ascorbic-acid and Sarcopenia

In patients with chronic kidney disease, skeletal muscle dysfunction is associated with mortality. Uremic sarcopenia is caused by ageing, malnutrition, and chronic inflammation, but the molecular mechanism and potential therapeutics have not been fully elucidated yet. We hypothesize that accumulated uremic toxins might exert a direct deteriorative effect on skeletal muscle and explore the pharmacological treatment in experimental animal and culture cell models. The mice intraperitoneally injected with indoxyl sulfate (IS) after unilateral nephrectomy displayed an elevation of IS concentration in skeletal muscle and a reduction of instantaneous muscle strength, along with the predominant loss of fast-twitch myofibers and intramuscular reactive oxygen species (ROS) generation. The addition of IS in the culture media decreased the size of fully differentiated mouse C2C12 myotubes as well. ROS accumulation and mitochondrial dysfunction were also noted. Next, the effect of the β2-adrenergic receptor (β2-AR) agonist, clenbuterol, was evaluated as a potential treatment for uremic sarcopenia. In mice injected with IS, clenbuterol treatment increased the muscle mass and restored the tissue ROS level but failed to improve muscle weakness. In C2C12 myotubes stimulated with IS, although β2-AR activation also attenuated myotube size reduction and ROS accumulation as did other anti-oxidant reagents, it failed to augment the mitochondrial membrane potential. In conclusion, IS provokes muscular strength loss (uremic dynapenia), ROS generation, and mitochondrial impairment. Although the β2-AR agonist can increase the muscular mass with ROS reduction, development of therapeutic interventions for restoring skeletal muscle function is still awaited.

Topics: Adrenergic beta-2 Receptor Agonists; Animals; Ascorbic Acid; Cell Size; Clenbuterol; Female; Indican; Membrane Potential, Mitochondrial; Mice; Mice, Inbred C57BL; Mitochondria; Muscle Fibers, Skeletal; Muscle Proteins; Muscle Strength; Muscle, Skeletal; Muscular Atrophy; Oxidative Stress; Reactive Oxygen Species; Receptors, Adrenergic, beta-2; Sarcopenia; SKP Cullin F-Box Protein Ligases

The purpose of this study was to assess the association between fruit intake and abnormalities in body composition (bone, muscle, and adipose tissue) related to osteosarcopenic obesity (OSO) in postmenopausal women.. The data of 1420 postmenopausal women aged 50-64 years were collected from cross-sectional studies conducted by the Korea National Health and Nutrition Examination Survey (KNHANES) from 2008 to 2010.. A dietary intake survey was administered using the 24-h dietary recall method, and intakes of nutrients and food groups were analyzed. Body composition was evaluated using dual-energy x-ray absorptiometry (DEXA). Body composition abnormalities include low bone mass (T-score<-1.0), low muscle mass (weight-adjusted appendicular skeletal muscle mass below the mean reference value of healthy young adults), and obesity (waist circumference ≥85 cm). The associations between nutrient intake and fruit groups and the number of abnormalities in body composition were tested by logistic regression analysis.. The intakes of vitamin C and potassium per 1000 kcal of total energy intake were significantly lower in women with a larger number of abnormalities in body composition (p = 0.0155 and p = 0.0037, respectively). After controlling for covariates, women with a high intake of fruit (≥257.4 g/d) had a significantly reduced likelihood of multiple abnormalities in body composition compared with women with no fruit intake (p for trend: p < 0.01 for those with one, two, or three abnormalities).. Intake of fruits rich in vitamin C and potassium may help to decrease OSO-related risks in middle-aged postmenopausal women.

Topics: Absorptiometry, Photon; Ascorbic Acid; Body Composition; Body Weight; Bone Diseases, Metabolic; Cross-Sectional Studies; Diet; Energy Intake; Female; Fruit; Humans; Middle Aged; Nutrition Surveys; Obesity; Postmenopause; Republic of Korea; Sarcopenia; Vitamins; Waist Circumference

In this study, we examined the relationship between sarcopenic obesity (SO) and nutrition status, according to sex in Korean adults who were 60 years or older. Body composition was categorized as SO, sarcopenic nonobesity, nonsarcopenic obesity, and nonsarcopenic nonobesity. Obesity was defined by body mass index. Sarcopenia was defined as an appendicular skeletal muscle mass divided by weight (Wt) of less than 1 SD below the sex-specific mean for young adults. Subjects included 1433 subjects (658 men and 775 women) who were 60 years or older and who participated in the fifth Korea National Health and Nutritional Examination Survey 2010. Sarcopenic obesity was more prevalent in women (31.3%) than in men (19.6%). Individuals with SO had significantly higher fasting insulin, homeostasis model assessment of insulin resistance (male: 3.2 ± 1.4, female: 3.4 ± 2.1), and triglycerides (male: 167.3 ± 90.6 mg/dL, female: 160.7 ± 85.0 mg/dL). High-density lipoprotein was under the normal criteria (50 mg/dL) in women. Intake of nutrients associated with muscle loss (protein, vitamin D, calcium, and vitamin C) was significantly different among the male but not the female groups. Although protein intake was normal, calcium and vitamin D intakes were insufficient in all groups. In conclusion, body composition changes were related to nutrient intakes in elderly (60 years or older) men but not elderly women. Women had a higher prevalence of SO than did men, suggesting that early nutritional intervention in elderly women may help them address age-associated body composition changes.

Topics: Adult; Aged; Ascorbic Acid; Asian People; Body Composition; Body Mass Index; Body Weight; Calcium, Dietary; Cholesterol, HDL; Dietary Proteins; Energy Intake; Female; Healthy Volunteers; Humans; Insulin; Insulin Resistance; Male; Middle Aged; Muscle, Skeletal; Nutrition Surveys; Nutritional Status; Obesity; Prevalence; Republic of Korea; Risk Factors; Sarcopenia; Triglycerides; Vitamin D; Young Adult