2.5ml/kg/day) were given orally for 24 days that resulted in a significant reduction in glycaemia, particularly during the first 12 days of treatment (reductions of 58.09% and 73.27%, respectively), whereas the oil treated group normalised the levels of catalase (-69.23%), vitamin C (27.30%) and bilirubin (-51.48%) and the extract treated group normalised the levels of catalase (-65.38), vitamin C (24.15%) and bilirubin (-26.19%) at the end of the trial. The results have shown that the seed oil more significantly normalized the levels of serum catalase, serum ascorbic acid and total serum bilirubin as compared to the methanolic extract of Nigella sativa, so Nigella sativa seed oil (NSO) may be used as part of antidiabetic remedies against diabetes and utilized as a nutraceutical.

Topics: Animals; Antioxidants; Ascorbic Acid; Bilirubin; Catalase; Diabetes Mellitus; Hypoglycemic Agents; Methanol; Nigella sativa; Plant Extracts; Rabbits; Rats; Vitamins

Serotonin (5-HT) levels have been associated with several exclusively metabolic disorders. Herein, a new approach for 5-HT level as a novel biomarker of diabetes mellitus is considered using a simple nanocomposite and HPLC method. Reduced graphene oxide (rGO) comprising gold nanoparticles (AuNPs) was decorated with 18-crown-6 (18.Cr.6) to fabricate a simple nanocomposite (rGO-AuNPs-18.Cr.6). The nanocomposite was positioned on a glassy carbon electrode (GCE) to form an electrochemical sensor for the biomarker 5-HT in the presence of L-tryptophan (L-Trp), dopamine (DA), ascorbic acid (AA), urea, and glucose. The nanocomposite exhibited efficient catalytic activity for 5-HT detection by square-wave voltammetry (SWV). The proposed sensor displayed high selectivity, excellent reproducibility, notable anti-interference ability, and long-term stability even after 2 months. SWV defined a linear range of 5-HT concentration from 0.4 to 10 μg L

Topics: Animals; Ascorbic Acid; Biomarkers; Diabetes Mellitus; Dopamine; Electrochemical Techniques; Electrodes; Glucose; Gold; Hydrogen Bonding; Limit of Detection; Metal Nanoparticles; Microscopy, Electron, Scanning; Microscopy, Electron, Transmission; Nanocomposites; Particle Size; Reproducibility of Results; Serotonin; Tryptophan; Urea; Zebrafish

A family of 12 triazolo-pyridazine-6-yl-substituted piperazines (5a-l) was synthesized and evaluated for their Dipeptidyl peptidase-4 (DPP-4) inhibition potentials in order to develop them as anti-diabetic medications. In the two-step synthesis process, 6-chloro-3-(m-tolyl)-[1,2,4]triazolo[4,3-b]pyridazine was synthesized with one-pot mode using pyridine, 3,6-dichloropyridazine 5-(3-methyl-phenyl)tetrazole in toluene. Conjugating corresponding 2° amines with 6-chloro-3-(m-tolyl)-[1,2,4]triazolo[4,3-b]pyridazine afforded the target triazolo-pyridazine-6-yl-substituted piperazines (5a-l). DPP-4 inhibition potential of these compounds was testified in silico and in nitro along with their insulinotropic activities in 832/13 INS-1 cells. H

Topics: Diabetes Mellitus; Dipeptidyl Peptidase 4; Dipeptidyl-Peptidase IV Inhibitors; Dose-Response Relationship, Drug; Drug Discovery; Humans; Hypoglycemic Agents; Insulin; Molecular Structure; Piperazines; Pyridazines; Structure-Activity Relationship; Triazoles

The advancement of autologous mesenchymal stem cell (MSC) therapy for the treatment of non-healing diabetic wounds is hampered by endogenous MSC dysfunction and limited viability of cells post-transplantation into the pathological wound environment. The development of effective strategies to restore the functional capabilities of these impaired MSCs prior to transplantation may be a key to their ultimate success as wound repair mediators. The current study therefore investigated whether antioxidant preconditioning [7.5 mM N-acetylcysteine (NAC) + 0.6 mM ascorbic 2-phosphate (AAP)] could restore the growth rate, migration ability and viability of impaired MSCs and whether this restored state is maintained in the presence of diabetic wound fluid (DWF). Healthy control (source: wild type, C57BL/6J mice) (n = 12) and impaired/diabetic MSCs (source: obese prediabetic, B6.Cg-Lepob/J mice) (n = 12) were isolated from the bone marrow of mice. Treatment groups post-isolation were as follow: (a) No treatment (baseline phenotype): MSCs expanded in standard growth media (SGM) (±8 days) and only exposed to growth media. (b) DWF (baseline response): MSCs expanded in SGM (±8 days) followed by exposure to DWF (24 hours, 48 hours, 96 hours). (c) Antioxidant preconditioning (preconditioned phenotype): MSCs expanded in the presence of NAC/AAP (±8 days). (d) Antioxidant preconditioning + DWF (preconditioned response): MSCs expanded in the presence of NAC/AAP (±8 days) followed by exposure to DWF (24 hours, 48 hours, 96 hours). The results demonstrated that expansion of MSCs (both healthy control and impaired diabetic) in the presence of combined NAC/AAP treatment improved ex vivo MSC viability and protected MSCs in the presence of DWF. Despite improved viability, AAP/NAC could however not rescue the reduced proliferation and migration capacity of impaired diabetic MSCs. The protective effect of NAC/AAP preconditioning against the toxicity of DWF could however be a potential strategy to improve cell number post-transplantation.

Topics: Acetylcysteine; Animals; Antioxidants; Ascorbic Acid; Case-Control Studies; Cell Movement; Cell Proliferation; Cell Survival; Diabetes Mellitus; Exudates and Transudates; Mesenchymal Stem Cell Transplantation; Mesenchymal Stem Cells; Mice; Mice, Obese; Osteogenesis; Prediabetic State; Transplantation, Autologous; Wounds and Injuries

Diabetes mellitus (DM) is a major health problem with an increasing global prevalence. It is usually associated with an imbalance between pro-oxidant mechanisms and antioxidant defenses, contributing to oxidative-stress, and this leads to an increased susceptibility to endothelial dysfunction, atherosclerosis, insulin-resistance and impaired-pancreatic β-cell function.. We have assessed the Prooxidant-antioxidant balance (PAB) and anti-hemolytic effect of Thuja orientalis L using the PAB assay and the analysis of hematological markers.. The antioxidant and anti-hemolytic activity of Thuja orientalis was evaluated using the PAB assay and the inhibition of RBC hemolysis using the hydrogen peroxide hemolysis test. The percentage of anti-hemolysis was calculated from the ratio of the measurements (A-B)/B×100.. Our results showed that the antioxidant effect of Thuja orientalis L. was greater in water than in ethyl-acetate, ethanol and methanol extract, respectively. We also observed its anti-hemolytic effect, which was higher in water, than in ethyl-acetate, methanol and ethanol extract, respectively. In particular our data showed that the H2O2-induced RBC hemolysis was inhibited in a dose-dependent manner.. we demonstrated the antioxidant and anti-hemolytic effect of Thuja orientalis L. extracts in human serum and RBC, showing its potential property of reducing free radicals supporting further investigations to assess its functional role in larger samples size and in vivo models, as a potential antioxidant agent.

Topics: Antioxidants; Ascorbic Acid; Diabetes Mellitus; Hemolysis; Humans; Oxidants; Plant Extracts; Thuja

The association of dietary vitamin C (vit C) on periodontitis requires more valid evidence from large representative samples to enable sufficient adjustments. This study aimed to evaluate the association between dietary vit C intake and periodontitis after controlling for various confounders in the representative Korean adult population.. A total of 10,930 Korean adults (≥19 years) from the fourth Korean National Health and Nutrition Examination Survey data set were included in this cross-sectional study. Periodontitis was defined as community periodontal index score of 3 or 4. Dietary vit C intake was estimated from a 24-hour dietary record, and categorized into adequate and inadequate according to the Korean Estimated Average Requirement value. Potential confounders included age, sex, income, frequency of tooth brushing, use of floss, dental visit, drinking, smoking, diabetes, hypercholesterolemia, hypertension, and obesity. A multivariable logistic regression analysis and stratified analysis were applied.. Those with inadequate dietary vit C intake were more likely by 1.16 times to have periodontitis than those with adequate dietary vit C intake (adjusted odds ratio [aOR] = 1.16, 95% confidence interval = 1.04-1.29). Lowest and middle-low quartile of dietary vit C intake, compared to highest quartile of dietary vit C intake, showed significant association (aOR = 1.28 and 1.22 respectively), which was in a biological-gradient relationship (trend-p <0.05).. Our data showed that inadequate dietary vit C intake was independently associated with periodontitis among Korean adults. Hence, adequate intake of dietary vitamin C could be substantially important on the promotion of periodontal health among Korean adults.

Topics: Adult; Aged; Alcohol Drinking; Ascorbic Acid; Cross-Sectional Studies; Diabetes Mellitus; Female; Humans; Income; Male; Middle Aged; Nutrition Surveys; Obesity; Odds Ratio; Periodontal Index; Periodontitis; Republic of Korea; Smoking; Toothbrushing; Vitamins; Young Adult

Vegetable and fruit consumption may have a protective effect against several types of cancers. However, the effect on biliary cancers is unclear. We investigated the association of vegetable/fruit consumption with the risks of gallbladder cancer (GBC), intrahepatic bile duct cancer (IHBDC) and extrahepatic bile duct cancer (EHBDC) in a population-based prospective cohort study in Japan. Hazard ratios (HRs) and 95% confidence intervals (CIs) were calculated using the Cox proportional hazard model, and the exposure level was categorized into quartiles, with the lowest group used as the reference. A total of 80,371 people aged 45 to 74 years were enrolled between 1995 and 1999, and followed up for 1,158,632 person-years until 2012, during which 133 GBC, 99 IHBDC, and 161 EHBDC cases were identified. Increased consumption of total vegetable and fruit was significantly associated with a decreased risk of EHBDC (HR = 0.49; 95% CI: 0.29-0.81 for the highest group; p trend = 0.005). From the analysis of relevant nutrients, significantly decreased risk of EHBDC was associated with folate and insoluble fiber (HR = 0.48, 0.53; 95% CI: 0.28-0.85, 0.31-0.88 for the highest group; p trend = 0.010, 0.023; respectively), and a significant trend of decreased EHBDC risk associated with vitamin C was observed (p trend = 0.029). No decreased risk of GBC and IHBDC was found. Our findings suggest that increased vegetable/fruit consumption may decrease a risk of EHBDC, and folate, vitamin C, and insoluble fiber might be key contributors to the observed protective effect.

Topics: Adult; Alcohol Drinking; Ascorbic Acid; Bile Duct Neoplasms; Carcinoma; Cholelithiasis; Comorbidity; Diabetes Mellitus; Diet; Dietary Fiber; Female; Folic Acid; Follow-Up Studies; Fruit; Gallbladder Neoplasms; Hepatitis, Viral, Human; Humans; Japan; Life Style; Male; Middle Aged; Proportional Hazards Models; Prospective Studies; Smoking; Surveys and Questionnaires; Vegetables

Topics: Adult; Ascorbic Acid; Diabetes Mellitus; Dietary Supplements; Fruit; Humans; Prediabetic State; Vegetables; Vitamin D; Vitamins

To assess in a population deprived from regular dental care the relationship between alveolar bone loss (ABL) and environmental/systemic conditions.. The study population consisted of subjects from the Purbasari tea estate on West Java, Indonesia. A full set of dental radiographs was obtained of each subject and amount of ABL was assessed. In addition, the following parameters were evaluated: plasma vitamin C, vitamin D3 , HbA1c and CRP, the haptoglobin phenotype, presence of putative periodontopathic bacteria and viruses, dietary habits, smoking and anthropometrics.. In this population 45% showed vitamin C depletion/deficiency, 82% had vitamin D3 insufficiency/deficiency, 70% were in a pre-diabetic state, 6% had untreated diabetes, 21% had elevated CRP values ranging from 3.1 to 16.1 mg/l. Results of the regression analysis, including all above mentioned parameters, showed four significant predictors, explaining 19.8% of the variance of ABL. Number of Porphyromonas gingivalis cells and CRP values showed a positive relationship with ABL, whereas BMI and number of guava fruit servings were negatively related.. Results confirm previous findings that elevated levels of P. gingivalis may be indicative for periodontitis progression. A new finding is that guava fruit consumption may play a protective role in periodontitis in a malnourished population.

Topics: Adult; Alveolar Bone Loss; Ascorbic Acid; Ascorbic Acid Deficiency; Body Mass Index; C-Reactive Protein; Cholecalciferol; Diabetes Mellitus; Environment; Feeding Behavior; Female; Glycated Hemoglobin; Haptoglobins; Herpesvirus 4, Human; Humans; Indonesia; Male; Middle Aged; Periodontitis; Phenotype; Pilot Projects; Porphyromonas gingivalis; Prediabetic State; Psidium; Smoking; Vitamin D Deficiency; Vitamins

Topics: Ascorbic Acid; Bacteria; Biomass; Cell Cycle; Diabetes Mellitus; Diabetes Mellitus, Type 2; Erythrocytes; Glucose; Humans; Obesity; Polyhydroxyalkanoates; Sewage; Starvation; United Kingdom; Vitamin A; Vitamin A Deficiency

A simple method of using fingerstick blood glucose (FSBG) monitors to estimate blood ascorbate values after high-dose intravenous (IV) ascorbate infusion is evaluated as a substitution for high-performance liquid chromatography (HPLC) measurement.. In 33 participants, readings from FSBG monitors were taken before and after IV ascorbate infusions at various time points, with the postinfusion FSBG readings subtracted from the baseline glucose readings. The results of the subtractions (AAFSBG) were correlated with ascorbate concentrations detected by HPLC (AAHPLC).. A linear regression was found between ascorbate concentrations detected by the fingerstick method (AAFSBG) and by HPLC (AAHPLC). The linear correlations were identical in healthy subjects, diabetic subjects, and cancer patients. Analysis of variance obtained an AAFSBG/AAHPLC ratio of 0.90, with a 90% confidence interval of (0.69, 1.20). The corrections of AAFSBG improved similarity to AAHPLC but did not significantly differ from the uncorrected values.. The FSBG method can be used as an approximate estimation of high blood ascorbate concentration after IV ascorbate (>50 mg/dL, or 2.8 mM) without correction. However, this measurement is not accurate in detecting lower or baseline blood ascorbate. It is also important to highlight that in regard to glucose monitoring, FSBG readings will be erroneously elevated following IV ascorbate use and insulin should not be administered to patients based on these readings.

Topics: Ascorbic Acid; Blood Glucose; Chromatography, High Pressure Liquid; Diabetes Mellitus; Dose-Response Relationship, Drug; Humans; Infusions, Intravenous; Linear Models; Neoplasms; Reproducibility of Results

The prevalence of diabetes is increasing in China. Glucose control is very important in diabetic patients. The aim of this study was to compare the accuracy of five glucose meters used in Chinese hospitals with a reference method, in the absence and presence of various factors that may interfere with the meters.. Within-run precision of the meters was evaluated include Roche Accu-Chek Inform®, Abbott Precision PCx FreeStyle®, Bayer Contour®, J&J LifeScan SureStep Flexx®, and Nova Biomedical StatStrip®. The interference of hematocrit level, maltose, ascorbic acid, acetaminophen, galactose, dopamine, and uric acid were tested in three levels of blood glucose, namely low, medium, and high concentrations. Accuracy (bias) of the meters and analytical interference by various factors were evaluated by comparing results obtained in whole blood specimens with those in plasma samples of the whole blood specimens run on the reference method. Impact of oxygen tension on above five blood glucose meters was detected.. Precision was acceptable and slightly different between meters. There were no significant differences in the measurements between the meters and the reference method. The hematocrit level significantly interfered with all meters, except StatStrip. Measurements were affected to varying degrees by different substances at different glucose levels, e.g. acetaminophen and ascorbic acid (Freestyle), maltose and galactose (FreeStyle, Accu-Chek), uric acid (FreeStyle, Bayer Contour), and dopamine (Bayer Contour).. The measurements with the five meters showed a good correlation with the plasma hexokinase reference method, but most were affected by the hematocrit level. Some meters also showed marked interference by other substances.

Topics: Acetaminophen; Ascorbic Acid; Blood Chemical Analysis; Blood Glucose; China; Diabetes Mellitus; Dimensional Measurement Accuracy; Dopamine; Galactose; Hematocrit; Hexokinase; Hospitals; Humans; Maltose; Oxygen; Reference Values; Uric Acid

Quantification of Total Antioxidant Capacity (TAC) of human plasma is an important clinical target, since many diseases are suspected to be related with oxidative stress. The CUPRAC-BCS (BCS=Bathocuproinedisulfonic acid) method was chosen since it works using the photometric principle, with stable and inexpensive reagents and at physiological pH.. The method is based on the complex equilibria between Cu(II)-BCS (reagent) and Cu(I)-BCS. Cu(I)-BCS complex is formed by reducing ability of the plasma redox active substances. The photometric signal is achieved at 478 nm and calibration is performed using urate as a reference substance.. Linearity, linear working range, sensitivity, precision, LoD, LoQ, selectivity and robustness have been considered to validate the method. Absorbance at 478 nm was found linear from 0.0025 up to 2.0 mmol L(-1) of urate reference solution. Precision was evaluated as within-day repeatability, Sr=4 µmol L(-1), and intermediate-precision, SI(T)=15 µmol L(-1). LoD and LoQ, resulted equal to 7.0 µmol L(-1) and 21 µmol L(-1) respectively while robustness was tested having care for pH variation during PBS buffer preparation. Tests on plasma (80 samples) and on human cerebrospinal fluid (30 samples) were conducted and discussed.. By the analytical point of view, the photometric method was found to be simple, rapid, widely linear and reliable for the routine analysis of a clinical laboratory. By the clinical point of view, the method response is suitable for the study of chemical plasma quantities related to redox reactivity.

Topics: Antioxidants; Ascorbic Acid; Calibration; Cations, Divalent; Cations, Monovalent; Copper; Diabetes Mellitus; Humans; Hydrogen-Ion Concentration; Oxidation-Reduction; Oxidative Stress; Phenanthrolines; Photometry; Reference Standards; Renal Dialysis; Sensitivity and Specificity; Uric Acid

Dental erosion is a multifactorial disease and is associated with dietary habits in infancy and adolescence.. To investigate possible associations among dental erosion and diet, medical history and lifestyle habits in Brazilian schoolchildren.. The sample consisted of a random single centre cluster of 414 adolescents (12- and 16-years old) of both genders from private and public schools in Bauru (Brazil). The O'Brien [Children's Dental Health in the United Kingdom, 1993 (1994) HMSO, London] index was used for dental erosion assessment. Data on medical history, rate and frequency of food and drinks consumption, and lifestyle habits were collected by a self-reported questionnaire. Odds ratios with 95% confidence intervals were used to assess the univariate relationships between variables. Analysis of questionnaire items was performed by multiple logistic regression analysis. The statistical significance level was set at 5%.. The erosion present group comprised 83 subjects and the erosion absent group 331. There were no statistically significant correlations among dental erosion and the consumption of food and drinks, medical history, or lifestyle habits.. The results indicate that there was no correlation between dental erosion and the risk factors analysed among adolescents in Bauru/Brazil and further investigations are necessary to clarify the multifactorial etiology of this condition.

Topics: Adolescent; Ascorbic Acid; Asthma; Beverages; Brazil; Carbonated Beverages; Child; Cross-Sectional Studies; Diabetes Mellitus; Drinking Behavior; Drug Therapy; Feeding Behavior; Female; Food; Gastrointestinal Diseases; Humans; Life Style; Male; Risk Factors; Tooth Erosion; Vitamins; Vomiting

Understanding the relationship between multivitamin use and diabetes risk is important given the wide use of multivitamin supplements among U.S. adults.. We prospectively examined supplemental use of multivitamins and individual vitamins and minerals assessed in 1995-1996 in relation to self-reported diabetes diagnosed after 2000 among 232,007 participants in the National Institutes of Health-American Association of Retired Persons Diet and Health Study. Multivitamin use was assessed by a food-frequency questionnaire at baseline. Odds ratios (ORs) and 95% CIs were calculated by logistic regression models, adjusted for potential confounders. In total, 14,130 cases of diabetes diagnosed after 2000 were included in the analysis.. Frequent use of any multivitamins was not associated with risk of diabetes after adjustment for potential confounders and uses of individual supplements. Compared with nonusers of any multivitamins, the multivariate ORs among users were 1.07 (95% CI 0.94-1.21) for taking vitamins less than once per week, 0.97 (0.88-1.06) for one to three times per week, 0.92 (0.84-1.00) for four to six times per week, and 1.02 (0.98-1.06) for seven or more times per week (P for trend = 0.64). Significantly lower risk of diabetes was associated with the use of vitamin C or calcium supplements. The multivariate ORs comparing daily users with nonusers were 0.91 (0.86-0.97) for vitamin C supplements and 0.85 (0.80-0.90) for calcium supplements. Use of vitamin E or other individual vitamin and mineral supplements were not associated with diabetes risk.. In this large cohort of U.S. older adults, multivitamin use was not associated with diabetes risk. The findings of lower diabetes risk among frequent users of vitamin C or calcium supplements warrant further evaluations.

Topics: Aged; Ascorbic Acid; Diabetes Mellitus; Dietary Supplements; Female; Humans; Male; Middle Aged; Minerals; Prospective Studies; Risk Factors; United States; Vitamins

The scope of the diabetes epidemic stresses the critical need for primary prevention. The consumption of foods high in vitamin C has been associated with lower risk of diabetes. The aim of this study was to analyze the relation between vitamin C concentration and glycemic control index in a large sample of U.S. adults without a history of diabetes.. We analyzed data collected from 7697 adult participants in the National Health and Nutrition Examination Survey (NHANES) 2003-2006 who did not report a history of diabetes. Multivariate linear regression analyzed the association of vitamin C and hemoglobin A1c (A1c) levels after accounting for potential confounders. We also conducted stratified analyses based on race/ethnicity, gender, age group, body mass index, and vitamin D status.. Vitamin C concentrations were inversely associated with A1c (p = 0.0202). Stronger inverse associations were observed in subjects 18-44 years of age (p = 0.0017), as well as in female (p = 0.0035) and Mexican American (p = 0.0149) subgroups. Evidence of a significant interaction between vitamin C and vitamin D was noted in subjects aged 18-44 years and in females (p = 0.0073 and 0.0095 respectively), with the inverse association tending to be evident at lower levels of vitamin D.. Vitamin C status may influence glycemic control. Investigators should be cognizant of the interaction of vitamins C and D and should take this into consideration in planning future studies.

Topics: Adolescent; Adult; Aged; Ascorbic Acid; Blood Glucose; Body Mass Index; Cross-Sectional Studies; Diabetes Mellitus; Female; Glycated Hemoglobin; Humans; Linear Models; Male; Mexican Americans; Middle Aged; Multivariate Analysis; Nutrition Surveys; Vitamin D; Young Adult

The haptoglobin (Hp) 2-2 genotype is associated with increased risk of cardiovascular disease (CVD) in diabetes (DM). We recently proposed this increased risk arises from the tethering of redox active hemoglobin (Hb) to high density lipoprotein (HDL), thereby resulting in oxidative modification of HDL. Clinical trials have demonstrated that vitamin E (alpha-tocopherol) decreases while vitamin C increases CVD in Hp 2-2 DM individuals. We sought to test the hypothesis that the interaction of alpha-tocopherol or vitamin C on CVD in Hp 2-2 DM was due to their divergent effects on HDL oxidation and function. Vitamin C significantly increased while alpha-tocopherol completely blocked oxidation mediated by glycosylated Hb-Hp 2-2. Vitamin C had no benefit while alpha-tocopherol completely restored HDL function in Hp 2-2 DM mice. Co-administration of vitamin C mitigated the protective effects of alpha-tocopherol on HDL. There exists a pharmacogenomic interaction between vitamin C and alpha-tocopherol and the Hp 2-2 genotype on HDL function and structure. Choosing the correct antioxidant in the correct subset of patients may be critical in order to demonstrate benefit from antioxidant therapy.

Topics: alpha-Tocopherol; Animals; Antioxidants; Ascorbic Acid; Biological Transport; Cell Line; Cholesterol; Diabetes Mellitus; Genotype; Haptoglobins; Hemoglobins; Humans; Iron Chelating Agents; Lipid Peroxidation; Lipoproteins, HDL; Mice; Mice, Transgenic; Oxidation-Reduction; Protein Binding; Rhodamines

To clarify the association of tooth loss with dietary intakes among dentists, for whom sufficient dental care is available.. We analyzed the data from 20 366 Japanese dentists (mean age +/- SD, 52.2 +/- 12.1 years; women 8.0%) who participated in a nationwide cohort study from 2001 to 2006. The baseline questionnaire included a validated food-frequency questionnaire to estimate intakes of foods and nutrients. We computed the geometric means of daily intakes by the number of teeth, adjusting for age, sex, smoking, physical activity, and history of diabetes.. The mean intakes of some key nutrients and food groups, such as carotene, vitamins A and C, milk and dairy products, and vegetables including green-yellow vegetables, decreased with the increasing number of teeth lost (P for trend <0.05). On the contrary, mean intakes of carbohydrate, rice, and confectioneries were increased among those with fewer teeth (P for trend <0.05). The difference in the geometric mean (%) between totally edentulous subjects and those with > or =25 teeth, that is [(Geometric mean for > or =25 teeth) - (Geometric mean for 0 teeth)]/(Geometric mean for > or =25 teeth) x 100, was 14.3%, 8.6%, 6.1%, and -6.1% for carotene, vitamin C, vitamin A, and carbohydrate, respectively. For food groups, it was 26.3%, 11.9%, 5.6%, -9.5%, and -29.6% for milk and dairy products, green-yellow vegetables, total vegetables, rice, and confectioneries, respectively.. Tooth loss was linked with poorer nutrition even among dentists.

Topics: Adult; Age Factors; Aged; Aged, 80 and over; Ascorbic Acid; Candy; Carotenoids; Cohort Studies; Dairy Products; Dentists; Diabetes Mellitus; Diet; Dietary Carbohydrates; Feeding Behavior; Female; Humans; Japan; Jaw, Edentulous, Partially; Male; Middle Aged; Motor Activity; Mouth, Edentulous; Nutritional Status; Oryza; Sex Factors; Smoking; Tooth Loss; Vegetables; Vitamin A

Leaves of Cecropia pachystachya are described in the folk medicine as possessing antitusive, expectorant, antiasthmatic and hypoglycemic effects.. To investigate the hypoglycemic and antioxidant effects of methanolic extract from the leaves of Cecropia pachystachya. The total amount of phenolic and flavonoids compounds was determined and the qualitative composition of the extract was analyzed.. The hypoglycemic effect of the extract was tested in normal, glucose loading and alloxan-induced diabetic rats. The antioxidant activity was assessed by DPPH free radical scavenging and reduction power assays. The total amount of phenolic and flavonoids compounds was determined by Folin-Denis and AlCl(3) reagent method, respectively. The qualitative composition of the extract was analyzed using a HPLC-DAD system.. The glucose tolerance test showed that in diabetic rats, the extract caused a significant hypoglycemic effect with a blood glucose reduction of 68% after 12h. The administration of the extract in alloxan-induced diabetic rats also produced a significant reduction in the blood glucose levels at all points being more pronounced at 90min (reduction of 60%). After 120min, no significant difference was observed between the blood levels of the rats treated with the extract and those treated with the standard drugs (metformin and glibenclamide). The extract also presented relevant antioxidant activity with IC50=3.1microg/ml (DPPH assay) and EC50=10.8microg/ml (reduction power). Results were compared with the reference antioxidants quercetin, rutin, and ascorbic acid. The content of flavonoids was 83mg/g plant and that of phenolics was 326mg/g plant. Chlorogenic acid and the C-glycosylated flavones, orientin and isoorientin, were identified in the extract.. In conclusion, the findings showed that the folk medicinal plant Cecropia pachystachya possesses hypoglycemic and antioxidant effects which confirmed the traditional use of the plant in the treatment of diabetes. Chlorogenic acid and the C-glycosylated flavonoids may explain these activities.

Topics: Alloxan; Animals; Antioxidants; Ascorbic Acid; Blood Glucose; Cecropia Plant; Diabetes Mellitus; Diabetes Mellitus, Type 2; Flavonoids; Free Radical Scavengers; Glucose Tolerance Test; Glucosides; Glyburide; Hypoglycemic Agents; Male; Medicine, Traditional; Metformin; Phenols; Plant Extracts; Rats; Rats, Wistar

Hepatitis C virus (HCV) is the most common indication for liver transplantation, but HCV recurrence is frequent after 1 year and is associated with increased morbidity and mortality. Oxidative stress (OxS) is involved in the pathogenesis of HCV, but little is known about its presence prior to disease recurrence.. To determine if at 6 months HCV-positive liver recipients (HCV-OLT) without recurrence were oxidatively stressed.. 33 HCV-OLTs, 12 controls, and 39 HCV-positive nontransplant patients (HCV-NTs). OxS was assessed by using commercial kits to measure liver lipid peroxidation (LPO) and antioxidant potential (AOP). Plasma vitamin E, retinol (HPLC), and vitamin C (spectrophotometry) were assessed. We collected Anthropometry and 3-day food records. We performed analysis by the Kruskal-Wallis test expressing data as mean values +/- standard errors of the mean.. Waist-hip ratio was higher in both HCV-OLTs and HCV-NTs compared to the controls. HCV-OLTs showed higher hepatic LPO (mumol malondialdehyde/g tissue) versus controls (1.4 +/- 0.20 vs 0.54 +/- 0.10; P = .010) and compared to HCV-NTs (0.98 +/- 0.17; P = .030). No significant differences were found among the groups regarding hepatic AOP. However, lower plasma AOP (micromols UEA) were observed in HCV-OLTs (0.07 +/- 0.008) versus controls (0.17 +/- .040; P = .021) or HCV-NTs (0.08 +/- 0.009; P = .015) versus controls. Plasma gamma-tocopherol was higher in HCV-OLTs and HCV-NTs compared to controls (P = .001). We observed lower vitamin A intake in HCV-OLTs compared with the other two groups (P = .001).. HCV-OLTs without disease recurrence are oxidatively stressed compared with control and HCV-NTs. Future research is needed to determine the impact of this increased oxidative stress on HCV disease recurrence.

Topics: Antioxidants; Ascorbic Acid; Body Height; Body Mass Index; Body Weight; Diabetes Complications; Diabetes Mellitus; Female; Hepatitis C; Humans; Lipid Peroxides; Liver Transplantation; Male; Middle Aged; Oxidative Stress; Recurrence; Vitamin A; Vitamin E; Waist-Hip Ratio

This study was performed to investigate the relationship between serum L-ascorbic acid, vitamin C intake, and diabetes in a nested case-control study. A cross-sectional survey of diet and health was conducted in 2,048 adults with an age of 30 y or older in Yonchon County, Korea. An oral glucose tolerance test was administered to all participants. One hundred cases of newly diagnosed diabetes were identified. Two healthy controls for each case matched with age, gender, drinking status, and smoking status were selected among the survey participants. L-Ascorbic acid levels were analyzed in fasting serum samples and one 24-h dietary recall was performed. Dietary vitamin C intake of persons with diabetes was 50.1±47.6 mg/d and that of controls was 55.1±41.1 mg/d. People with diabetes (22.3±16.8 µmol/L) have lower serum ascorbic acid levels than their controls (26.3±17.0 µmol/L) and the difference was significant by paired t-test (p<0.01). The association between diabetes and serum ascorbic acid level was still significant in non-smokers (24.2±17.8 µmol/L for the diabetes group and 29.5±16.7 µmol/L for the control group, p<0.01) but not in smokers (19.4±15.7 µmol/L for the diabetes group and 21.2±16.0 µmol/L for the control group). Our results suggest that diabetes and smoking interactively affect serum ascorbic acid levels. Since this population had poor nutritional status of vitamin C, further investigation of association between serum ascorbic acid level and diabetes and smoking by the level of vitamin C consumption is warranted.

Topics: Adult; Aged; Ascorbic Acid; Case-Control Studies; Diabetes Mellitus; Female; Glucose Tolerance Test; Humans; Male; Middle Aged; Republic of Korea; Smoking

There is significant evidence that reactive oxygen species play an important role in endothelial dysfunction, ischemia/reperfusion injury as well as in the pathogenesis of diabetes mellitus (DM). It is also known that vitamins C and E have substantial antioxidant properties. However, clinical evidence concerning this topic is insufficient so far. The aim of the present study was to determine if the administration of vitamins C and E influences the outcome in diabetic patients with acute myocardial infarction (AMI).. Among 800 patients with AMI included in the MIVIT (Myocardial Infarction and Vitamins) study, 122 patients (15%) had confirmed DM. A retrospective analysis of the influence of vitamins C and E on 30-day cardiac mortality in patients with or without DM was performed.. There was a significant reduction in 30-day cardiac mortality in diabetic patients treated with antioxidant vitamins C and E [5 (8%) vs. 14 (22%); OR 0.32, 95% CI 0.11-0.93; p = 0.036]. Such an effect has not been observed in patients without DM [19 (6%) vs. 19 (6%); OR 0.97, 95% CI 0.51-1.85; p = 0.94].. The results suggest that early administration of antioxidant vitamins C and E in patients with AMI and concomitant DM reduces cardiac mortality.

Topics: Aged; Antioxidants; Ascorbic Acid; Diabetes Mellitus; Female; Humans; Male; Middle Aged; Myocardial Infarction; Oxidative Stress; Pilot Projects; Randomized Controlled Trials as Topic; Reactive Oxygen Species; Retrospective Studies; Risk Factors; Treatment Outcome; Vitamin E

Topics: Ascorbic Acid; Biomarkers; Body Weight; Diabetes Mellitus; Diet; Exercise; Humans; Satiety Response

Hitherto unknown efficacy of the peel extracts of Mangifera indica (MI), Cucumis melo (CM) and Citrullus vulgaris (CV) fruits in ameliorating the diet-induced alterations in dyslipidemia, thyroid dysfunction and diabetes mellitus have been investigated in rats. In one study, out of 4 different doses (50-300 mg/kg), 200 mg/kg of MI and 100 mg/kg for other two peel extracts could inhibit lipidperoxidation (LPO) maximally in liver. In the second experiment rats were maintained on pre-standardized atherogenic diet CCT (supplemented with 4% cholesterol, 1% cholic acid and 0.5% 2-thiouracil) to induce dyslipidemia, hypothyroidism and diabetes mellitus and the effects of the test peel extracts (200 mg/kg of MI and 100 mg/kg for CM and CV for 10 consecutive days) were studied by examining the changes in tissue LPO (in heart, liver and kidney), concentrations of serum lipids, thyroid hormones, insulin and glucose. Rats, treated simultaneously with either of the peel extracts reversed the CCT-diet induced increase in the levels of tissue LPO, serum lipids, glucose, creatinine kinase-MB and decrease in the levels of thyroid hormones and insulin indicating their potential to ameliorate the diet induced alterations in serum lipids, thyroid dysfunctions and hyperglycemia/diabetes mellitus. A phytochemical analysis indicated the presence of a high amount of polyphenols and ascorbic acid in the test peel extracts suggesting that the beneficial effects could be the result of the rich content of polyphenols and ascorbic acid in the studied peels.

Topics: Animals; Ascorbic Acid; Atherosclerosis; Blood Glucose; Citrullus; Creatine Kinase, MB Form; Cucumis melo; Diabetes Mellitus; Diet, Atherogenic; Dyslipidemias; Flavonoids; Fruit; Hyperglycemia; Hypoglycemic Agents; Hypothyroidism; Lipid Peroxidation; Lipids; Mangifera; Phenols; Phytotherapy; Plant Extracts; Polyphenols; Rats; Rats, Wistar; Thyroxine; Triiodothyronine

Eleven antidiabetic traditional Chinese medicine (TCM) extracts rich in saponins were examined for their antioxidant and antiglycation activities. The antioxidant activities of these extracts were evaluated by studying the inhibition of lipid peroxidation in rat liver microsomes induced by ascorbate/Fe2+, cumine hydroperoxide (CHP) or CCl4/reduced form of nicotinamide-adenine dinucleotide phosphate (NADPH). The antioxidant capacities were also evaluated by studying the scavenging of 2,2'-diphenyl-1-picrylhydrazyl (DPPH) free radical. The antiglycation activities of these extracts were evaluated by hemoglobin-delta-gluconolactone (delta-Glu) assay, bovine serum albumin (BSA)-glucose assay and N-acetyl-glycyl-lysine methyl ester (GK peptide)-ribose assay. Aralia taibaiensis outperformed other extracts in most of the assays except inhibition of early glycation products formation, where Acanthopanax senticosus showed higher activity. Aralia taibaiensis was particularly potent in inhibiting the late glycation and formation of advanced glycation end products (AGEs) on proteins. The antioxidant and antiglycation activities of most extracts were correlated with the saponin content. The results demonstrate that the antidiabetic activities of most extracts could be explained, at least in part, by their combined antioxidant and antiglycation properties.

Topics: Animals; Antioxidants; Ascorbic Acid; Biphenyl Compounds; Diabetes Mellitus; Drugs, Chinese Herbal; Free Radical Scavengers; Hydrazines; Lipid Peroxidation; Microsomes, Liver; Nitrosamines; Oxidation-Reduction; Picrates; Rats; Rats, Sprague-Dawley; Saponins

Oxidative stress is defined as an imbalance between the production of reactive oxygen species (ROS) and the antioxidant network, in favour of the former. Our lifestyle (smoking, alcoholism, obesity, intense physical exercise), but also our inadequate diet, contributes to significantly increase the production of ROS in our organism. This is potentially associated with an increased risk of developing ageing-related pathologies such as cardiovascular diseases and cancer. As a matter of prevention, it is necessary to have in hands a high technology allowing to correctly evidence the oxidative stress status of an individual in order to render optimal our antioxidant defences and to decrease the oxidative damages in DNA, proteins and lipids.

Topics: Amino Acids; Antioxidants; Ascorbic Acid; Biomarkers; Carotenoids; Coenzymes; Diabetes Mellitus; DNA Damage; Electron Transport Chain Complex Proteins; Free Radicals; Glutathione Peroxidase; Glycation End Products, Advanced; Humans; Lipoproteins; Membrane Lipids; Oxidative Stress; Reactive Oxygen Species; Superoxide Dismutase; Superoxides; Thioredoxins; Trace Elements; Ubiquinone; Vitamin E; Vitamins

We investigated the role of dietary n-3 polyunsaturated fatty acids (n-3 PUFA) in the modulation of total antioxidant status in streptozotocin (STZ)-induced diabetic rats and their macrosomic offspring.. Female wistar rats, fed on control diet or n-3 PUFA diet, were rendered diabetic by administration of five mild doses of STZ on day 5 and were killed on days 12 and 21 of gestation. The macrosomic (MAC) pups were killed at the age of 60 and 90 days.. Lipid peroxidation was measured as the concentrations of plasma thiobarbituric acid reactive substances (TBARS), and the total antioxidant status was determined by measuring (i) plasma oxygen radical absorbance capacity (ORAC), (ii) plasma vitamin A, E and C concentrations, and (iii) antioxidant enzymes activities in erythrocytes. The plasma lipid concentrations and fatty acid composition were also determined.. Diabetes increased plasma triglyceride and cholesterol concentrations, whereas macrosomia was associated with enhanced plasma cholesterol and triglyceride levels, which diminished by feeding n-3 PUFA diet. N-3 PUFA diet also reduced increased plasma TBARS and corrected the decreased ORAC values in diabetic rats and their macrosomic offspring. EPAX diet increased the diminished vitamin A levels in diabetic mothers and vitamin C concentrations in macrosomic pups. Also, this diet improved the decreased erythrocyte superoxide dismutase and glutathione peroxidase activities in diabetic and macrosomic animals.. Diabetes and macrosomia were associated with altered lipid metabolism, antioxidant enzyme activities and vitamin concentrations. N-3 PUFA diet improved hyperlipidemia and restored antioxidant status in diabetic dams and MAC offspring.

Topics: Animals; Animals, Newborn; Antioxidants; Ascorbic Acid; Biomarkers; Diabetes Mellitus; Diabetes Mellitus, Experimental; Diabetes Mellitus, Type 2; Erythrocytes; Fatty Acids; Fatty Acids, Omega-3; Female; Fetal Macrosomia; Free Radical Scavengers; Glutathione Peroxidase; Lipid Peroxidation; Lipids; Pregnancy; Pregnancy in Diabetics; Rats; Rats, Wistar; Superoxide Dismutase; Thiobarbituric Acid Reactive Substances; Vitamin A; Vitamin E

Endothelial dysfunction and underperfusion of exercising muscle contribute to exercise intolerance, hyperventilation, and breathlessness in atrial fibrillation (AF). Cardioversion (CV) improves endothelial function and exercise performance. We examined whether CV is equally beneficial in diabetes and hypertension, diseases that cause endothelial dysfunction and are often associated with AF. Cardiopulmonary exercise and pulmonary and endothelial (brachial artery flow-mediated dilation) function were tested before and after CV in patients with AF alone (n = 18, group 1) or AF with hypertension (n = 19, group 2) or diabetes (n = 19, group 3). Compared with group 1, peak exercise workload, O2 consumption (Vo2), O2 pulse, aerobic efficiency (Delta Vo2/Delta WR), and ratio of brachial diameter changes to flow changes (Delta D/Delta F) were reduced in group 2 and, to a greater extent, in group 3; exercise ventilation efficiency (Ve/Vco2 slope) and dead space-to-tidal volume ratio (Vd/Vt) were similar among groups. CV had less effect on peak workload (+7% vs. +18%), peak Vo2 (+12% vs. +17%), O2 pulse (+33% vs. +50%), Delta Vo2/Delta WR (+7% vs. +12%), Ve/Vco2 slope (-6% vs. -12%), Delta D/Delta F (+7% vs. +10%), and breathlessness (Borg scale) in group 2 than in group 1 and was ineffective in group 3. The antioxidant vitamin C, tested in eight additional patients in each cohort, improved flow-mediated dilation in groups 1 and 2 before, but not after, CV and was ineffective in group 3, suggesting that the oxidative injury is least in lone AF, greater in hypertension with AF, and greater still in diabetes with AF. Comorbidities that impair endothelial activity worsen endothelial dysfunction and exercise intolerance in AF. The advantages of CV appear to be inversely related to the extent of the underlying oxidative injury.

Topics: Aged; Antioxidants; Ascorbic Acid; Atrial Fibrillation; Brachial Artery; Diabetes Complications; Diabetes Mellitus; Diabetes Mellitus, Type 2; Echocardiography; Electric Countershock; Endothelium, Vascular; Exercise Test; Female; Humans; Hypertension; Male; Middle Aged; Myocytes, Cardiac; Reactive Oxygen Species; Regional Blood Flow

The recent increase in both forms of diabetes must be caused by a modern change in the environment. Candidate agents must satisfy at least three criteria. Firstly, the agent must have increased in the environment recently, secondly that it causes diabetes in appropriate animal models, and thirdly that there is a plausible diabetogenic mechanism. Modern food processing can produce glycation end products, oxidised ascorbic acid and lipoic acid, all of which may cause diabetes. Infant formula in particular has high levels of glycation products, and added ascorbic acid. A casomorphin released from A1 beta-casein (but not the A2 variant) can become glycated and have adverse immune effects. Food processing and additives can be posited as a man made cause of the increase in both forms of diabetes. This hypothesis does not exclude other environmental agents which meet the above three criteria.

Topics: Antioxidants; Ascorbic Acid; Diabetes Mellitus; Environment; Food Handling; Glycation End Products, Advanced; Glycosylation; Humans; Oxidation-Reduction; Thioctic Acid

Patients with chronic pancreatitis (CP) are at high risk of antioxidant deficiencies. Furthermore, this disease can lead to diabetes mellitus (DM) that could exacerbate the severity of oxidative stress. Oxidative stress and the resulting LDL oxidation are a major cause of atherosclerosis.. The objective of the study was to ascertain whether diabetes significantly modifies oxidative status in patients with CP.. CP patients with or without DM were compared with type 1 DM patients and healthy control subjects.. Two-way factorial analyses showed that a decrease in the plasma concentrations of vitamin A, vitamin E, and carotenoids accompanied both CP and DM, and CP was also associated with lower plasma concentrations of selenium and zinc, lower catalase activity, and higher plasma concentrations of copper. The lag phase of LDL oxidation was lower in CP patients with or without DM than in the control subjects, whereas there was no significant difference between type 1 DM patients and control subjects. Multivariate analysis showed that LDL vitamin E (R2 = 0.24, P < 0.0001) and fasting plasma glucose (R2 = 0.32, P < 0.0001) concentrations were the main determinants of the lag phase of LDL oxidation.. Antioxidant status is altered in CP patients, particularly in those who also have DM. In these patients, a vitamin E deficiency and an elevated plasma glucose concentration were associated with significantly higher LDL oxidizability.

Topics: Adult; Antioxidants; Ascorbic Acid; Blood Glucose; Body Mass Index; Case-Control Studies; Chronic Disease; Diabetes Mellitus; Humans; Male; Middle Aged; Oxidative Stress; Pancreatitis; Selenium; Vitamin A; Vitamin E; Zinc

Traditional risk factors do not appear to explain fully the variation in the incidence of the cardiovascular diseases (CVD). Epidemiological studies have not been entirely consistent with regard to the relationship between antioxidant vitamin intake and CVD and there appears to be little data on this relationship in non-Caucasian populations. This study aimed to investigate the dietary intake of vitamin A, C, and vitamin E, and carotenoids, serum concentrations of vitamin E and A and indices of lipid peroxidation were measured in male Saudi patients with established CVD and age-matched controls. We assessed the dietary intakes of vitamins A, C, and E and carotenoids, by a food frequency questionnaire. Serum vitamins A and E concentrations were measured by HPLC, in 130 Saudi male subjects with established CVD, and 130 age-matched controls. We also determined serum lipid profiles (total cholesterol, triglycerides, HDL-C, LDL-C), lipoprotein (a), oxidized LDL, and serum lipid peroxide concentrations. Diabetes mellitus (P<0.0001), a positive smoking habit (P<0.0001) and hypertension (P<0.05) were more prevalent among CVD patients. Levels of dietary vitamin E and A were also significantly higher among cases. In conditional logistic regression analysis, the most significant characteristics differentiating CVD patients from controls were diabetes mellitus (Odds ratio 2.49, CI 1.42-4.37, P<0.001), total fat intake (Odds ratio 1.02, CI 1.01-1.03, P<0.01), serum vitamin A (Odds ratio 0.72, CI 0.53-0.99, P<0.05), and the vitamin A/total fat intake ratio (Odds ratio 1.04, CI 1.01-1.06, P<0.01). In a Saudi population, smoking habit and hypertension were significantly more common among patients with CVD. Multivariate analysis showed that dietary total fat and vitamin A and the presence of diabetes mellitus were independent coronary risk factors. This is the first report of a potentially deleterious effect of dietary vitamin A in a non-Caucasian population. However it is possible that unidentified residual confounding factors may account for this finding.

Topics: Antioxidants; Ascorbic Acid; Body Mass Index; Cardiovascular Diseases; Carotenoids; Case-Control Studies; Cholesterol; Chromatography, High Pressure Liquid; Diabetes Mellitus; Dietary Fats; Humans; Hypertension; Lipid Peroxidation; Logistic Models; Male; Middle Aged; Multivariate Analysis; Prevalence; Risk Factors; Saudi Arabia; Smoking; Surveys and Questionnaires; Vitamin A; Vitamin E

Besides the classical cardiovascular diseases, high levels of blood glucose directly interfere with cardiomyocytes. The mechanisms responsible for this have not yet been explored in detail. This study aims to determine if hyperglycaemia has any impact on prominent signalling molecules and on the contractile function of cardiomyocytes. Freshly isolated cardiomyocytes from adult rats were treated with various concentrations of glucose. Formed free radicals were measured by DCF-fluorescence. TGFbeta expression and p38 MAP-kinase (MAPK) activation were measured by Western blotting. The contractile efficiency was determined by measurement of the maximal amount of cell shortening. Glucose (30 mM) caused an increase in formation of radicals, phosphorylation of p38 MAPK, and TGFbeta expression. Under conditions of low viscosity (1 cp), contractile responses to hyperglycaemia (15 mM) were not altered in contrast to control. However, enhancement of viscosity (400 cp) effected a limitation of contractile function. The responsiveness to beta-adrenoceptor stimulation did not change. Neither inhibition of p38 MAPK with SB 202190 (1 microM) nor inhibition of reactive oxygen species with vitamin C did alter these measured functional parameters. Diabetes mellitus directly influences the activation degree of prominent signalling molecules and the contractile function of adult ventricular cardiomyocytes, which results in facilitating in the development of diabetic cardiomyopathy.

Topics: Animals; Antioxidants; Ascorbic Acid; Cells, Cultured; Diabetes Mellitus; Electrophysiology; Glucose; Hyperglycemia; Imidazoles; Isoproterenol; Male; Muscle Contraction; Myocytes, Cardiac; p38 Mitogen-Activated Protein Kinases; Phosphorylation; Protein Kinase Inhibitors; Pyridines; Rats; Rats, Wistar; Reactive Oxygen Species; Receptors, Adrenergic, beta; Signal Transduction; Transforming Growth Factor beta

Studies on plasma nitrotyrosine (NT) levels, a measure of oxidative injury, in diabetes are limited and discordant; the amount of antioxidants might represent a possible explanation for the discordant results. The aim of this paper is to evaluate the association between plasma NT levels and glucose tolerance status, according to antioxidant vitamin intakes.. In three hundred men randomly selected from a population-based cohort, NT levels were measured and dietary intake assessed by a food-frequency questionnaire. Results NT values were similar in patients with diabetes (n = 34), impaired fasting glucose (n = 77) and normoglycaemic subjects (n = 189). However, in subjects with lower than recommended daily intakes of antioxidant vitamins C and A, NT levels were significantly higher in the diabetic patients. In a multiple regression model, after adjustments for age, body mass index (BMI) and smoking habits, NT levels were significantly associated with fasting glucose in patients with lower intakes of vitamin C (beta = 11.4; 95% CI 1.3-21.5) and vitamin A (beta = 14.9; 95% CI 3.9-25.9), but not in subjects with lower intake of vitamin E.. A significant positive correlation between NT levels and fasting glucose is evident only in the presence of a reduced intake of some antioxidant vitamins. These findings might explain, at least in part, the discrepant results of previous studies and, if confirmed by further studies, suggest a simple measure (a balanced diet) to alleviate the increased oxidative stress of diabetes.

Topics: Age Factors; Antioxidants; Ascorbic Acid; Blood Glucose; Body Mass Index; Cohort Studies; Diabetes Mellitus; Diet; Humans; Hyperglycemia; Male; Middle Aged; Smoking; Tyrosine; Vitamin A; Vitamin E; Vitamins

Topics: Ascorbic Acid; Cooking; Diabetes Mellitus; Energy Intake; Humans; Immune System; Menu Planning

Topics: Antioxidants; Arthritis, Rheumatoid; Ascorbic Acid; Cardiovascular Diseases; Chronic Disease; Comorbidity; Diabetes Mellitus; Free Radicals; Gastritis; Inflammation; Oxidation-Reduction; Oxidative Stress; Pancreatitis

To compare plasma concentration of alpha-tocopherol and ascorbic acid in healthy seniors (age over 65 years), senior patients with either diabetes mellitus, acute myocardial infarction or dyslipidemia and recommended values of these vitamins.. Studied groups included 30 patients with diabetes mellitus (DM); 30 patients 1 - 2 weeks after acute myocardial infarction (AMI); 11 patients with lipid metabolism disorder (LD, total cholesterol > 6.2 mM); and control group of 27 healthy persons.. Concentration of alpha-tocopherol in DM group was 14.6 +/- 5.3 microM, in AMI group 13.7 +/- 5.6 microM, in LD group 15.9 +/- 5.6 microM and in control group 12.9 +/- 4.1 microM. No statistically significant differences were found. However, comparison of determined values with levels recommended for prevention revealed remarkable low plasma concentration of alpha-tocopherol in the Czech population. Plasma concentration of ascorbic acid in DM group was 47.07 +/- 22.80 microM, in AMI group 33.15 +/- 12.81 microM, in LD group 45.59 +/- 23.02 microM and in control group 43.28 +/- 26.57 microM. No statistically significant differences were found between the controls and individual groups of patients. Plasma concentrations of vitamin C reached the recommended value in all cases except the AMI group, where it was significantly lower.. Seniors in the Czech population were proved to be significantly short of alpha-tocopherol, minor shortage of vitamin C was found only in group of patients with myocardial infarction.

Topics: Aged; alpha-Tocopherol; Antioxidants; Ascorbic Acid; Chromatography, High Pressure Liquid; Diabetes Mellitus; Female; Humans; Hyperlipidemias; Male; Myocardial Infarction

Vitamin C acts as a potent antioxidant; however, it can also be a prooxidant and glycate protein under certain circumstances in vitro. These observations led us to hypothesize that a high intake of vitamin C in diabetic persons might promote atherosclerosis.. The objective was to examine the relation between vitamin C intake and mortality from cardiovascular disease.. We studied the relation between vitamin C intake and mortality from total cardiovascular disease (n = 281), coronary artery disease (n = 175), and stroke (n = 57) in 1923 postmenopausal women who reported being diabetic at baseline. Diet was assessed with a food-frequency questionnaire at baseline, and subjects initially free of coronary artery disease were prospectively followed for 15 y.. After adjustment for cardiovascular disease risk factors, type of diabetes medication used, duration of diabetes, and intakes of folate, vitamin E, and beta-carotene, the adjusted relative risks of total cardiovascular disease mortality were 1.0, 0.97, 1.11, 1.47, and 1.84 (P for trend < 0.01) across quintiles of total vitamin C intake from food and supplements. Adjusted relative risks of coronary artery disease were 1.0, 0.81, 0.99, 1.26, and 1.91 (P for trend = 0.01) and of stroke were 1.0, 0.52, 1.23, 2.22, and 2.57 (P for trend < 0.01). When dietary and supplemental vitamin C were analyzed separately, only supplemental vitamin C showed a positive association with mortality endpoints. Vitamin C intake was unrelated to mortality from cardiovascular disease in the nondiabetic subjects at baseline.. A high vitamin C intake from supplements is associated with an increased risk of cardiovascular disease mortality in postmenopausal women with diabetes.

Topics: Aged; Antioxidants; Ascorbic Acid; Cardiovascular Diseases; Diabetes Mellitus; Diet Surveys; Female; Humans; Iowa; Middle Aged; Postmenopause; Prospective Studies; Registries; Surveys and Questionnaires

We recently reported that PL-AG, a Schiff base of pyridoxal and aminoguanidine, was more effective than aminoguanidine (AG), a well-known anti-diabetic-complication compound, in preventing nephropathy in diabetic mice and presented brief data indicating the antioxidant activity of the adduct. In the present study, we additionally investigated the inhibitory activity of PL-AG in comparison with that of AG against in vitro and in vivo oxidation. PL-AG was more potent than AG and reference compounds such as pyridoxal and pyridoxamine in any of the five antioxidant activities examined in vitro, i.e., hydrogen peroxide-scavenging, hydroxyl radical-scavenging, superoxide radical-scavenging, ascorbic acid-autoxidation inhibitory, and low-density lipoprotein (LDL)-oxidation inhibitory activities, the last two of which were assessed in the presence of Cu(2+). Unlike AG, PL-AG did not show the pro-oxidant activity. The inhibitory activity of PL-AG against lipid peroxidation in diabetic rats was higher than that of AG, for example, the amounts of malondialdehyde in erythrocytes (nmol/g hemoglobin; mean +/- SD) in normal, untreated diabetic, AG-treated diabetic, and PL-AG-treated diabetic rats were 3.53 +/- 0.35, 4.99 +/- 0.23, 4.65 +/- 0.45, and 4.06 +/- 0.35, respectively. A fluorescent substance different from PL-AG was found in the plasma and urine of rats treated with PL-AG. The chemical structure of this substance, i.e., oxidized PL-AG, was determined by a combination of nuclear magnetic resonance, mass, and infrared spectrometry. AG dramatically decreased the pyridoxal phosphate level in the diabetic rat liver, whereas PL-AG only moderately affected it. Our results indicate that the antioxidant activity of PL-AG is due to its chelation with transition metal ions and to scavenging of reactive oxygen species. They also suggest that PL-AG is more promising for the treatment of diabetic complications than AG.

Topics: Animals; Antioxidants; Ascorbic Acid; Aspartate Aminotransferases; Benzoates; Blood Glucose; Body Weight; Chromatography, High Pressure Liquid; Cytochrome P-450 Enzyme System; Diabetes Mellitus; Diabetes Mellitus, Experimental; Dose-Response Relationship, Drug; Erythrocytes; Fluorescent Dyes; Guanidines; Hydrogen Peroxide; Ions; Lipid Peroxidation; Lipoproteins, LDL; Liver; Magnetic Resonance Spectroscopy; Male; Malondialdehyde; Mass Spectrometry; Mice; Microsomes, Liver; Models, Chemical; Oxidants; Oxygen; Pyridoxal; Rats; Rats, Wistar; Reactive Oxygen Species; Spectrophotometry; Spectrophotometry, Infrared; Superoxides; Time Factors

Vitamin C exists in two major forms. The charged form, ascorbic acid (AA), is taken up into cells via sodium-dependent facilitated transport. The uncharged form, dehydroascorbate (DHA), enters cells via glucose transporters (GLUT) and is then converted back to AA within these cells. Cell types such as certain endothelial and epithelial cells as well as neurons that are particularly prone to damage during diabetes tend to be those that appear to be dependent on GLUT transport of DHA rather than sodium-dependent AA uptake. We hypothesize that diabetic neuropathies, nephropathies and retinopathies develop in part by exclusion of DHA uptake by GLUT transporters when blood glucose levels rise above normal. AA plays a central role in the antioxidant defense system. Exclusion of DHA from cells by hyperglycemia would deprive the cells of the central antioxidant, worsening the hyperglycemia-induced oxidative stress level. Moreover, AA participates in many cellular oxidation-reduction reactions including hydroxylation of polypeptide lysine and proline residues and dopamine that are required for collagen production and metabolism and storage of catecholamines in neurons. Increase in the oxidative stress level and metabolic perturbations can be expected in any tissue or cell type that relies exclusively or mainly on GLUT for co-transport of glucose and DHA including neurons, epithelial cells, and vascular tissues. On the other hand, since DHA represents a significant proportion of total serum ascorbate, by increasing total plasma ascorbate concentrations during hyperglycemia, it should be possible to correct the increase in the oxidative stress level and metabolic perturbations, thereby sparing diabetic patients many of their complications.

Topics: Ascorbic Acid; Biological Transport; Blood Glucose; Dehydroascorbic Acid; Diabetes Mellitus; Diabetic Nephropathies; Diabetic Neuropathies; Diabetic Retinopathy; Endothelium; Humans; Kidney; Models, Biological; Monosaccharide Transport Proteins; Nervous System; Oxidative Stress; Retina

Gender-related differences in the rate of coronary heart disease (CHD) between premenopausal women and men are greatly diminished in women with diabetes mellitus (DM). This may be related, in part, to altered platelet function in premenopausal diabetic women. Hyperglycemia may contribute to increase platelet aggregation through enhancement of oxidative stress, increased nitric oxide (NO) destruction, and increased myosin light-chain (MLC) phosphorylation (MLC-P). Accordingly, we investigated functional and biochemical parameters of platelet function in 32 women (14 premenopausal and postmenopausal controls and 18 age-matched patients with DM); platelet MLC-P and cyclic guanosine monophosphate ([cGMP] reflecting NO) were assessed. Other parameters including age, body mass index (BMI), waist to hip ratio, total cholesterol, and platelet count were not different in the control and diabetic groups. In the premenopausal women, baseline MLC-P was lower in women with DM versus the control group (P = .02). GMP levels were similar in the two groups at baseline (22.7 +/- 3 fmol/mL in controls v 23.1 +/- 3 fmol/mL in diabetic subjects) and 3 minutes after insulin exposure. The platelet content of ascorbic acid (AA), an endogenous antioxidant compound, was elevated in premenopausal women with DM (P = .02) compared with the controls. Despite similar estradiol (beta,E2) levels, platelets of premenopausal women with DM exhibited reduced MLC-P. This paradoxic difference may be accounted for by an increase in platelet AA, as this suggests decreased platelet oxidative stress in this patient population. These observations indicate that an altered redox state and associated MLC-P of platelets does not contribute to enhanced platelet aggregation and CHD in premenopausal women with DM.

Topics: Adolescent; Adult; Aged; Anthropometry; Ascorbic Acid; Blood Platelets; Cyclic GMP; Diabetes Mellitus; Female; Glutathione; Glutathione Disulfide; Humans; Immunoblotting; Matched-Pair Analysis; Middle Aged; Myosin Light Chains; Nitric Oxide; Oxidative Stress; Phosphorylation; Postmenopause; Premenopause; Radioimmunoassay

Topics: Analysis of Variance; Animals; Ascorbic Acid; Diabetes Mellitus; Lipid Peroxidation; Male; Oxidation-Reduction; Rats; Rats, Wistar; Retina

Topics: Ascorbic Acid; Blood Pressure; Diabetes Mellitus; Humans

The advanced glycation end-product (AGE) hypothesis proposes that accelerated chemical modification of proteins by glucose during hyperglycemia contributes to the pathogenesis of diabetic complications. The two most commonly measured AGEs, N(epsilon)-(carboxymethyl)lysine and pentosidine, are glycoxidation products, formed from glucose by sequential glycation and autoxidation reactions. Although several compounds have been developed as AGE inhibitors and are being tested in animal models of diabetes and in clinical trials, the mechanism of action of these inhibitors is poorly understood. In general, they are thought to function as nucleophilic traps for reactive carbonyl intermediates in the formation of AGEs; however alternative mechanisms of actions, such as chelation, have not been rigorously examined. To distinguish between the carbonyl trapping and antioxidant activity of AGE inhibitors, we have measured the chelating activity of the inhibitors by determining the concentration required for 50% inhibition of the rate of copper-catalyzed autoxidation of ascorbic acid in phosphate buffer. All AGE inhibitors studied were chelators of copper, as measured by inhibition of metal-catalyzed autoxidation of ascorbate. Apparent binding constants for copper ranged from approximately 2 mm for aminoguanidine and pyridoxamine, to 10-100 microm for carnosine, phenazinediamine, OPB-9195 and tenilsetam. The AGE-breakers, phenacylthiazolium and phenacyldimethylthiazolium bromide, and their hydrolysis products, were among the most potent inhibitors of ascorbate oxidation. We conclude that, at millimolar concentrations of AGE inhibitors used in many in vitro studies, inhibition of AGE formation results primarily from the chelating or antioxidant activity of the AGE inhibitors, rather than their carbonyl trapping activity. Further, at therapeutic concentrations, the chelating activity of AGE inhibitors and AGE-breakers may contribute to their inhibition of AGE formation and protection against development of diabetic complications.

Topics: Amines; Antioxidants; Ascorbic Acid; Bromides; Chelating Agents; Copper; Diabetes Complications; Diabetes Mellitus; Enzyme Inhibitors; Glycation End Products, Advanced; Guanidines; Oxidation-Reduction; Pyridoxamine; Serum Albumin, Bovine

Taurine is actively transported at the retinal pigment epithelial (RPE) apical membrane in an Na(+)- and Cl(-)-dependent manner. Diabetes may alter the function of the taurine transporter. Because nitric oxide (NO) is a molecule implicated in the pathogenesis of diabetes, we asked whether NO would alter the activity of the taurine transporter in cultured ARPE-19 cells. The activity of the transporter was stimulated in the presence of the NO donor 3-morpholinosydnonimine. The stimulatory effects of 3-morpholinosydnonimine were not observed during the initial 16-h treatment; however, stimulation of taurine uptake was elevated dramatically above control values with 20- and 24-h treatments. Kinetic analysis revealed that the stimulation was associated with an increase in the maximal velocity of the transporter with no significant change in the substrate affinity. The NO-induced increase in taurine uptake was inhibited by actinomycin D and cycloheximide. RT-PCR analysis and nuclear run-on assays provided evidence for upregulation of the transporter gene. This study provides the first evidence of an increase in taurine transporter gene expression in human RPE cells cultured under conditions of elevated levels of NO.

Topics: Animals; Antioxidants; Ascorbic Acid; Carrier Proteins; Cell Line; Diabetes Mellitus; Dose-Response Relationship, Drug; Glutathione; Humans; Immunohistochemistry; Membrane Glycoproteins; Membrane Transport Proteins; Methylene Blue; Mice; Mice, Inbred ICR; Molsidomine; Nitric Oxide; Nitric Oxide Donors; Nitroprusside; Pigment Epithelium of Eye; Protein Synthesis Inhibitors; Taurine; Time Factors; Tyrosine

The association between dietary and lifestyle factors and intermittent claudication was investigated in the Finnish Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study. The cohort comprised 26,872 male smokers aged 50-69 years who were free of claudication at study entry. At baseline (1985-1988), subjects completed a diet history questionnaire. During a median follow-up period of 4 years (ending in spring 1993), 2,578 men reported symptoms of claudication on the Rose questionnaire, which was administered annually. Smoking status was assessed every 4 months. Smoking, systolic blood pressure, serum total cholesterol, and diabetes mellitus were positively associated with risk for claudication, whereas serum high density lipoprotein cholesterol, education, and leisure time exercise were inversely associated with risk. Dietary carbohydrates, fiber, and n-6 polyunsaturated fatty acids were inversely associated with risk for claudication, as were some dietary and serum antioxidants: dietary vitamin C (highest quartile vs. lowest: relative risk (RR) = 0.86; 95% confidence interval (CI): 0.77, 0.97), dietary gamma-tocopherol (RR = 0.89; 95% CI: 0.79, 1.00), dietary carotenoids (RR = 0.82; 95% CI: 0.73, 0.92), serum alpha-tocopherol (RR = 0.88; 95% CI: 0.77, 1.00), and serum beta-carotene (RR = 0.77; 95% CI: 0.68, 0.86). Smoking cessation reduced subsequent risk for claudication (RR = 0.86; 95% CI: 0.75, 0.99). The authors conclude that classical risk factors for atherosclerosis are associated with claudication. High intakes of antioxidant vitamins may be protective. Further research is needed before antioxidants can be recommended for the prevention of intermittent claudication.

Topics: Administration, Oral; Age Distribution; Aged; Ascorbic Acid; beta Carotene; Blood Pressure; Cholesterol; Cholesterol, HDL; Cohort Studies; Comorbidity; Diabetes Mellitus; Dietary Supplements; Energy Metabolism; Finland; Humans; Incidence; Intermittent Claudication; Life Style; Male; Middle Aged; Multivariate Analysis; Prospective Studies; Risk Assessment; Risk Factors; Smoking; Smoking Cessation; Vitamin A; Vitamin E

To examine the cross-sectional association between plasma vitamin C, self-reported diabetes, and HbA1c.. Data from a population-based study of diet, cancer, and chronic disease were analyzed. A total of 2,898 men and 3,560 women 45-74 years of age who were registered with general practices in Norfolk, U.K., were recruited to the European Prospective Investigation Into Cancer-Norfolk study between 1995 and 1998.. Mean plasma vitamin C levels were significantly higher in individuals with HbA1c levels < 7% than in those with self-reported diabetes or prevalent undiagnosed hyperglycemia (HbA1c > or = 7%). An inverse gradient of mean plasma vitamin C was found in both sexes across quintiles of HbA1c distribution < 7%. The odds ratio (95% CI) of having prevalent undiagnosed hyperglycemia per 20 micromol/l (or 1 SD) increase in plasma vitamin C was 0.70 (0.52-0.95) (adjusted for sex, age, BMI, waist-to-hip ratio, tertiary education, any use of dietary supplements, vegetarian diet, alcohol consumption, physical activity, dietary vitamin E, dietary fiber, dietary saturated fat, and smoking history). The unadjusted change in HbA1c per 20 micromol/l increase in vitamin C estimated by linear regression was -0.12% (-0.14 to -0.09) in men and -0.09% (-0.11 to -0.07) in women. After adjusting for the possible confounders, these values were -0.08% (-0.11 to -0.04) in men and -0.05% (-0.07 to -0.03) in women.. An inverse association was found between plasma vitamin C and HbA1c. Dietary measures to increase plasma vitamin C may be an important public health strategy for reducing the prevalence of diabetes.

Topics: Aged; Ascorbic Acid; Chronic Disease; Cohort Studies; Cross-Sectional Studies; Diabetes Mellitus; Diet; England; Europe; Female; Glycated Hemoglobin; Humans; Hyperglycemia; Male; Middle Aged; Neoplasms; Odds Ratio; Prevalence

Non-enzymatic glycation, accompanied by the formation of free radicals, represents a serious problem in diabetes mellitus. It is supposed to be the cause of the development of long-term diabetic complications. The aim of this work was to estimate the effect of treatment with vitamin C (1 g per day) and E (600 mg per day) on selected biochemical parameters as well as to determine the physicochemical state of erythrocyte membranes in diabetics. The paper also compares the physicochemical state of diabetic and control erythrocyte membranes. The changes in the values of glycaemia, glycated haemoglobin, and fructosamine were insignificant after three months of treatment. This points out that the doses used could be low or that the patient compliance was poor. An anionic fluorescent probe merocyanine 540 (MC540) was used to monitor possible changes in the physicochemical properties of isolated diabetic erythrocyte membranes. Significantly higher affinity of MC540 monomers to the membrane in diabetics treated with vitamin E was observed, which can be the result of the antioxidative effect of the vitamin (p < 0.02). A comparison of absorption spectra of MC540 in diabetic and control membranes revealed significant changes in the position of the bands and in their absorbances (p < 0.01 and less). They result from substantial alterations in the structure, surface charge, and the fluidity of erythrocyte membranes in diabetes mellitus. (Tab. 2, Fig. 3, Ref. 22.)

Topics: Antioxidants; Ascorbic Acid; Blood Glucose; Diabetes Mellitus; Erythrocyte Membrane; Fructosamine; Glycated Hemoglobin; Glycosylation; Humans; Middle Aged; Vitamin E

Increased oxidative stress has been suggested to be involved in the pathogenesis and progression of diabetic tissue damage. Several antioxidants have been described as beneficial for oxidative stress-associated diseases. Boldine ([s]-2,9-dihydroxy-1, 10-dimethoxyaporphine) is a major alkaloid found in the leaves and bark of boldo (Peumus boldus Molina), and has been shown to possess antioxidant activity and anti-inflammatory effects. From this point of view, the possible anti-diabetic effect of boldine and its mechanism were evaluated. The experiments were performed on male rats divided into four groups: control, boldine (100 mg kg(-1), daily in drinking water), diabetic [single dose of 80 mg kg(-1)of streptozotocin (STZ), i.p.] and diabetic simultaneously fed with boldine for 8 weeks. Diabetic status was evaluated periodically with changes of plasma glucose levels and body weight in rats. The effect of boldine on the STZ-induced diabetic rats was examined with the formation of malondialdehydes and carbonyls and the activities of endogenous antioxidant enzymes (superoxide dismutase and glutathione peroxidase) in mitochondria of the pancreas, kidney and liver. The scavenging action of boldine on oxygen free radicals and the effect on mitochondrial free-radical production were also investigated. The treatment of boldine attenuated the development of hyperglycemia and weight loss induced by STZ injection in rats. The levels of malondialdehyde (MDA) and carbonyls in liver, kidney and pancreas mitochondria were significantly increased in STZ-treated rats and decreased after boldine administration. The activities of mitochondrial manganese superoxide dismutase (MnSOD) in the liver, pancreas and kidney were significantly elevated in STZ-treated rats. Boldine administration decreased STZ-induced elevation of MnSOD activity in kidney and pancreas mitochondria, but not in liver mitochondria. In the STZ-treated group, glutathione peroxidase activities decreased in liver mitochondria, and were elevated in pancreas and kidney mitochondria. The boldine treatment restored the altered enzyme activities in the liver and pancreas, but not the kidney. Boldine attenuated both STZ- and iron plus ascorbate-induced MDA and carbonyl formation and thiol oxidation in the pancreas homogenates. Boldine decomposed superoxide anions, hydrogen peroxides and hydroxyl radicals in a dose-dependent manner. The alkaloid significantly attenuated the production of superoxide anions, hydrogen

Topics: Animals; Aporphines; Ascorbic Acid; Blood Glucose; Body Weight; Diabetes Mellitus; Drug Interactions; Free Radicals; Iron; Lipid Peroxidation; Male; Mitochondria; Nitric Oxide; Oxidation-Reduction; Oxidative Stress; Pancreas; Protective Agents; Rats; Rats, Sprague-Dawley; Reactive Oxygen Species; Streptozocin; Sulfhydryl Compounds; Superoxide Dismutase

Rates of vitamin-mineral supplement use by US female physicians are unknown but are of particular interest for several epidemiologic and clinical reasons.. The objective was to determine rates of and variations in vitamin-mineral supplement use among US female physicians.. We used data from the Women Physicians' Health Study, a large (n = 4501) national, randomly sampled mail survey of female physicians aged 30-70 y.. Half of the physicians took a multivitamin-mineral supplement; 35.5% of these did so regularly. However,

Topics: Adult; Aged; Ascorbic Acid; Calcium; Cohort Studies; Coronary Disease; Diabetes Mellitus; Dietary Supplements; Female; Humans; Marital Status; Middle Aged; Minerals; Neoplasms; Osteoporosis; Physicians, Women; Social Class; Surveys and Questionnaires; Vitamin A; Vitamin E; Vitamins

Previous studies suggested that diabetes mellitus may lower serum vitamin C concentrations, but most of these studies used clinic-based populations with established diabetes of varying duration and did not adjust for important covariates.. Using a population-based sample and adjusting for important covariates, we asked whether serum vitamin C concentrations in persons with newly diagnosed diabetes differed from those in persons without diabetes.. Data were obtained from the third National Health and Nutrition Examination Survey (1988-1994). Serum vitamin C was assayed by using reversed-phase HPLC with multiwavelength detection. Diabetes status (n = 237 persons with diabetes; n = 1803 persons without diabetes) was determined by oral-glucose-tolerance testing of the sample aged 40-74 y.. After adjustment for age and sex, mean serum vitamin C concentrations were significantly lower in persons with newly diagnosed diabetes than in those without diabetes. After adjustment for dietary intake of vitamin C and other important covariates, however, mean concentrations did not differ according to diabetes status.. When assessing serum vitamin C concentrations by diabetes status in the future, researchers should measure and account for all factors that influence serum vitamin C concentrations.

Topics: Adult; Aged; Aging; Ascorbic Acid; Blood Glucose; Diabetes Mellitus; Educational Status; Exercise; Female; Humans; Insulin; Male; Middle Aged; Nutrition Surveys; Smoking

Topics: Aqueous Humor; Ascorbic Acid; Diabetes Mellitus; Electrophoresis, Capillary; Humans; Reference Values; Reproducibility of Results; Uric Acid; Uveitis, Anterior

Pathogenesis of diabetes-related microvascular complications involving oxidative damage by free radicals has been demonstrated. Free radical generation has been shown to derive largely from iron. Our objectives, therefore, were to determine if there is an increased incidence and/or an accelerated course of nephropathy in patients with diabetes, secondary to transfusional hemochromatosis, and to examine whether free radical activity contributes to the development of this complication.. We evaluated nine patients with homozygous beta-thalassemia, complicated by clinically overt diabetes, for diabetic nephropathy over a 7-year period. Lipid peroxidation was quantified by measuring the presence of 20 saturated and unsaturated aldehydes, and results were compared with five normotensive type 1 diabetic patients without iron overload.. Nephropathy developed in five of nine patients (55%) after a mean duration of overt diabetes of 3.6 +/- 2.0 years. Three patients showed evidence of progressive microalbuminuria over a 7-year period (24.7-46.2, 52.2-430.1, and 17.7-54.3 micrograms/min, respectively). Two patients with borderline microalbuminuria (19.9 and 14.5 micrograms/min, respectively) demonstrated stable albumin excretion rates over the follow-up period. Total aldehyde concentration was significantly higher in beta-thalassemia diabetic patients, compared with nonthalassemic diabetic control subjects (8,106 +/- 1,280 vs. 4,594 +/- 247 nmol/l; P < 0.0001). The three patients with progressive microalbuminuria demonstrated significantly higher total aldehyde concentration, compared with the other beta-thalassemia diabetic patients with stable albumin excretion (9,428 +/- 337 vs. 7,445 +/- 1,003 nmol/l; P < 0.01). Serum vitamin E concentrations were significantly lower in beta-thalassemia patients with diabetes, compared with diabetic patients without iron overload (12.1 +/- 6.0 vs. 25.9 +/- 11.4 mumol/l; P = 0.02). Serum vitamin C concentrations did not differ between the two groups. Multiple regression analysis demonstrated total aldehyde concentration to be the most significant predictor for the development of microalbuminuria (P = 0.01), followed by the duration of diabetes (P = 0.02) and glycemic control (P = 0.02).. Early development and an accelerated course of diabetic nephropathy in iron-loaded patients with beta-thalassemia are observed. These findings may be attributed to high oxidative stress in these patients, which is secondary to iron-derived free radicals and to the patients' diminished antioxidant reserves.

Topics: Adult; Albuminuria; Aldehydes; Antioxidants; Ascorbic Acid; beta-Thalassemia; Blood Glucose; Blood Pressure; Diabetes Complications; Diabetes Mellitus; Diabetic Nephropathies; Fructosamine; Homozygote; Humans; Iron; Kidney Function Tests; Lipid Peroxidation; Oxidative Stress; Retrospective Studies; Transfusion Reaction; Vitamin E

The present investigations arose from our interest in the possibility that some structures which arise secondary to protein glycation might bind transition metals such as iron and copper. In support of this we find that, when glycated, three different proteins--albumin, gelatin (a soluble collagen fragment) and elastin--all gain a substantial affinity for the transition metals iron and copper. The glycated proteins bind at least three times as much iron as do the non-glycated proteins. Similarly, glycated albumin and gelatin also bind 2-3 times as much copper. Furthermore, at least in the case of copper bound to glycated albumin, the bound metal retains redox activity and participates in the catalytic oxidation of ascorbic acid. Should similar "glycochelates" form in vivo in diabetics, reactions mediated by these chelates may be involved in certain complications of diabetes.

Topics: Albumins; Ascorbic Acid; Chelating Agents; Copper; Diabetes Complications; Diabetes Mellitus; Elastin; Gelatin; Humans; Iron; Oxidation-Reduction; Protein Binding

Topics: Adult; Antioxidants; Ascorbic Acid; Calcinosis; Diabetes Mellitus; Diabetes Mellitus, Type 2; DNA Damage; Erythrocytes; Humans; Nutrition Disorders; Oxidative Stress; Pancreatic Diseases; Vitamin A; Vitamin E

Topics: Animals; Antioxidants; Ascorbic Acid; Diabetes Mellitus; Diabetes Mellitus, Experimental; Glucose; Humans; Methionine; Oxidative Stress; Vitamin E

The present study was to investigate the levels of plasma lipid peroxide products including malondialdehyde (MDA) and conjugated dienes (CD), and antioxidants including enzyme superoxide dismutase, glutathione peroxidase, catalase, plasma vitamin E and vitamin C in diabetic patients. Fifty-eight diabetic subjects; 16 males and 42 females, aged 30-75 years, were recruited. Eighteen of them had diabetes and forty of them had diabetes with hyperlipidemia. Twenty-seven healthy subjects, 8 males and 19 females, aged 30-75 years, were used as the control group. The results showed that the concentrations of plasma MDA in diabetic patients with or without hyperlipidemia tended to be increased when compared to the controls but there were no significant differences. The CD values were increased significantly in both diabetic groups when compared with control subjects. Significantly elevated levels of plasma MDA and CD were found in diabetic patients with hypertriglyceridemia (> 150 mg%). This increment did not change the antioxidant status in both enzymes and vitamins except that the plasma vitamin E levels and the ratios of tocopherol: cholesterol were increased significantly. An increase of lipid peroxide in plasma may be one important factor in the development of vascular complication and atherosclerosis seen in diabetic patients.

Topics: Adult; Aged; Antioxidants; Arteriosclerosis; Ascorbic Acid; Cardiovascular Diseases; Catalase; Diabetes Mellitus; Female; Glutathione Peroxidase; Humans; Hyperlipidemias; Lipid Peroxidation; Male; Malondialdehyde; Middle Aged; Superoxide Dismutase; Vitamin E

Plasma concentrations of the antioxidant vitamin ascorbic acid were measured by high-performance liquid chromatography in critically ill patients in whom the excessive generation of reactive oxygen species could compromise antioxidant defense mechanisms. Median concentrations of both total vitamin C (ascorbic acid and dehydroascorbic acid) and ascorbic acid in these patients were < 25% (P < 0.001) of the values found in healthy control subjects and in subjects in two other disease groups (diabetes, gastritis) in which reactive oxygen species are reported to be increased. The low values could not be explained by age, sex, intake, or treatment differences, but were associated with the severity of the illness and were not prevented by the use of parenteral nutrition containing ascorbic acid. In addition, the vitamin was less stable in blood samples taken from critically ill patients than in similar samples from subjects in the other groups. The findings indicate that antioxidant defenses could be considerably compromised in these very sick patients. If this reduces the patient's capacity to scavenge reactive species, then the potential of these species to damage DNA and lipid membranes could be increased and compromise recovery.

Topics: Adult; Aged; Aging; Ascorbic Acid; Chromatography, High Pressure Liquid; Critical Illness; Dehydroascorbic Acid; Diabetes Mellitus; Female; Gastritis; Humans; Intensive Care Units; Male; Middle Aged; Reactive Oxygen Species

Latent scurvy is characterized by a reversible atherosclerosis that closely resembles the clinical form of this disease. Acute scurvy is characterized by microvascular complications such as widespread capillary hemorrhaging. Vitamin C (ascorbate) is required for the synthesis of collagen, the protein most critical in the maintenance of vascular integrity. We suggest that in latent scurvy, large blood vessels use modified LDL--in particular lipoprotein(a)--in addition to collagen to maintain macrovascular integrity. By this mechanism, collagen is spared for the maintenance of capillaries, the sites of gas and nutrient exchange. The foam-cell phenotype of atherosclerosis is identified as a mesenchymal genetic program, regulated by the availability of ascorbate. When vitamin C is limited, foam cells develop and induce oxidative modification of LDL, thereby stabilizing large blood vessels via the deposition of LDL. The structural similarity between vitamin C and glucose suggests that hyperglycemia will inhibit cellular uptake of ascorbate, inducing local vitamin C deficiency.

Topics: Animals; Arteriosclerosis; Ascorbic Acid; Collagen; Diabetes Complications; Diabetes Mellitus; Foam Cells; Humans; Hyperglycemia; Lipoprotein(a); Metaplasia; Models, Biological; Scurvy

Topics: Adult; Aged; Aged, 80 and over; Ascorbic Acid; Cardiovascular Diseases; Cataract; Copper; Diabetes Mellitus; Diet; Humans; Lens, Crystalline; Middle Aged; Oxidation-Reduction; Peptides; Reference Values; Regression Analysis; Tryptophan

Topics: Aging; Ascorbic Acid; Beverages; Bone Diseases; Citrates; Citric Acid; Diabetes Mellitus; Drug Synergism; Fruit; Hemosiderosis; Humans; Iron; Neoplasms; Oxidative Stress

Erythrocytes exposed to ascorbic acid in the presence of aminotriazole undergo a dose- and time-dependent inactivation of endogenous catalase which is proportional to environmental hydrogen peroxide (H2O2) concentrations. The production of H2O2 seems to be dependent upon the availability of transition metal chelatable by o-phenanthroline (OPT), although the kinetics of catalase inactivation and H2O2 production by externally added copper ions in the presence of OPT is complex. Furthermore, although glucose is also able to undergo a transition-metal-catalysed oxidation yielding H2O2, the production of H2O2 by glucose seems to be a minor process by comparison with ascorbic acid oxidation. Indeed, on the basis of these data, transition-metal-catalysed ascorbic acid oxidation is likely to be a more important source of oxidative stress in the diabetic state than hyperglycaemia.

Topics: Amitrole; Ascorbic Acid; Catalase; Diabetes Mellitus; Erythrocytes; Glucose; Humans; Hydrogen Peroxide; Kinetics; Metals; Oxidative Stress

We describe a simplified method for studying the susceptibility to in vitro autoxidation of lipoproteins containing apolipoprotein B. It comprises copper induced autoxidation of VLDL+LDL plasma fractions and an assay for thiobarbituric acid reactive soluble substances. We studied autoxidation of VLDL+LDL in a population of 30 healthy subjects and a population of 30 diabetic patients. No significant difference in susceptibility to autoxidation could be detected. Protection afforded by ascorbic acid amounted to more than 95% at concentrations easily attainable in vivo by oral supplementation. Thiobarbituric acid reactive substances were higher in plasma from diabetic patients: 0.51 +/- 0.25 mumol/l vs 0.35 +/- 0.07 mumol/l for control subjects (p < 0.001). Our data confirm the presence of higher levels of lipid peroxides in diabetic patients, but fail to demonstrate any difference in susceptibility to oxidation of apolipoprotein B containing particles between control and diabetic subjects.

Topics: Apolipoproteins B; Ascorbic Acid; Copper; Copper Sulfate; Diabetes Mellitus; Erythrocytes; Female; Humans; Lipid Peroxidation; Lipoproteins, LDL; Lipoproteins, VLDL; Male; Middle Aged; Oxidation-Reduction; Spectrophotometry, Ultraviolet; Thiobarbituric Acid Reactive Substances

Risk factors for pancreatic cancer were examined in a cohort study of 13,979 residents of a retirement community. After 9 years of follow-up, 65 incident cases of pancreatic cancer were identified. An increased risk of pancreatic cancer was associated with a history of diabetes and cholecystectomy. Higher intake of vegetables, fruits, dietary beta-carotene, and vitamin C were each associated with a reduced risk of pancreatic cancer, although none of these associations was statistically significant. Risk of pancreatic cancer decreased with increasing tea consumption but was unrelated to coffee consumption. No strong or consistent association was seen between either smoking or alcohol consumption and risk of pancreatic cancer, but a consistent and significant increase in risk followed cholecystectomy.

Topics: Aged; Aged, 80 and over; Alcohol Drinking; Ascorbic Acid; beta Carotene; Carotenoids; Cholecystectomy; Coffee; Cohort Studies; Diabetes Mellitus; Diet; Female; Follow-Up Studies; Fruit; Humans; Incidence; Male; Pancreatic Neoplasms; Prospective Studies; Risk Factors; Smoking; Tea; Vegetables

Plasma lipid and apolipoprotein (apo) A-I and B concentrations and habitual dietary intakes were determined in 306 free-living elderly individuals (119 men and 187 women, age range 60-100 y). Plasma lipid and apo A-I concentrations were significantly higher in women than in men. In older men, plasma triglyceride, total cholesterol, and apo B concentrations were significantly lower than in younger men, whereas a significant trend towards lower LDL-cholesterol concentrations was observed in older women. Energy intake and percent macronutrient intake were not influenced by age. Higher carbohydrate intake was associated with lower HDL cholesterol and apo A-I concentrations, whereas higher total fat intake was associated with higher apo A-I concentrations. Higher vitamin A intake was associated with higher plasma concentrations of HDL cholesterol and apo A-I. Our data indicate that both dietary and plasma concentrations of vitamin A, body mass index, age, and sex are important determinants of plasma lipid concentrations in the elderly.

Topics: Aged; Aged, 80 and over; Analysis of Variance; Apolipoproteins; Ascorbic Acid; Body Mass Index; Body Weight; Coronary Disease; Diabetes Mellitus; Diet; Diet Surveys; Female; Humans; Hypertension; Lipids; Lipoproteins; Male; Middle Aged; Vitamin A

Studies indicate that large doses of all-rac-alpha-tocopherol in people with diabetes or ascorbic acid in nondiabetic subjects reduces protein glycosylation. The mechanisms by which these nutrients influence glycosylation are poorly understood but may be related to their ability to function as antioxidants. We examined the relationship between glycosylated hemoglobin (GHb) and intake of vitamins E and C and beta-carotene in a population-based sample of middle-aged and older adults participating in the Beaver Dam Eye Study. In people with diabetes, no significant associations were observed between GHb and intake of vitamins E and C and beta-carotene. In people without diabetes, energy-adjusted vitamin C intake was negatively associated with GHb after age and sex were controlled for (dietary, P = 0.02; total, P = 0.04). No significant relationships between GHb and intake of vitamin E and beta-carotene were observed.

Topics: Adult; Aged; Aged, 80 and over; Aging; Ascorbic Acid; beta Carotene; Carotenoids; Diabetes Mellitus; Diet; Female; Glycated Hemoglobin; Humans; Male; Middle Aged; Osmolar Concentration; Vitamin E

The exposure of mouse peritoneal macrophages to cholesterol linoleate-containing artificial lipoproteins can lead to intracellular ceroid accumulation. This can be used as a model to study the role of oxidation in macrophage uptake of lipoproteins containing unsaturated fatty acids, considered by many as a primary event in atherosclerotic plaque formation. Our studies show that ascorbic acid can both inhibit and promote the formation of ceroid in such a model system. The transition metal copper (Cu(II)) further elevates ceroid accumulation and EDTA, a metal chelator, inhibits it. When trace levels of transition metals are present, low concentrations of ascorbic acid can elevate ceroid formation. This pro- and antioxidant characteristic of ascorbic acid was confirmed by monitoring the generation of oxidants by various concentrations of ascorbic acid, assessed by benzoic acid hydroxylation or the fragmentation of BSA. We discuss these observations in the context of an apparent increase in ascorbic acid oxidation and elevated severity of atherosclerosis in diabetes mellitus.

Topics: Animals; Arteriosclerosis; Ascorbic Acid; Cells, Cultured; Ceroid; Cholesterol Esters; Copper; Diabetes Complications; Diabetes Mellitus; Edetic Acid; Humans; Macrophages; Male; Mice; Mice, Inbred BALB C; Oxidation-Reduction; Serum Albumin, Bovine

Transition metal-catalysed oxidations have been implicated in the complications of diabetes. We report here that some experimental inhibitors of the enzyme aldose reductase (implicated in diabetes mellitus via its ability to catalyse glucose reduction to sorbitol) are also potent inhibitors of transition metal-catalysed ascorbate oxidation. The inhibition appears to be dependent upon the presence of a spirohydantoin group. It is conceivable that the copper- and iron-binding capacity of these compounds may contribute to some of their observed biological effects and may provide a starting point for a new generation of experimental drugs for the treatment of diabetes mellitus.

Topics: Aldehyde Reductase; Antioxidants; Ascorbic Acid; Copper; Diabetes Mellitus; Dose-Response Relationship, Drug; Fluorenes; Humans; Hydantoins; Imidazoles; Imidazolidines; Iron; Oxidation-Reduction; Structure-Activity Relationship

Ascorbic acid (AA), dehydroascorbic acid (DHAA), and vitamin E were measured in tissues and plasma of 30 control and 30 spontaneously diabetic BioBreeding rats (BBdp) during development and before the onset of diabetes. At weaning, rats were fed an AIN-76 semisynthetic diet for 30, 64, or 113 days, after which plasma and tissues from 10 rats of each group were collected and analysed for AA, DHAA, and vitamin E. AA and DHAA levels were significantly increased in plasma and spleen of the diabetes-prone rats compared with those of the control group at 30 and 64 days, but the difference disappeared by 113 days. No differences were observed in liver, adrenals, thymus, and pancreas at any of the time periods. However, lower levels of vitamin E were observed in adrenal gland, thymus, and pancreas of the diabetes-prone rats. It is concluded that BBdp rats have an altered metabolism of AA, DHAA, and vitamin E, before the onset of diabetes. These changes could be due to genetic and physiological factors operating during development of this rat strain.

Topics: Adrenal Glands; Animals; Ascorbic Acid; Body Weight; Diabetes Mellitus; Male; Pancreas; Rats; Rats, Inbred BB; Spleen; Thymus Gland; Time Factors; Vitamin E

Reactions between glucose and protein are held to be responsible for the protein 'browning' reactions which occur in diabetes mellitus. In vitro, however, the formation of such novel protein fluorophores is dependent upon the metal-catalysed oxidation of the monosaccharide (glucose 'autoxidation'). Since other small oxidisable molecules are capable of 'browning' proteins via similar metal-catalysed oxidative mechanisms we suggest that protein modification in diabetes may not be restricted to reactions with monosaccharides but may also include other small autoxidisable molecules.

Topics: Arachidonic Acid; Arachidonic Acids; Ascorbic Acid; Crystallins; Diabetes Mellitus; Glucose; In Vitro Techniques; Maillard Reaction; Oxidation-Reduction; Proteins; Serum Albumin, Bovine; Spectrometry, Fluorescence

The concept that lipoprotein(a) [Lp(a)] is a surrogate for ascorbate is suggested by the fact that this lipoprotein is found generally in the blood of primates and the guinea pig, which have lost the ability to synthesize ascorbate, but only rarely in the blood of other animals. Properties of Lp(a) that are shared with ascorbate, in accordance with this hypothesis, are the acceleration of wound healing and other cell-repair mechanisms, the strengthening of the extracellular matrix (e.g., in blood vessels), and the prevention of lipid peroxidation. High plasma Lp(a) is associated with coronary heart disease and other forms of atherosclerosis in humans, and the incidence of cardiovascular disease is decreased by elevated ascorbate. Similar observations have been made in cancer and diabetes. We have formulated the hypothesis that Lp(a) is a surrogate for ascorbate in humans and other species and have marshaled the evidence bearing on this hypothesis.

Topics: Animals; Antioxidants; Arteriosclerosis; Ascorbic Acid; Biological Evolution; Cardiovascular Diseases; Diabetes Mellitus; Disease Models, Animal; Humans; Lipoprotein(a); Lipoproteins; Neoplasms; Wound Healing

Ascorbic acid is required in the synthesis of collagen and is also an important anti-oxidant. In a previous study, plasma ascorbic acid concentration was found to be decreased in diabetic patients but there was no relationship with blood glucose level. In the current study of diabetic patients, both plasma ascorbic acid and its urinary excretion correlated inversely with glycosylated hemoglobin level. Plasma ascorbic acid was also lower in diabetic rats but urinary ascorbic acid was elevated. The divergent trend in urinary ascorbic acid excretion observed in diabetic patients and diabetic rats may be due to difference in the ability of these two species to synthesize ascorbic acid. Difference in renal reabsorption of ascorbic acid may also be a relevant factor. The lower plasma and urinary ascorbic acid levels in diabetic patients with more severe hyperglycaemia indicates that this group of patients is particularly at risk of developing deficiency of this vitamin. As ascorbic acid has many important functions in the body, it may be necessary to supplement this vitamin in patients with chronically poorly controlled diabetes.

Topics: Adult; Animals; Ascorbic Acid; Diabetes Mellitus; Diabetes Mellitus, Experimental; Disease Models, Animal; Female; Humans; Middle Aged; Rats; Rats, Inbred Strains

Hyperglycemia and/or hypoinsulinemia have been found to inhibit L-ascorbic acid cellular transport. The resultant decrease in intracellular ascorbic acid may de-inhibit aryl sulfatase B and increase degradation of sulfated glycosaminoglycans (sGAG). This could lead to a degeneration of the extracellular matrix and result in increased intimal permeability, the initiating event in atherosclerosis. The present studies show that the glucose transport inhibitor cytochalasin B blocked the uptake of 3H-2-deoxy-D-glucose (2.5 mg%) by mouse 3T3 fibroblasts. Cytochalasin B also blocked the uptake of 14C-L-ascorbic acid (1.25 mg%). The results of these studies further support the hypothesis that glucose and ascorbate share a common transport system. This may have important implications concerning the vascular pathology associated with diabetes mellitus.

Topics: Animals; Ascorbic Acid; Biological Transport; Cell Line; Cytochalasin B; Deoxy Sugars; Deoxyglucose; Diabetes Mellitus; Dose-Response Relationship, Drug; Fibroblasts

Plasma total ascorbate status measured by 2.4 dinitrophenyl hydrazine method showed that diabetics (N = 100) had significantly lower plasma total ascorbate compared with 45 age and sex matched non-diabetic controls; 0.34 +/- 0.16 mg/dl vs 0.68 +/- .06 mg/dl, P less than 0.001) regardless of presence or absence of retinopathy and irrespective of mode of treatment. The finding unique to this study was that plasma total ascorbate status in diabetics with retinopathy (0.19 +/- 0.07 mg/dl) was significantly lower than that of uncomplicated diabetics (0.49 +/- 0.06 mg/dl; P less than 0.001). Plasma Glucose had no correlation with plasma ascorbate levels and effect of duration of Diabetes Mellitus (DM) on ascorbate status in diabetics was ambiguous. Diabetics had abnormally fragile cutaneous capillaries detected by Hess test. The incidence of capillary fragility was more in patients with retinopathy. Hess test can be used as an easy and non-invasive test to assess plasma ascorbate status to detect microvascular involvement in DM. The experience of this study reflects that the two distinct microvascular lesions in diabetes, i.e. abnormal dermal capillary fragility and retinopathy may have a common link to ascorbic acid deficiency. An early switching on of the supplementation of ascorbic acid may retard the development of microvascular complications in diabetes.

Topics: Adult; Ascorbic Acid; Blood Glucose; Diabetes Mellitus; Diabetic Angiopathies; Diabetic Retinopathy; Humans; Middle Aged

The in vitro accumulation of sorbitol by human erythrocytes incubated in a physiological glucose medium was found to be strongly reduced by the addition of ascorbic acid (AA). A maximal inhibition of sorbitol in the erythrocytes of 98.3% occurred when the concentration of AA was at its peak in the cells. After incubation, the erythrocyte sorbitol was found to be inversely correlated with the concentration of AA in the erythrocytes. A human supplementation study was conducted with 10 normoglycemic subjects. Each was given 500 mg/day AA alone or in a citrus fruit medium. Each supplementation lasted 2 wk and was followed by a 10-day washout. The citrus fruit medium produced a significantly greater increase in erythrocyte AA compared with AA alone. AA alone and in citrus fruit medium decreased erythrocyte sorbitol 12.6 and 27.2%, respectively, with the latter being significantly more effective. In a study with 4 subjects, 2000 mg/day AA resulted in a reduction in erythrocyte sorbitol of 56.1%. As in the in vitro study, there was an inverse relationship between erythrocyte AA and sorbitol. Two thousand milligrams of AA per day (AA or citrus fruit medium) was given to 8 diabetic subjects in a preliminary 3-wk supplementation trial in which erythrocyte sorbitol levels were decreased by 44.5%. These results suggest that AA supplementation for diabetic subjects may provide a simple means of preventing and ameliorating the complications of diabetes without the use of drugs.

Topics: Adolescent; Adult; Ascorbic Acid; Diabetes Mellitus; Erythrocytes; Female; Food, Fortified; Humans; Male; Oxidation-Reduction; Sorbitol

Tissues sequester vitamin C in concentrations exceeding that present in plasma. The transmembrane transport mechanisms have been shown to be influenced by the concentration of glucose in vitro. On this basis an impairment of tissue vitamin C status may be present in diabetes mellitus. Recent evidence in support of this hypothesis, first proposed by Mann in 1974, is reviewed.

Topics: Ascorbic Acid; Biological Transport; Dehydroascorbic Acid; Diabetes Mellitus; Humans

Competition for membrane transport between glucose and ascorbic acid (AA) has been shown in vitro in human lymphocytes, granulocytes, and fibroblasts. Therefore, we examined the effects of acute administration of i.v. glucose on AA levels in mononuclear (MNL) and polymorphonuclear leukocytes (PMN) and on leukocyte chemotaxis. Plasma glucose and AA, MNL AA, PMN AA, and chemotaxis by MNL and PMN were measured before and after i.v. glucose in fasted normal male volunteers. A decline in AA occurred in PMN as well as MNL, but decreases in AA induced acutely by transient hyperglycemia were not associated with changes in chemotaxis. However, under conditions of prolonged hyperglycemia maintained by a glucose clamp technique, significant changes (p less than 0.01) in chemotaxis by both PMN and MNL were observed after 210 and 240 min, with changes in chemotaxis to several chemoattractants significantly correlated with decreases in intracellular AA after 240 min (p less than 0.05). These results are consistent with the hypothesis that chronic hyperglycemia may be associated with intracellular deficits of leukocyte AA, an impaired acute inflammatory response, and altered susceptibility to infection and faulty wound repair in patients with diabetes.

Topics: Adult; Aged; Ascorbic Acid; Blood Glucose; Chemotactic Factors; Chemotaxis, Leukocyte; Diabetes Mellitus; Glucose; Humans; Lymphocytes; Male; Middle Aged; Monocytes; Neutrophils

In order to assess different methods for early detection of unsuspected diabetes, urine and venous blood samples were collected at random from 1082 patients visiting a primary health care centre in southern Sweden. Blood glucose was analysed by the hexokinase method along with the Dextrostix-Eyetone reflectance meter. Urine glucose was determined by Clinistix, Diastix, Neostix, Rediatest, Clinitest and quantitatively by the hexokinase method. Patients fulfilling the criteria of a positive screen were subjected to a diagnostic investigation with an oral glucose tolerance test. Out of 89 positive screenees, 37 patients were classified as diabetics, showing a prevalence of diabetes in the study population of 3.4% according to the WHO criteria. Impaired glucose tolerance was found in 14 patients. In a control group of 56 patients, randomly selected among negative screenees, no cases of diabetes were found. Random blood glucose measurement by the hexokinase method, using 7 mmol/l as a screening level, had a significantly higher sensitivity (95%) than all urine glucose methods (59-30%) with comparable specificity (97-99%). Use of the Dextrostix-Eyetone reflectance meter resulted in a decrease in sensitivity to 75% without any change in specificity or predictability, compared with the hexokinase method. Urine testing for glucose was found to be a suboptimal method for early case finding of diabetes among patients receiving primary health care.

Topics: Adolescent; Adult; Aged; Ascorbic Acid; Blood Glucose; Child; Child, Preschool; Diabetes Mellitus; False Negative Reactions; Fasting; Female; Glucose Tolerance Test; Glycosuria; Humans; Infant; Infant, Newborn; Male; Middle Aged; Reagent Strips

Indian and black patients admitted to King Edward VIII and R. K. Khan Hospitals with a diagnosis of cardiac infarction and diabetes mellitus were studied. The mean serum cholesterol levels were higher in the indian group. This preliminary study suggests a negative correlation between leucocyte ascorbic acid and serum cholesterol levels in Indians, especially in patients with infarction. This, however, does not preclude an effect of latent ascorbic acid deficiency on the vessel wall. The possible relevance of the findings to the development of atherosclerosis is discussed.

Topics: Adult; Age Factors; Ascorbic Acid; Black or African American; Black People; Cholesterol; Coronary Disease; Diabetes Complications; Diabetes Mellitus; Humans; India; Leukocytes; Middle Aged; Myocardial Infarction; South Africa

Topics: Animals; Ascorbic Acid; Dehydroascorbic Acid; Diabetes Mellitus; Humans

It has been suggested earlier that the local deficiency of ascorbic acid in tissues could be responsible for development of various angiopathies in diabetes. Hyperglycemia is one of the factors which could contribute considerably to the development of local ascorbic acid deficiency. Therefore, the effect of glucose on uptake of L-[1-14C] ascorbic acid by fibroblasts was studied in vitro. The data clearly show that ascorbic acid uptake is inhibited instantly by glucose in a concentration dependent fashion. The results support the contention that local ascorbic acid deficiency in tissues could be a natural consequence of hyperglycemia of whatever cause. The rate of ascorbic acid uptake under various conditions suggests that additional supplements of ascorbic acid might be helpful to individuals in averting deleterious effects of hyperglycemia on tissue ascorbic acid supply.

Topics: Animals; Ascorbic Acid; Biological Transport; Cells, Cultured; Diabetes Mellitus; Fibroblasts; Glucose; Humans; Hyperglycemia; Mice; Skin

High but well-tolerated doses of the nutritional antioxidants selenium and vitamins E and C have significant immunostimulant, anti-inflammatory, and anti-carcinogenic effects which are well documented in the existing biomedical literature. In addition, these antioxidants help to protect the structural integrity of ischemic or hypoxic tissues, and may have useful anti-thrombotic actions as well. Supplementation with high-dose nutritional antioxidants may eventually gain a broad role in the prevention, treatment, or palliation of cancer, cardiovascular disease, infection, inflammatory disorders, and certain diabetic complications.

Topics: Adjuvants, Immunologic; Animals; Anti-Inflammatory Agents; Antioxidants; Arthritis; Ascorbic Acid; Cardiovascular Diseases; Diabetes Mellitus; Free Radicals; Humans; Hypoxia; Ischemia; Mice; Neoplasms; Rabbits; Rats; Selenium; Superoxides; Thrombosis; Vitamin E

Available evidence--some well-documented, some only preliminary--suggests that properly-designed nutritional insurance supplementation may have particular value in diabetes. Comprehensive micronutrient supplementation providing ample doses of antioxidants, yeast-chromium, magnesium, zinc, pyridoxine, gamma-linolenic acid, and carnitine, may aid glucose tolerance, stimulate immune defenses, and promote wound healing, while reducing the risk and severity of some of the secondary complications of diabetes.

Topics: Animals; Antioxidants; Ascorbic Acid; Calcium; Carnitine; Chromium; Diabetes Mellitus; gamma-Linolenic Acid; Humans; Linolenic Acids; Magnesium; Pyridoxine; Selenium; Thioctic Acid; Ubiquinone; Vitamin E; Zinc

Recent reports of high dehydroascorbic acid levels in Asian subjects suffering from diabetes mellitus have led us to examine plasma dehydroascorbic acid levels in diabetic and non-diabetic Europeans. We can find no evidence that diabetic patients have higher plasma dehydroascorbic acid levels than nondiabetics, and consider some possible reasons for the discrepancy between this finding and those of earlier reports.

Topics: Adolescent; Adult; Ascorbic Acid; Blood Glucose; Dehydroascorbic Acid; Diabetes Mellitus; Female; Humans; Male; Middle Aged

We report a girl aged 31/2 years in whom signs and symptoms of diabetes mellitus were falsified by the mother. Evaluation in hospital rapidly ruled out diabetes mellitus and the use of ascorbic acid as a marker enabled us to prove urine substitution by the girl's mother.

Topics: Ascorbic Acid; Child, Preschool; Diabetes Mellitus; Female; Glycosuria; Humans; Mother-Child Relations; Munchausen Syndrome

Rates of dehydroascorbate uptake by blood granulocytes and mononuclear cells are slower, and plasma ascorbate concentrations are lower, among persons with diabetes mellitus than in nondiabetic subjects. These measurements do not correlate with one another or with simultaneously measured plasma glucose or glycosylated hemoglobin; they do not differ with type of diabetes or mode of treatment. In those diabetic granulocytes that exhibit slow dehydroascorbate uptake, maximal velocity (Vmax) transport rates for dehydroascorbate, 2-deoxyglucose, and 3-O-methylglucose are decreased, each to the same degree, while Km values for transport of these ligands are not different from those observed in nondiabetic cells. Since diffusion of these ligands is facilitated by a common transporter, these observations may reflect decreased numbers of glucose transporters in the plasma membranes of some diabetic leukocytes.

Topics: 3-O-Methylglucose; Adult; Aged; Ascorbic Acid; Biological Transport; Blood Cells; Dehydroascorbic Acid; Deoxyglucose; Diabetes Mellitus; Female; Granulocytes; Humans; Leukocytes; Male; Methylglucosides; Middle Aged; Monocytes; Neutrophils

Topics: Animals; Ascorbic Acid; Ascorbic Acid Deficiency; Diabetes Mellitus; Glucose; Guinea Pigs; Humans; Lipid Metabolism; Rats

Diabur-test 5000, a new test strip for estimation of urinary glucose, was compared with the hexokinase glucose-6-phosphate dehydrogenase method in more than 2500 urine samples. By combination of two test ranges glucose concentrations of up to 5% can be detected by the strip test. After a reading time of 2 minutes, very precise estimation of urinary glucose is possible in eight steps from negative to 5%. False estimations of more than one color step virtually do not occur. Ketone bodies, salicylic acid and several antibiotics do not influence the test strip. Ascorbic acid shows a slight influence only in concentrations above 40 mg/dl. This influence disappears with glucose concentrations of more than 0.5%. Good correlation with the reference method, wide range of readings and simple handling make the test strip suited for the laboratory and particularly for self control of diabetic patients.

Topics: Anti-Bacterial Agents; Ascorbic Acid; Diabetes Mellitus; Glycosuria; Humans; Indicators and Reagents; Ketone Bodies; Reagent Strips; Salicylates

Ascorbic acid and dehydroascorbic acid were estimated in the blood of normal healthy subjects and diabetic patients. In normal subjects, blood contained only ascorbic acid while dehydroascorbic acid was practically absent. The ascorbic acid level was low in the blood of diabetic patients but the dehydroascorbic acid content was remarkably high, irrespective of age, sex, history of diabetes, or treatment. About 75% of blood dehydroascorbic acid was present in the erythrocytes: the rest was in plasma. High blood dehydroascorbic acid levels were also found in 90% of the non-diabetic offspring with both parents diabetic, in 24% of the non-diabetic offspring with one parent diabetic, and in 75% of the non-diabetic siblings of diabetic patients. It appears that, in persons having an hereditary predisposition to diabetes, high blood dehydroascorbic acid levels may be used as a marker for early detection of the disease.

Topics: Adolescent; Adult; Aged; Ascorbic Acid; Dehydroascorbic Acid; Diabetes Mellitus; Diabetes Mellitus, Type 1; Female; Humans; Male; Middle Aged

Topics: Animals; Ascorbic Acid; Blood Glucose; Diabetes Mellitus; Humans; Rats

Specialized "nutritional insurance" supplementation may reduce the risk of many important complications of long-term corticosteroid treatment. Supplementation with calcium, fluoride, activated vitamin D metabolites, and GTF, should help prevent osteoporosis. GTF, vitamin C, zinc and fluoride might help offset the inhibitory effect of corticosteroids on fibroblast and osteoblast function. Diabetic, hyperlipidemic and protein-losing effects might be compensated with supplementary GTF. Antioxidant nutrients could support humoral immunity and neutrophil function, while complementing the anti-inflammatory actions of corticosteroids. Supplementary magnesium could reduce the risk of nephrocalcinosis and nephrolithiasis.

Topics: Adrenal Cortex Hormones; Amino Acids; Ascorbic Acid; Chromium; Diabetes Mellitus; Double-Blind Method; Fluorides; Food, Fortified; Humans; Hydroxycholecalciferols; Hyperlipidemias; Immunologic Deficiency Syndromes; Nephrocalcinosis; Nicotinic Acids; Nutritional Requirements; Osteoporosis; Selenium; Silicon

An hypothesis is proposed relating the possible role of vitamin deficiency as an etiologic factor contributing to periodontal disease in diabetes. The hypothesis is based upon the following: (1) transport of ascorbate across cell membranes may be impaired by glucose, but facilitated by insulin; (2) glucose utilization is significantly accelerated by sublethal concentrations of endotoxin; (3) endotoxin-induced histamine sensitivity of tissue is enhanced by ascorbic deficiency; and (4) ascorbic acid deficiency alters mucosal barrier function. The interrelationship of these factors is discussed.

Topics: Ascorbic Acid; Ascorbic Acid Deficiency; Collagen; Diabetes Complications; Diabetes Mellitus; Endotoxins; Glucose; Histamine Release; Humans; Periodontal Diseases

In contrast to normal subjects diabetic patients and very low plasma ascorbic acid and significantly high (p less than 0.001) dehydroascorbic acid irrespective of age, sex, duration of the disease, type of treatment, and glycemic control. However, there was no significant difference between the mean leukocyte ascorbate concentrations of the two populations. The in vitro rates of dehydroascorbate reduction in the hemolysate and the erythrocyte reduced glutathione levels and the glucose-6-phosphate dehydrogenase activities, which regulate the dehydroascorbate reduction, were similar in normal and diabetic subjects. The turnover of ascorbic acid was higher in the diabetics than that in the normal volunteers. Experiments with diabetic rats indicated that the increased turnover of ascorbic acid was probably due to increased oxidation of ascorbate to dehydroascorbate in tissue mitochondria. Ascorbic acid supplementation at a dose of 500 mg per day for a brief period of 15 days resulted in an increase in the plasma ascorbate level temporarily, but it did not lower the blood glucose level of the diabetic patients.

Topics: Adolescent; Adult; Aged; Animals; Ascorbic Acid; Blood Glucose; Dehydroascorbic Acid; Diabetes Mellitus; Diabetes Mellitus, Experimental; Erythrocytes; Female; Glutathione Reductase; Humans; Male; Middle Aged; Mitochondria; Oxidation-Reduction; Rats

Topics: Ascorbic Acid; Avitaminosis; Clinical Enzyme Tests; Diabetes Mellitus; Female; Gastrointestinal Diseases; Hospitalization; Humans; Liver Diseases; Male; Pyridoxine; Riboflavin; Thiamine; Vitamins

Topics: Ascorbic Acid; Blood Glucose; Cholesterol; Diabetes Mellitus; Glucose Tolerance Test; Humans; Lipids; Phospholipids; Triglycerides

A new testing set for diluting urine allows to determine glucose in urine with the Diabur-test strip up to a concentration of 8.0 g/dl. The dilution by means of a pipette is absolutel;y practicable at a distinguished precision; the results show an excellent correlatiopn with the quantitative hexokinase method. Of all possible interfering substances tested only ascorbic acid influenced the reaction which, however, interfered only when minor glucosuria was present.

Topics: Ascorbic Acid; Diabetes Mellitus; Glycosuria; Humans; Reagent Kits, Diagnostic

Topics: Arachidonic Acids; Ascorbic Acid; Blood Platelets; Cyclic AMP; Diabetes Mellitus; Humans; Insulin; Male; Platelet Aggregation; Prostaglandins; Tongue

Topics: Ascorbic Acid; Chromatography, Thin Layer; Dehydroascorbic Acid; Diabetes Mellitus; Humans; Reference Values; Spectrophotometry

In 19 insulin-dependent diabetics under compensated metabolic conditions the influence of a highly-dosed short-term vitamin C-treatment with 2,000 mg of ascorbic acid on the carbohydrate and fat metabolism was examined during a stay in hospital. Under the treatment with vitamin C low concentrations of blood glucose in the daily profile are observed, in which case this effect of ascorbic acid on the carbohydrate metabolism cannot be statistically ascertained. Triglyceride, cholesterol, FFA-concentrations and glycerol concentrations are not influenced.

Topics: Ascorbic Acid; Carbohydrate Metabolism; Diabetes Mellitus; Dose-Response Relationship, Drug; Humans; Lipid Metabolism

A study was conducted to determine if high doses of ascorbic acid would affect the two-drop Clinitest determination for glucosuria in normal individuals. Numerous secondary literature sources indicate that large doses of ascorbic acid may cause a false positive Clinitest result. Three-gram and nine-gram doses of ascorbic acid following two dosing schedules (once daily and three times daily) were taken by nine normal individuals to determine if the renal excretion of large enough quantities of ascorbic acid or its metabolites would produce false positive results with the two-drop Clinitest procedure. Each dose was given for seven days in each schedule. There were only two (0.27%) trace positive Clinitest determinations reported out of 748 Clinitest determinations. High doses of ascorbic acid in normal individuals do not appear to affect the two-drop Clinitest determination for urinary glucose. The study indicates a need to be cautious about secondary literature references on drug-laboratory test interferences.

Topics: Ascorbic Acid; Copper; Diabetes Mellitus; False Positive Reactions; Glycosuria; Humans; Reagent Kits, Diagnostic; Sulfates

The recent popularization of self-prescribed large doses of vitamin C has increased the possibility for erroneous conclusions to be drawn from standard clinical methods used in urinary glucose monitoring, due to interference with these methods by the greatly elevated excretion of vitamin C. The coupled-enzyme-chromogen strip tests showed erroneously negative glucose levels in urines of both a diabetic individual and a subject with a genetic low renal threshold for glucose when they were supplementing their normal diets with 1-2 g vitamin C per day. With this regimen, their urinary vitamin C levels reached 200 mg/dl (11.4 mmol/l). For normal urine with vitamin C added, false-positive tests for glucose were found using Benedict's reagent when vitamin C was present at 250 mg/dl (14.3 mmol/l) or higher concentrations. In diabetic individuals consuming large quantities of vitamin C, this interference with standard coupled-enzyme-chromogen strip tests or Benedict's test could present a significant problem in diagnosis and clinical management of the disease. A simple anion exchange method of treating the urine was used to correct the false results.

Topics: Adult; Ascorbic Acid; Diabetes Mellitus; False Negative Reactions; False Positive Reactions; Glycosuria; Humans; Male; Urine

Topics: Adult; Aged; Ascorbic Acid; Diabetes Mellitus; Humans; Middle Aged

Glucose consumption was measured in the red cells of 15 diabetic patients and 13 normal subjects. The red cells were incubated in autologous serum with the glucose concentration adjusted to approximately 500 mg per 100 ml. Mean glucose consumption, both total and via the pentose phosphate pathway, by the red cells of the diabetic patients was not significantly different from that by the red cells of the normal subjects. Stimulation of the pentose phosphate pathway with ascorbate or methylene blue similarly revealed no difference between the two groups. Exposure of the red cells to ethanol in the incubation medium had no discernible effect on total glucose consumption but caused a decrease in glucose consumption by the pentose phosphate pathway. An effect of ethanol on glucose consumption by the pentose phosphate pathway was not evident in the presence of ascorbate or methylene blue. No difference in response to ethanol by the red cells of the diabetic patients and normal subjects was observed.

Topics: Adult; Ascorbic Acid; Blood Glucose; Diabetes Mellitus; Erythrocytes; Ethanol; Female; Humans; In Vitro Techniques; Male; Metabolic Clearance Rate; Methylene Blue

Topics: 2,3-Diketogulonic Acid; Ascorbic Acid; Colorimetry; Dehydroascorbic Acid; Diabetes Mellitus; Female; Homocysteine; Humans; Light; Male; Methylene Blue; Nitro Compounds; Phenylhydrazines; Sugar Acids

Topics: Amniotic Fluid; Ascorbic Acid; Asphyxia Neonatorum; Blood; Blood Group Incompatibility; Diabetes Mellitus; Female; Humans; Infant, Newborn; Injections, Intravenous; Labor, Obstetric; Maternal-Fetal Exchange; Placenta Diseases; Pregnancy; Pregnancy Complications; Pyelonephritis; Rh-Hr Blood-Group System; Umbilical Cord

Topics: Adult; Ascorbic Acid; Blood Glucose; Brachial Artery; Diabetes Mellitus; Fasting; Female; Forearm; Glucose; Humans; Injections, Intra-Arterial; Insulin; Leukocytes; Male; Middle Aged; Subclavian Vein

Topics: Ascorbic Acid; Carcinoid Tumor; Chromatography, Thin Layer; Clinical Enzyme Tests; Diabetes Mellitus; Diagnostic Errors; Diuresis; False Negative Reactions; False Positive Reactions; Gentisates; Glycosuria; Humans; Methods; Osmolar Concentration; Reagent Strips

Topics: Alloxan; Anti-Bacterial Agents; Ascorbic Acid; Diabetes Mellitus; Diazoxide; Disaccharides; Epinephrine; Female; Glucagon; Glucocorticoids; Glucose; Growth Hormone; Heptoses; Hormones; Humans; Insulin; Insulin Antagonists; Insulin Secretion; Ketones; Langerhans Cells; Male; Mannose; Pancreas; Thyroxine; Uric Acid

Topics: Animals; Ascorbic Acid; Diabetes Mellitus; Fertility; Glycoproteins; Male; Pancreatectomy; Rats; Testicular Diseases; Testis

Topics: Adult; Ascorbic Acid; Blood Glucose; Cholesterol; Diabetes Complications; Diabetes Mellitus; Diencephalon; Female; Goiter; Humans; Hypothyroidism; Influenza, Human; Magnesium Sulfate; Movement Disorders; Penicillins; Streptomycin; Thiamine

Topics: Animals; Ascorbic Acid; Chickens; Diabetes Mellitus; False Positive Reactions; Female; Fetal Death; Fetus; Glycosuria; Guinea Pigs; Humans; Oxalates; Phosphates; Pregnancy; Rats; Urinary Calculi

Topics: Ascorbic Acid; Diabetes Mellitus; Glucose Tolerance Test; Humans

Topics: Ascorbic Acid; Aspirin; Asthma; Calcium; Citrates; Coronary Disease; Depression, Chemical; Diabetes Mellitus; Duodenal Ulcer; Dwarfism, Pituitary; Emphysema; Facial Paralysis; Gluconates; Histamine H1 Antagonists; Humans; Hypertension; Hyperthyroidism; Kidney Calculi; Liver Diseases, Parasitic; Magnesium; Oxalates; Phosphates; Pyridoxine; Schistosomiasis; Stimulation, Chemical; Terpenes; Tuberculosis, Pulmonary

Topics: Alloxan; Ascorbic Acid; Diabetes Mellitus; Fatty Acids; Humans; In Vitro Techniques

Topics: Adipose Tissue; Alcohol Oxidoreductases; Animals; Aorta; Arteries; Ascorbic Acid; Carbon Dioxide; Carbon Isotopes; Chromatography, Paper; Decarboxylation; Diabetes Mellitus; Diabetes Mellitus, Experimental; Diabetic Angiopathies; Femoral Artery; Glucose; Glucuronates; Guinea Pigs; Humans; Male; Oxidoreductases; Rats; Rats, Inbred Strains; Species Specificity; Xylitol

Topics: Adolescent; Adult; Aged; Ascorbic Acid; Diabetes Mellitus; Female; Humans; Male; Middle Aged; ortho-Aminobenzoates; Phenformin; Vitamin B Complex

Topics: Animals; Ascorbic Acid; Blood Glucose; Diabetes Mellitus; Female; Guinea Pigs; Male; Quinolines; Sodium Chloride; Sulfates; Sulfonic Acids; Zinc

Topics: Ascorbic Acid; Autoanalysis; Blood Glucose; Diabetes Mellitus; Glucose Oxidase; Humans; Indicators and Reagents; Methods; Time Factors; Uric Acid

Topics: Animals; Ascorbic Acid; Blood Glucose; Diabetes Mellitus; Insulin; Rats

Topics: Adult; Aged; Ascorbic Acid; Calcium; Carbohydrate Metabolism; Diabetes Mellitus; Female; Humans; Male; Middle Aged; Niacinamide; Pantothenic Acid; Vitamin B Complex

Topics: Ascorbic Acid; Blood Glucose; Carbohydrate Metabolism; Diabetes Mellitus; Glucose Tolerance Test; Humans

Topics: Ascorbic Acid; Blood Glucose; Diabetes Mellitus; Glycerol; Humans; Mannitol

Topics: Ascorbic Acid; Blood Chemical Analysis; Diabetes Mellitus; Geriatrics; Humans; Tolbutamide

Topics: Ascorbic Acid; Dehydroascorbic Acid; Diabetes Mellitus; Vitamins

Topics: Aged; Aged, 80 and over; Ascorbic Acid; Diabetes Mellitus; Vitamin A; Vitamin B Complex; Vitamins

Topics: Adolescent; Ascorbic Acid; Carbohydrate Metabolism; Child; Dental Caries; Diabetes Mellitus; Humans; Insulin; Vitamins

Topics: Aged; Aged, 80 and over; Ascorbic Acid; Biological Transport; Diabetes Mellitus; Humans; Vitamins

Topics: 4-Aminobenzoic Acid; Ascorbic Acid; Benzoic Acid; Diabetes Mellitus; Female; Humans; Parity; Salicylic Acid; Vitamins

Topics: Adolescent; Ascorbic Acid; Carbohydrate Metabolism; Child; Dental Caries; Diabetes Mellitus; Humans; Insulin; Vitamins

Topics: Ascorbic Acid; Diabetes Mellitus; Folic Acid; Glycerophosphates; Humans; Vitamin B Complex; Vitamin E; Vitamins

Topics: Arthritis; Arthritis, Rheumatoid; Ascorbic Acid; Desoxycorticosterone; Desoxycorticosterone Acetate; Diabetes Mellitus; Vitamins

Topics: Ascorbic Acid; Cataract; Dehydroascorbic Acid; Diabetes Mellitus; Humans; Vitamins

Topics: Arthritis; Arthritis, Rheumatoid; Ascorbic Acid; Desoxycorticosterone; Diabetes Mellitus; Humans; Vitamins

Topics: Alloxan; Anemia; Animals; Ascorbic Acid; Diabetes Mellitus; Spiders; Tracheophyta; Vitamins

Topics: Animals; Ascorbic Acid; Diabetes Mellitus; Diabetes Mellitus, Experimental; Humans; Vitamins

Topics: Animals; Ascorbic Acid; Diabetes Mellitus; Diabetes Mellitus, Experimental; Humans; Vitamins

Topics: Ascorbic Acid; Dehydroascorbic Acid; Diabetes Mellitus; Humans

Topics: Animals; Ascorbic Acid; Diabetes Mellitus; Diabetes Mellitus, Experimental; Species Specificity; Vitamins

Topics: Ascorbic Acid; Diabetes Complications; Diabetes Mellitus; Gangrene; Histidine; Humans