disorders of nutrition
Vitamin D Deficiency
Introduction
Vitamin Ddeficiency is most commonly caused by a lack of exposure to sunlight. Some disorders can also cause the deficiency. The most common cause is lack of exposure to sunlight, usually when the diet is deficient invitamin D, but certain disorders can also cause the deficiency. Without enoughvitamin D, muscle and bone weakness and pain occur. Infants develop rickets: The skull is soft, bones grow abnormally, and infants are slow to sit and crawl. Blood tests and sometimes x-rays are done to confirm the diagnosis. From birth, breastfed infants should be givenvitamin Dsupplements because breast milk contains littlevitamin D. Vitamin Dsupplements taken by mouth or given by injection usually result in a complete recovery. (See also Overview of Vitamins .) Two forms ofvitamin Dare important for nutrition: Vitamin D2 (ergocalciferol):This form is synthesized from plants and yeast precursors. It is also the form usually used in high-dose supplements. Vitamin D3 (cholecalciferol):This form is the most active form ofvitamin D. It is formed in the skin when the skin is exposed to direct sunlight. The most common food source is fortified foods, mainly cereals and dairy products.Vitamin Dis also present in fish liver oils, fatty fish, egg yolks, and liver. Vitamin Dis stored mainly in the liver. Vitamin D2 and D3 are not active in the body. Both forms must be processed (metabolized) by the liver and kidneys into an active form called activevitamin Dorcalcitriol. This active form promotes absorption of calcium and phosphorus from the intestine. Calcium and phosphorus, which are minerals, are incorporated into bones to make them strong and dense (a process called mineralization). Thus,calcitriolis necessary for the formation, growth, and repair of bones. may be used to treat Psoriasis , Requirements forvitamin Dincrease as people age. , like vitamins A, E, and K, is a Fat-soluble vitamins , which dissolves in fat and is best absorbed when eaten with some fat. Vitamin Ddeficiency is common worldwide. Invitamin Ddeficiency, the body absorbs less calcium and phosphate. Because not enough calcium and phosphate are available to maintain healthy bones,vitamin Ddeficiency may result in a bone disorder called rickets in children or osteomalacia in adults. In osteomalacia, the body does not incorporate enough calcium and other minerals into bones, resulting in weak bones. deficiency makes Osteoporosis worse. level becomes high (a condition called Hyperparathyroidism ), the hormone draws calcium out of bone to increase the calcium level in blood. Lack of exposure to sunlight can causevitamin Ddeficiency. 