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7-Dehydrocholesterol (7-DHC) is a zoosterol that functions in the serum as a cholesterol precursor, and is photochemically converted to vitamin D 3 in the skin, therefore functioning as provitamin-D 3. The presence of this compound in human skin enables humans to manufacture vitamin D 3 (cholecalciferol).
Biotin (also known as vitamin B 7 or vitamin H) is one of the B vitamins. [ 1 ] [ 2 ] [ 3 ] It is involved in a wide range of metabolic processes, both in humans and in other organisms, primarily related to the utilization of fats, carbohydrates, and amino acids. [ 4 ]
Quizlet was founded in October 2005 by Andrew Sutherland, who at the time was a 15-year old student, [2] and released to the public in January 2007. [3] Quizlet's primary products include digital flash cards, matching games, practice electronic assessments, and live quizzes. In 2017, 1 in 2 high school students used Quizlet. [4]
Riboflavin, also known as vitamin B 2, is a water-soluble vitamin and is one of the B vitamins. [3] [4] [5] Unlike folate and vitamin B 6, which occur in several chemically related forms known as vitamers, riboflavin is only one chemical compound.
Within the epidermal layer of skin, 7-dehydrocholesterol undergoes an electrocyclic reaction as a result of UVB light at wavelengths between 290 and 310 nm, with peak synthesis occurring at 293 nm. [42] This results in the opening of the vitamin precursor B-ring through a conrotatory pathway making previtamin D 3 (pre-cholecalciferol). [43]
As interpreted by the Linus Pauling Institute, dietary polyphenols have little or no direct antioxidant food value following digestion. [7] Not like controlled test tube conditions, the fate of flavones or polyphenols in vivo shows they are poorly absorbed and poorly conserved (less than 5%), so that most of what is absorbed exists as ...
Vitamin B 12 deficiency is preventable with supplements, which are recommended for pregnant vegetarians and vegans, and not harmful in others. [2] Risk of toxicity due to vitamin B 12 is low. [2] Vitamin B 12 deficiency in the US and the UK is estimated to occur in about 6 percent of those under the age of 60, and 20 percent of those over the ...
Vitamin D 3 (cholecalciferol) is produced industrially by exposing 7-dehydrocholesterol to UVB and UVC light, followed by purification. The 7-dehydrocholesterol is sourced as an extraction from lanolin, a waxy skin secretion in sheep's wool. [189] Vitamin D 2 (ergocalciferol) is produced in a similar way using ergosterol from yeast as a ...