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Vitamin D. The Sunshine “Vitamin”. History . Vitamin D was discovered as a cure for Rickets in the early 20 th century. It was first understood to only come from the skin of animals and was necessary for the body, and therefore it was named a vitamin.
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Vitamin D The Sunshine “Vitamin”
History • Vitamin D was discovered as a cure for Rickets in the early 20th century. • It was first understood to only come from the skin of animals and was necessary for the body, and therefore it was named a vitamin. • However, further research showed that humans are able to manufacture significant quantities of it in their skin, this technically means that it is not a vitamin.
Rickets • A bone disease brought on by a Vitamin D deficiency. • Rickets causes weakening and softening of the bones in children. • It afflicted many children in the 18th and 19th century, killing many due to a lack of understanding of the disease. • The first cure for rickets came in the early 19th century in the form of cod liver oil; however, the reason why this worked was not know till the early 20th century.
Vitamin D • Vitamin D is a group of fat-soluble steroid molecules that are derived from the parent structure cholesterol. • Vitamin D is based on the cyclopentanoperhydrophenanthrene ring structure. • It is unique in that it is the only vitamin that is produced inside the body. • It is technically classified as a seco steroid hormone due to the fact that it is manufactured by the body and plays regulatory roles.
Vitamin D • There are two dominant forms of vitamin D, D2and D3. • Vitamin D, when either ingested or created in the skin, is inactive and must be hydroxylated two times in order to become hormonally active and useful to the body. • The first hydroxylation takes place in the liver where the number 25 carbon is hydroxylated. • The second hydroxylation takes place in the kidney where the number 1 carbon is hydroxylated.
Vitamin D3 • Also known as cholecalciferol. • Produced photochemically in the skin of animals and humans from the ultraviolet radiation of 7-dehydrocholesterol. • Regulation of production is controlled by an equilibrium; meaning that when the concentration of D3is high enough the ultraviolet radiation begins to break down the D3. 1,25- Dihydroxycholecalciferol 7-Dehydrocholesterol
Vitamin D3 • Vitamin D3 is produced in the epidermis of the skin. • The epidermis contains five strata. • From outer to inner: • Stratum Corneum • Stratum Lucidum • Stratum Granulosum • Stratum Spinosum • Stratum Basale • The stratum spinosum and basale is where the highest concentration of 7-dehydrocholesterol is found. • The melanin concentration in the epidermis is a factor that must be considered. UVB Melanin UVB 7-dehydrocholesterol
Vitamin D2 • Also known as ergocalciferol • Produced photochemically by the ultraviolet radiation of ergosterol in plants. • Functionally serves the same purpose as D3, however it is markedly less effective. 1,25- Dihydroxyergocalciferol Ergosterol
Comparison 1,25-Dihydroxycholecalciferol 1,25-Dihydroxyergocalciferol
Major Biological Role • Vitamin D is responsible for the regulation of calcium and phosphorus in the serum. • Vitamin D can increase or decrease the small intestine effectiveness of absorbing calcium and phosphorus. • This is made possible by the vitamin D receptor (VDR) which conformationally changes when bound to 1,25-dihydroxy vitamin D, which allows absorption of calcium and phosphorus in the small intestine so that bone mineralization can occur.
Minor/Recently Discovered biological roles • Recent studies have shown that vitamin D may be able to suppress some autoimmune diseases. • Also a recent study showed that vitamin D plays some role in neurotransmitter synthesis, however the exact role is not known yet.
Daily intake Still being debated…
Conclusion • Vitamin D is absolutely essential for natural function of the body. • We still do not understand all of the uses of vitamin D in the body and therefore further research must be conducted.
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