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Unlike the other twelve vitamins, vitamin D is only conditionally essential - in a preindustrial society people had adequate exposure to sunlight and the vitamin was a hormone, as the primary natural source of vitamin D was the synthesis of cholecalciferol in the lower layers of the skin’s epidermis, triggered by a photochemical reaction with ...
There are not many foods that naturally have vitamin D. [33] Examples are cod liver oil and oily fish. If people cannot get sunlight, then they will need 1,000 IU of vitamin D per day to stay healthy. [34] A person would have to eat oily fish three or four times per week in order to get enough vitamin D from that food source alone.
Mapping of several bone diseases onto levels of vitamin D (calcidiol) in the blood [6] Normal bone vs. osteoporosis. Vitamin D deficiency is typically diagnosed by measuring the concentration of the 25-hydroxyvitamin D in the blood, which is the most accurate measure of stores of vitamin D in the body.
Humans need some UV radiation to maintain adequate vitamin D levels. According to the World Health Organization: [49] There is no doubt that a little sunlight is good for you! But 5–15 minutes of casual sun exposure of hands, face and arms two to three times a week during the summer months is sufficient to keep your vitamin D levels high.
The ultraviolet radiation in sunlight has both positive and negative health effects, as it is both a principal source of vitamin D 3 and a mutagen. [48] A dietary supplement can supply vitamin D without this mutagenic effect, [ 49 ] but bypasses natural mechanisms that would prevent overdoses of vitamin D generated internally from sunlight.
The three vitamin precursors used in these salvage metabolic pathways are nicotinic acid (NA), nicotinamide (Nam) and nicotinamide riboside (NR). [6] These compounds can be taken up from the diet and are termed vitamin B 3 or niacin. However, these compounds are also produced within cells and by digestion of cellular NAD +.
Vitamin A plays an essential role in developing the immune system in children, therefore, it is considered an essential micronutrient that can greatly affect health. [2] However, because of the expense of testing for deficiencies, many developing nations have not been able to fully detect and address vitamin A deficiency, leaving vitamin A ...
Upon exposure to ultraviolet UV-B rays in the sun light, 7-DHC is converted into vitamin D 3 via previtamin D 3 as an intermediate isomer. It is also found in the milk of several mammalian species. [ 1 ] [ 2 ] Lanolin , a waxy substance that is naturally secreted by wool-bearing mammals, contains 7-DHC which is converted into vitamin D by ...