The D vitamin is one of the easiest vitamins that can be absorbed to the body, by light exposure. Half an hour per day is sufficient to assure between 10000-12000 international units of vitamin D, while the doses recommended for adults per day are between 200-600 international units each day. But it was demonstrated that the human body produces not enough D vitamin by sun light exposure.Unlike other vitamins, D vitamin is the only one that can be produced by the human body.The sun light is the trigger for vitamin D synthesis into the skin.Because is synthesize into the body, there are discussions if the D vitamin is really a vitamin or a steroid or secosteroid.A steroid is a lipid with a carbon skeleton and a secosteroid is also a steroid but with some difference in the chemical structure. The steroid by losing one ring from its chemical structure becomes a secosteroid.Because this incertitude, the D supplements effects are still under the question of its benefic effects over the human body.Although it was proved that D is a secosteroid of the human body, everyone is referring to the D complex as a vitamin. D vitamin is a fat-soluble vitamin complex, containing 2 major substances: the D2 vitamin, also called ergocalciferol and D 3 vitamin, also called cholecalciferol.

The D vitamin complex has roles in prevention of rickets at children’s and osteomalacy at adults. Bought are diseases that interfere with bone development causing bones deformations, they become thin, brittle and soft, and affect also muscle, causing muscular weakness. The D vitamin assures the right levels of calcium and phosphor in the blood. Calcium assures the normal bone growth and bone development and phosphor is involved in making strong teeth and a good muscle and nerve function. Taking calcium with D vitamin, assure a more effective absorption of calcium with 60-80 percent more than taking calcium alone. The D vitamin can be found in fortified foods, in fish liver oils or fatty fishes. Vegetarians can take they’re daily D vitamin dose from sunlight exposure and by eating vegan fortified aliments like Soya milk, breakfast cereals, vitamins or margarine.But the most important D vitamin source stays animal food, especially fishes, witch are rich in D 3 vitamin.

Taking more than 40 000 international units per day can causes toxicity. When D vitamin toxicity is observed, also an increase of calcium serum level is determinate. This is why at patients that are following a D vitamin treatment, the calcium serum level has to be very carefully measured. Cases of D vitamin toxicity were observed at persons that were following treatment for hypoparathyroidism or at children by taking to many vitamins per day. The toxicity is manifested with nausea, polydipsia, weakness or pruritus. Because of increasing the calcium level, confusion or some heart rhythm abnormalities can happen. D vitamin deficiency can occur in elder persons because of the skin that has a lower capacity of synthesize D vitamin and, at some persons that have kidney problems, the D deficiency can be more severe, because kidneys are involved in converting the D vitamin toits active forms.

Other causes of deficiency are the chronic diseases like Cronh’s disease, cystic fibrosis, cancer or autoimmune diseases. Persons that are living in the north countries, and cover the body with clothes, leaving to the sun just a little part of the skin, can also suffer from D vitamin deficiency. The supplementation of D vitamin can be useful in these cases, but there are some chronic diseases, like sarcoidosis, a rheumatic disease, where a supplement of D vitamin can be very harmful. In sarcoidosis, the metabolism of D vitamin is perturbed and excessive quantities of D vitamin and calcium are produced, causing hypervitaminosis and hypercalcemia.