Vitamin Tidbit of the Day
Vitamin D is technically not a vitamin at all.
The generic term vitamin D designates a group of chemically related compounds that posess antirachitic activity. The two most prominent members of this group are vitamin D2 (ergocalcigerol) and vitamin D3 (cholecalciferol). Vitamin D2 is derived from a common plant steroid, ergosterol, and is the form that was employed for nutritional vitamin D fortification of foods from the 40's to 60's. Vitamin D3 is the form of vitmain D obtained when radiant energy from the sun strikes the skin and converts the precursor 7-dehydrocholesterol. Since the body is capable of producing vitamin D3, vitamin D does not meet the classical definition of a vitamin. A more accurate description of vitamin D is that it is a prohormone; thus, vitamin D is metabolized to a biologically active form that functions as a steroid hormone.
Handbook of Vitamins, 4th Edition, page 42
The body can only produce 10,000 i.u. of vitamin D in the first 30 minutes of sun exposure in optimal conditions. Amounts past the initial 30 minutes are drastically less. Factors such as skin tone and geographical location will determine the full extent of vitamin D production -- those of darker skin tone would need a proportionately longer period of time in the sun to produce the same amount of D3.
The generic term vitamin D designates a group of chemically related compounds that posess antirachitic activity. The two most prominent members of this group are vitamin D2 (ergocalcigerol) and vitamin D3 (cholecalciferol). Vitamin D2 is derived from a common plant steroid, ergosterol, and is the form that was employed for nutritional vitamin D fortification of foods from the 40's to 60's. Vitamin D3 is the form of vitmain D obtained when radiant energy from the sun strikes the skin and converts the precursor 7-dehydrocholesterol. Since the body is capable of producing vitamin D3, vitamin D does not meet the classical definition of a vitamin. A more accurate description of vitamin D is that it is a prohormone; thus, vitamin D is metabolized to a biologically active form that functions as a steroid hormone.
Handbook of Vitamins, 4th Edition, page 42
The body can only produce 10,000 i.u. of vitamin D in the first 30 minutes of sun exposure in optimal conditions. Amounts past the initial 30 minutes are drastically less. Factors such as skin tone and geographical location will determine the full extent of vitamin D production -- those of darker skin tone would need a proportionately longer period of time in the sun to produce the same amount of D3.
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