Which is the only vitamin that the human body can synthesize?
Vitamin D D produced is degraded. Synthesis of vitamin D in nature is dependent on the presence of UV radiation and subsequent activation in liver and in kidney. Many animals synthesize vitamin D from 7-dehydrocholesterol, and many fungi synthesize vitamin D from ergosterol. Click on icon in lower right corner to open. The transformation that converts 7-dehydrocholesterol to vitamin D occurs in two steps. First, 7-dehydrocholesterol is photolyzed by ultraviolet light in a 6-electron conrotatory ring-opening electrocyclic reaction; the product is previtamin D. Second, previtamin D spontaneously isomerizes to vitamin D (cholecalciferol) in an antarafacial sigmatropic [1,7] hydride shift. At room temperature,
Vitamin C the red blood cells have evolved a mechanism to more efficiently utilize the vitamin C present in the body by recycling oxidized -dehydroascorbic acid (DHA) back into ascorbic acid for reuse by the body. The mechanism was not found to be present in mammals that synthesize their own vitamin C. Vitamin C megadosage is a term describing the consumption or injection of vitamin C in doses comparable to or higher than the amounts produced by the livers of mammals which are able to synthesize vitamin C. The theory behind this, although not the actual term, was described in 1970 in