[199][200][201], There is conflicting evidence about the benefits of interventions with vitamin D,[202] one view purporting an intake of 4,000–12,000 IU/day from sun exposure with concomitant serum 25-hydroxyvitamin D levels of 40 to 80 ng/mL,[203] while another view is that serum concentrations above 50 ng/mL are not plausible. In addition, for products intended for infants, the FDA recommends the dropper hold no more than 400 IU. b. a tonality having D as the tonic. [2], The major natural source of the vitamin is synthesis of cholecalciferol in the lower layers of skin epidermis through a chemical reaction that is dependent on sun exposure (specifically UVB radiation). [35][36] Nutritional rickets exists in countries with intense year-round sunlight such as Nigeria and can occur without vitamin D deficiency. [177], In birds and fur-bearing mammals, fur or feathers block UV rays from reaching the skin. The letter d is used in the alphabets of many languages, and in several romanization systems of non-Latin scripts to represent the voiced alveolar or dental plosive ( /d/ ). One thousand micrograms per day in infants has produced toxicity within one month. the fourth letter of the English alphabet, a consonant. The conversion of previtamin D3 to vitamin D3 in the skin is about 10 times faster than in an organic solvent. [197], In 1969, after studying nuclear fragments of intestinal cells, a specific binding protein for vitamin D called the vitamin D receptor was identified by Mark Haussler and Tony Norman. [140][141], While some studies have found that vitamin D3 raises 25(OH)D blood levels faster and remains active in the body longer,[142][143] others contend that vitamin D2 sources are equally bioavailable and effective as D3 for raising and sustaining 25(OH)D.[130][144][145], Vitamin D content in typical foods is reduced variably by cooking. [2][5][6] Only a few foods, such as the flesh of fatty fish, naturally contain significant amounts of vitamin D.[7][8] In the U.S. and other countries, cow's milk and plant-derived milk substitutes are fortified with vitamin D, as are many breakfast cereals. [77] It is unclear, however, if taking additional vitamin D in the diet or as supplements affects the risk of cancer. [163], Vitamin D overdose causes hypercalcemia, which is a strong indication of vitamin D toxicity – this can be noted with an increase in urination and thirst. These may be followed by polyuria, polydipsia, weakness, insomnia, nervousness, pruritus and ultimately kidney failure. [16], Another 2014 review concluded that vitamin D3 may decrease the risk of death from cancer (one fewer death in 150 people treated over 5 years), but concerns with the quality of the data were noted. [64][65][66] The relationship between serum calcifediol level and all-cause mortality is parabolic. [18] The binding of calcitriol to the VDR allows the VDR to act as a transcription factor that modulates the gene expression of transport proteins (such as TRPV6 and calbindin), which are involved in calcium absorption in the intestine. 8: Vitamin D Binding Protein", "Age-old children's disease back in force", "Vitamin A, Vitamin D, Cartilage, Bones, and Teeth", "Chromosomal receptor for a vitamin D metabolite", "Identification of 1,25-dihydroxycholecalciferol, a form of vitamin D3 metabolically active in the intestine", "Vitamin D in Autoimmunity: Molecular Mechanisms and Therapeutic Potential", "Office of Dietary Supplements - Vitamin D", "Effects of Nutritional Supplements and Dietary Interventions on Cardiovascular Outcomes: An Umbrella Review and Evidence Map", "Advisory statement on likely place in therapy | COVID-19 rapid evidence summary: vitamin D for COVID-19 | Advice | NICE", "Exploring links between vitamin D deficiency and COVID-19", "Vitamin D receptor stimulation to reduce acute respiratory distress syndrome (ARDS) in patients with coronavirus SARS-CoV-2 infections: Revised Ms SBMB 2020_166", "International clinical trials assessing vitamin D in people with COVID-19", NIH Vitamin D Fact Sheet for Health Professionals, Calcitriol (1,25-dihydroxycholecalciferol), https://en.wikipedia.org/w/index.php?title=Vitamin_D&oldid=982899792, Short description is different from Wikidata, All Wikipedia articles written in American English, Articles with limited geographic scope from February 2019, Articles containing potentially dated statements from November 2010, All articles containing potentially dated statements, Wikipedia articles with SUDOC identifiers, Creative Commons Attribution-ShareAlike License, IUPAC name: (1S,3Z)-3-[(2E)-2-[(1R,3aS,7aR)-7a-methyl-1-[(2R)-6-methylheptan-2-yl]-2,3,3a,5,6,7-hexahydro-1H-inden-4-ylidene]ethylidene]-4-methylidenecyclohexan-1-ol, * Adequate intake, no RDA/RDI yet established, reduced risk of falling in people over age 60, "Adequate calcium and vitamin D, as part of a well balanced diet, along with physical activity, may reduce the risk of osteoporosis. VDR activation in the intestine, bone, kidney, and parathyroid gland cells leads to the maintenance of calcium and phosphorus levels in the blood (with the assistance of parathyroid hormone and calcitonin) and to the maintenance of bone content. [59], A United States Institute of Medicine (IOM) report states: "Outcomes related to cancer, cardiovascular disease and hypertension, and diabetes and metabolic syndrome, falls and physical performance, immune functioning and autoimmune disorders, infections, neuropsychological functioning, and preeclampsia could not be linked reliably with calcium or vitamin D intake and were often conflicting. By the expiration of his patent in 1945, rickets had been all but eliminated in the US. [1], One of the most important roles of vitamin D is to maintain skeletal calcium balance by promoting calcium absorption in the intestines, promoting bone resorption by increasing osteoclast number, maintaining calcium and phosphate levels for bone formation, and allowing proper functioning of parathyroid hormone to maintain serum calcium levels. [16][60] Low vitamin D levels may result from disease rather than cause disease. [25] A diet with insufficient vitamin D in conjunction with inadequate sun exposure causes vitamin D deficiency. Second, previtamin D3 spontaneously isomerizes to vitamin D3 (cholecalciferol) in an antarafacial sigmatropic [1,7] hydride shift. [16] Its general use for prevention of this disease in those without vitamin D deficiency is thus likely not needed. Vitamin D deficiency can result in lower bone mineral density and an increased risk of reduced bone density (osteoporosis) or bone fracture because a lack of vitamin D alters mineral metabolism in the body. American researchers Elmer McCollum and Marguerite Davis in 1914[12] discovered a substance in cod liver oil which later was called "vitamin A". Circulating calcifediol may then be converted into calcitriol, the biologically active form of vitamin D, in the kidneys. 7-Dehydrocholesterol reacts with UVB light at wavelengths of 290–315 nm. [126] The European Menopause and Andropause Society recommends postmenopausal women consume 15 µg (600 IU) until age 70, and 20 µg (800 IU) from age 71. A meeting took place with J.B.S. [125], Non-government organisations in Europe have made their own recommendations. 3. a. the second note of the ascending C major scale. [2] Although the effects of osteomalacia are thought to contribute to chronic musculoskeletal pain,[50] there is no persuasive evidence of lower vitamin D levels in chronic pain sufferers[51] or that supplementation alleviates chronic nonspecific musculoskeletal pain. Vitamin D also affects the immune system, and VDRs are expressed in several white blood cells, including monocytes and activated T and B cells. ", Adequate calcium and regular exercise may help to achieve strong bones in children and adolescents and may reduce the risk of osteoporosis in older adults. Vitamin D is a group of fat-soluble secosteroids responsible for increasing intestinal absorption of calcium, magnesium, and phosphate, and multiple other biological effects. By binding to vitamin D-binding protein, calcitriol is transported throughout the body, including to the classical target organs of intestine, kidney and bone. Health Canada published recommended dietary allowances (RDA) and tolerable upper intake levels for vitamin D in 2012[114] based on the Institute of Medicine report. For all people over the age of 1, including women who are pregnant or lactating, they set an adequate intake of 15 μg/day (600 IU).[116]. Manufactured foods fortified with vitamin D include some fruit juices and fruit juice drinks, meal replacement energy bars, soy protein-based beverages, certain cheese and cheese products, flour products, infant formulas, many breakfast cereals, and milk.