Nutrition Vitamin D

Vitamin D is the only fat soluble vitamin which can be endogenously produced in the skin when the ultraviolet rays from the sunlight strike the skin. Vitamin D is essential for an optimal bone health as it promotes the absorption of calcium in the gut and maintains adequate serum calcium and phosphate levels in the body which ensures normal mineralization of the bone. Vitamin D is also needed for bone growth and bone remolding by osteoblasts and osteoclasts; an inadequate levels of vitamin D can cause thin, brittle or misshapen bones. Vitamin D along with calcium helps to prevent and protect older adults from osteoporosis. Also other bone diseases like rickets in children and osteomalacia can be prevented with sufficient Vitamin D.

Vitamin D also plays other important function in human body that is reduction of inflammation and modulation of neuromuscular and immune function. Health benefits of vitamin D have been seen in studies preventing cancer, autoimmune diseases and psoriasis too. There are two forms of vitamin D namely ergocalciferol or vitamin D2 and cholecalciferol or vitamin D3. Calciferol the active form of vitamin D can be synthesized in the kidneys form vitamin D2 or D3.

Besides being produced by the body, naturally very few foods are good source of vitamin D. Vitamin D2 is found in fungal and plant sources and vitamin D3 is found mainly in animal sources. The major dietary source for vitamin D is fortified foods. Vitamin D also naturally occurs in fatty fish like mackerel, salmon, fish liver oil, cod liver oil, milk, egg yolk and some breads.

Vitamin D Deficiency and Toxicity
Vitamin D deficiency in adults can lead to softening of bones also known as osteomalacia. In children vitamin D deficiency can cause rickets which can lead to bowing of the bones (not seen in adults). Vitamin D deficiency can be caused in individuals who live in conditions that have little or no exposure to sunlight. People suffering from other diseases like Crohn’s disease, cystic fibrosis, chronic liver disease or Whipple’s disease and sprue are also prone to have vitamin D deficiency.

Vitamin D can cause a health risk when consumed in excess amounts. Too much vitamin intake (more than 1000 IU daily) can cause side effects like excessive thirst, poor appetite, metal taste, tiredness, bone pain, weight loss, vomiting, diarrhea, constipation, itching skin, sore eyes, and muscle problems. Excess vitamin D can also lead to excessive absorption of calcium which can result in high serum calcium levels which can in turn lead to bone loss, kidney stones and calcification of other organs like heart and kidneys.

Submitted on February 24, 2009