vitamin-d-2 and Endocrine-System-Diseases

There is no doubt that vitamin D must be activated to the hormonal form 1,25-dihydroxyvitamin D to achieve full biological activity or that many tissues participate in this activation process-be it endocrine or autocrine. We believe that not only is 25-hydroxyvitamin D important to tissue delivery for this activation process, but also that intact vitamin D has a pivotal role in this process.. In this review, evidence on the vitamin D endocrine/autocrine system is presented and discussed in relation to vitamin D-binding protein affinity, circulating half-lives, and enzymatic transformations of vitamin D metabolites, and how these affect biological action in any given tissue.. Circulating vitamin D, the parent compound, likely plays an important physiological role with respect to the vitamin D endocrine/autocrine system, as a substrate in many tissues, not originally thought to be important. Based on emerging data from the laboratory, clinical trials, and data on circulating 25-hydroxyvitamin D amassed during many decades, it is likely that for the optimal functioning of these systems, significant vitamin D should be available on a daily basis to ensure stable circulating concentrations, implying that variation in vitamin D dosing schedules could have profound effects on the outcomes of clinical trials because of the short circulating half-life of intact vitamin D.

Topics: 25-Hydroxyvitamin D 2; Animals; Autocrine Communication; Calcifediol; Calcitriol; Dietary Supplements; Endocrine System; Endocrine System Diseases; Ergocalciferols; Humans; Vitamin D; Vitamin D Deficiency

Individuals are capable of producing vitamin D with proper exposure to sunlight. However, several factors can interfere with the effectiveness of this process. Most sunscreens filter out UVB light, thus inhibiting vitamin D production. Individuals with more darkly pigmented skin have greater difficulty producing vitamin D because melanin acts as an effective natural sunscreen, requiring longer sun exposure to produce an adequate daily allotment of vitamin D. Additionally, solely breastfed infants whose mothers suffered from vitamin D deficiency or insufficiency when pregnant have smaller reserves of the nutrient and are at greater risk of developing nutritional rickets. Vitamin D deficiency leads to rickets, osteomalacia, and osteoporosis. Long-term vitamin D insufficiency can lead to paracrine effects such as type 1 diabetes, cancer, and multiple sclerosis. This article reviews the current literature on vitamin D deficiency and insufficiency and their relation to different disease states. Potential areas for research are discussed.

Topics: Child, Preschool; Cholecalciferol; Endocrine System Diseases; Ergocalciferols; Female; Humans; Infant; Infant, Newborn; Nutritive Value; Paracrine Communication; Pregnancy; Vitamin D Deficiency

Topics: Adult; Age Factors; Anemia, Pernicious; Calcium; Candidiasis; Child; Dihydrotachysterol; Endocrine System Diseases; Ergocalciferols; Humans; Hypoparathyroidism; Infant, Newborn; Infant, Newborn, Diseases

Topics: Blood Glucose; Carcinoma, Hepatocellular; Diabetes Mellitus; Endocrine System Diseases; Ergocalciferols; Fatty Liver; Gastrointestinal Neoplasms; Gonadal Steroid Hormones; Gynecomastia; Hormones, Ectopic; Humans; Hyperinsulinism; Liver Diseases; Liver Neoplasms; Male; Renin-Angiotensin System; Thyroid Diseases