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Vitamin D
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Vitamin D is not abundant in our usual food choices, so we get most of the vitamin from sun exposure and multivitamins. The problem is that the sun is not a reliable source for everyone.[4] Vitamin D is important for calcium homeostasis and for optimal skeletal health. Vitamin D-2, also known as ergocalciferol, is obtained from irradiated fungi such as yeast.[5] Vitamin D is also used to treat these conditions. [6] Vitamin D is found in numerous dietary sources such as fish, eggs, fortified milk, and cod liver oil. The sun is also a significant contributor to our daily production of vitamin D, and as little as 10 minutes of exposure is thought to be enough to prevent deficiencies.[7]
Vitamin D is not a single substance, but only 2 of the 10 or 11 sterols known to have antirachitic properties are of importance medically. These are activated ergosterol and 7-dehydrocholesterol.[8] Vitamin D is fat soluble, so it will stay in the body much longer. Mothers, make sure you are getting enough vitamin D to keep your baby healthy.[9] Vitamin D is also known as 'the sunshine vitamin.' Ultraviolet radiation from the sun is important to convert Vitamin D precursors into the active D form. This conversion takes place in the outer skin layers.[10] Vitamin D is one of the most potent vitamins. [11] Vitamin D is absorbed primarily in the duodenum and the overall efficiency of absorption is about 50%. In the liver, vitamin D is converted (by vitamin D-25-hydroxylase) into the highly active calcitriol (25-hydroxyvitamin D), which is transported through the body by a carrier protein.[12]
Vitamin D is an exception, as many people need more than the RDA. [13] Vitamin D is carried through the body by fat and stored in fat tissue. Getting too much can be harmful.[14] Vitamin D is a very potent hormone that inhibits cell proliferation. Studies have shown that vitamin D inhibits the growth of breast, colon, lung, and prostate cancer cells. Vitamin D is in foods such as egg yolks, liver, saltwater fish, and vitamin D-fortified dairy products. Vitamin D also is available in supplements, often in combination with calcium.[16] Vitamin D is also essential for heart functioning. It also plays a role in calcium metabolism.[17] Vitamin D is found only in small and highly variable amounts in butter, cream, egg yolk and liver. The best food sources are fish liver oils. Vitamin D is known to lower a blood pressure raising substance in the body called angiotensin II. If your blood 25-OH-vitamin D levels is lower than 34 ng/ml your risk of heart attack is doubled, compared to people whose levels are above 34.[19] Vitamin D is a hormone manufactured naturally in the body, and its levels can be increased with exposure to sunlight, consumption of foods rich in vitamin D, such as fatty fish, and by taking supplements. [20] Vitamin D is actually manufactured in the human skin when it is exposed to the ultraviolet spectrum of the sun's rays. Sun exposure triggers a chemical reaction with a 7-dehydrocholesterol (a form of cholesterol), which is subsequently transferred to the liver or kidneys and converted to calcidiol, a (less active) form of vitamin.[21] Vitamin D is an essential vitamin that is found in foods such as fortified milk, cereals, egg yolks, and fish. It is also produced in the skin when the skin is exposed to sunlight.[22] Vitamin D is essential for regulating blood calcium levels and for promoting calcium absorption to maintain strong bones. It also regulates certain immune functions and can decrease the proliferation of normal and cancerous cells.[23] Vitamin D is produced by the body. When your skin is exposed to ultra-violet B (UVB) radiation from the sun, vitamin D is synthesized.[24] Vitamin D is found naturally in fatty fish but few other foods. Primary dietary sources include fortified foods such as milk and some ready-to-eat cereals and vitamin supplements.[25] Vitamin D is also manufactured in the skin right after direct exposure to sunlight. Sunlight exposure to the hands, face and arms for as little as 5-15 minutes, 2-3 times per week is helpful to produce vitamin D.[26] Vitamin D is safe at reasonable doses and is relatively inexpensive. The FDA approves of 200 IU for 19-50 year olds and 400 IU for people over 50.
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