Vitamin D - Benefits, Deficiency Symptoms And Food Sources
Alternative name :: Sunshine vitamin
What is Vitamin D ?
Vitamin D may not be one of the most talked about vitamins in America, but that doesn't mean it isn't among the most important. Vitamin D, a fat soluble vitamin that has properties of both a vitamin and a hormone, is required for the absorption and utilization of calcium and phosphorus.
Vitamin D is a relatively recent discovery. In 1920, a scientist named Sir Edward Mellanby found that dogs raised exclusively indoors on a limited diet developed the bone disease called rickets. After experimentation, Mellanby found that housebound dogs who regularly consumed cod liver oil (which is rich in vitamin D) didn't develop the condition.
In the early 1930s, researchers isolated in cod liver oil the substance that would later be named vitamin D. Almost simultaneously, researchers discovered that when dehydrocholesterol (a type of cholesterol found in the skin) was irradiated with ultraviolet (UV) light, an identical substance was produced. Because vitamin D could be made by the body when exposed to sunlight, it was nicknamed "the sunshine vitamin." Interestingly, although vitamin D acts like a vitamin and is known to world as a vitamin, it is chemically a steroid-a hormonal steroid, to be exact-that is built from the same 17-carbon, 4-ring structure as other steroids.
There are several forms of vitamin D, including vitamin D2 (ergocaliciferol), which comes from food sources; vitamin D3 (cholecalciferol), which is synthesized in the skin in response to exposure to the sun's ultraviolet rays; and a synthetic form identified as vitamin D5. Of the three, vitamin D3 is considered the natural form of vitamin D and is the most active.
Benefits of Vitamin D
Vitamin D is necessary for growth, and is especially important for the normal growth and development of bones and teeth in children. It protects against muscle weakness and is involved in regulation of the heartbeat. It is also important in the prevention and treatment of breast and colon cancer, osteoarthritis, osteoporosis, and hypocalcemia, enhances immunity, and is necessary for thyroid function and normal blood clotting. The vitamin D also enhances immune-system function by prompting the thymus gland to create immune-system cells, which in turn destroy bacteria, viruses, and other illness causing microbes.
The form of vitamin D that we get from food or supplements is not fully active. It requires conversion by the liver, and then by the kidneys, before it becomes fully active. This is why people with liver or kidney disorders are at a higher risk for osteoporosis. When the skin is exposed to the sun's ultraviolet rays, a cholesterol compound in the skin is transformed into a precursor of vitamin D. Exposing the face and arms to the sun for fifteen minutes three times a week is an effective way to ensure adequate amounts of vitamin D in the body. However, researchers have learned that people living in the upper third of the continental United States cannot produce adequate amounts of vitamin D from exposure to the limited available sunlight during the winter months.
Recommended Dosage of Vitamin D
The minimum Recommended Dosage Allowance of Vitamin D are :-
Special Intake of Vitamin D
While a daily dose of 10 mcg of vitamin D is recommended, the following individuals have increased needs for vitamin C :-
Deficiency Symptoms of Vitamin D
Symptoms of Vitamin D deficiency includes :-
Rich Food Sources of Vitamin D
Fish liver oils, fatty saltwater fish, dairy products, and eggs all contain vitamin D. It is found in butter, cod liver oil, dandelion greens, egg yolks, halibut, liver, milk, oatmeal, salmon, sardines, sweet potatoes, tuna, and vegetable oils. Vitamin D is also formed by the body in response to the action of sunlight on the skin. Herbs that contain vitamin D include alfalfa, horsetail, nettle, and parsley.
Some more information on Vitamin DIntestinal disorders and liver and gallbladder malfunctions interfere with the absorption of vitamin D. Some cholesterol-lowering drugs, antacids, mineral oil, and steroid hormones such as cortisone also interfere with absorption. Thiazide diuretics such as chlorothiazide (Diuril) and hydrochlorothiazide (Esidrix, HydroDiuril, Oretic) disturb the body's calcium or vitamin D ratio. Taking excessive amounts of vitamin D (over 1,000 international units) daily may cause a decrease in bone mass.
Do not take vitamin D without calcium. Toxicity may result from taking over 65,000 international units of vitamin D over a period of two years.
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