Vitamin D is also sometimes used to treat other diseases in which calcium is not used properly by the body. Vitamin D is fat soluble, meaning it is stored in your fat cells. It is not excreted daily like many other essential nutrients and can build up to unhealthy levels.

Vitamin D is needed to keep a balance between calcium and phosphorus in the body by controlling how much is absorbed from foods, or taking them from bones when needed. Vitamin D is best known for its role in building bones and keeping them strong.

Vitamin D is manufactured in the skin after direct exposure to sunlight. Exposing the hands, face or arms to direct sunlight for 15 minutes two or three times per week will help produce vitamin D.

Vitamin D is best absorbed when ingested with lipids. Vitamin D will be incorporated into micelles and these will be absorbed by the intestine by passive diffusion. Vitamin D is a secosteroid hormone, and the body regulates the production of all it needs. In fact, the use of supplements can be harmful, because they suppress the immune system so that the body cannot fight disease and infection effectively.

Vitamin D is found in food, but also can be made in your body after exposure to ultraviolet rays from the sun. There are several different forms of vitamin D. Vitamin D is involved in regulating cell growth and differentiation and in essential immune system functions.

With this knowledge, scientists are exploring links between low vitamin D status and increased risk for a number of chronic diseases, including some types of cancer, heart disease, type 1 diabetes, rheumatoid arthritis, and multiple sclerosis. Vitamin D is not really plentiful in the diet. Fatty fish, such as salmon, tuna and sardines, are rich sources.

Vitamin D is needed to properly absorb calcium. Calcium, together with vitamin D, can help heal bone fractures from osteoporosis and decrease the risk of future bone breaks. Vitamin D is a steroid hormone that exists in two molecular forms: vitamin D-3 (cholecalciferol) found in animal skin, and vitamin D-2 (ergocalciferol) found in yeast. These two forms are created by the action of the sun’s ultraviolet rays on the biological precursors 7-dehydrocholesterol and ergosterol.

Vitamin D is essential for promoting calcium absorption in the gut and maintaining adequate serum calcium and phosphate concentrations to enable normal mineralization of bone and prevent hypocalcemic tetany. It is also needed for bone growth and bone remodeling by osteoblasts and osteoclasts [4-6 ].

Vitamin D is not prevalent in foods. Only 29 percent of commercial milk samples tested were within 80 to 120 percent of the amount stated on the label. Vitamin D is known as the “Sunlight Vitamin” because our body normally manufactures its own Vitamin D upon exposure to sunlight.

Breast milk has been found to have only trace amounts of vitamin D, even when the mother gets the recommended daily allowance. Vitamin D is also found in supplements. For those who feel they may not be getting enough vitamin D from foods or sunlight, and you are in one of the high risk groups for deficiencies, you may consider taking vitamin D supplements.

Vitamin D is converted in the liver into calcidiol (25-hydroxyvitamin D), which in turn is transformed in the kidneys into calcitriol (1,25-hydroxyvitamin D). Calcitriol is the major active form of vitamin D, and it is secreted into the blood to help regulate calcium (Ca) in the body in conjunction with some other systems including the parathyroid hormone.