Vitamin D


Vitamin D (or calciferol) is a vitamin which promotes calcium absorption (after exposure to sunlight), essential for normal development of bones and teeth, it also acts as newly discovered immune system, heart, brain and the secretion of insulin from the pancreas. It is a fat-soluble vitamin obtained from cholesterol by as metabolic precursor of sunlight and dietary sources. Functionally, vitamin D acts as a hormone that maintains the calcium and phosphorus in the blood by increasing or decreasing the absorption of these minerals in the small intestine.Vitamin D also regulates bone metabolism and calcium deposition in bones. The name of the vitamin was created by the Polish biochemist Casimir Funk in 1912, based on the Latin word vita (life) and the suffix-amine. It was initially used to describe these substances from the amine functional group, since that time it was thought that all vitamins were amines.Despite the error, the name remained. Vitamin D is also very important for children, pregnant and lactating mothers, by increasing growth and allow the determination of calcium in bone and tooth. Besides the importance in maintaining calcium levels in blood and bone health, vitamin D has an important role in most metabolic functions and also in muscle function, cardiac and neurological disorders. The vitamin D deficiency can precipitate and exacerbate osteoporosis in adults and cause rickets, a avitaminosis in children.

Vitamin D: More Details

Exposure to sunlight triggers the production of vitamin D in the skin. Some foods also represent a source of this vitamin. The cod liver oil was also used as a food supplement to prevent rickets, being nowadays easily replaceable by medicines containing vitamin D, but vitamin D from sunlight is still preferable.
Vitamin D is found in two forms: ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3). The ergocalciferol is commercially produced from ergosterol found in plants and yeast, through irradiation with ultraviolet light. It is used as a food supplement for the enrichment of foods such as milk with vitamin D. Cholecalciferol is converted by the action of sunlight from the provitamin D3 (7-dehydrocholesterol) found in human skin. Both forms D2 and D3 are hydroxylated in the liver and kidneys to 25-hidroxicalciferol and then to the biologically active form, 1,25-di-hidroxicalciferol (calcitriol), which acts as a hormone in the regulation of calcium absorption in the gut and regulation levels of calcium in bone and kidney.
Vitamin D is essential for calcium homeostasis in the body. Like other vitamins should be consumed in adequate amounts, avoiding shortages and excesses.
The amount of vitamin D that an adult needs varies according to age, 5 mg to 10 mg, reaching 15 mg in the elderly over 70 years. Few foods are considered sources of vitamin D, but among them are the egg yolk, liver, butter and certain types of fish such as mackerel, salmon and herring. Although to a lesser extent, sardines and tuna also have vitamin D.
In the United States of America is required that the milk is enhanced with vitamin D. Other foods and drinks can also be enhanced with vitamin D in the U.S., including ready to eat breakfast cereals, milk products, soy drinks and juices, but they are insufficient alone.


In the liver, Vitamin D is converted into a form that can be transported by blood. Kidney, this form is modified to produce hormones derived from vitamin D, whose primary function is to increase calcium absorption in the intestine and facilitate normal bone formation. Deficiency in vitamin D, calcium and phosphate in the blood decreases, causing a bone disease because there is a sufficient amount of calcium available to maintain healthy bones. This condition is called rickets in children, a disease that manifests as delayed closure of fontanelle in neonates (important in the skull), bone demineralization, twisted legs and other signs related to bone structure. It is called osteomalacia in adults, where it grows soft and weak bones. The vitamin D deficiency is caused mainly by lack of sunlight exposure rather than with vitamin D in the diet, as demonstrated by new independent studies. This deficiency can occur in the elderly because the skin makes less vitamin D, even when exposed to sunlight, but also the wrong recommendations of doctors to advise supplements of vitamin D because exposure to sunlight, or by excess sunscreen! A deficiency of vitamin D during pregnancy can cause rickets and osteomalacia in women in the fetus. Vitamin D has little chance of becoming toxic in the body, because when the skin does not make your cholesterol present in inactive vitamin D (and only activated in the liver and kidneys), the sun’s rays destroy the vitamin naturally.

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  1. One Response to “Vitamin D”

  2. By Monalisa on Aug 19, 2012 | Reply

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