DEFINITION

Vitamin D is a fat-soluble vitamin that is important for the absorption of calcium and the production of strong teeth and bones.

DESCRIPTION

Vitamin D is important for the proper absorption of calcium from food. It is vital for the control of the levels of calcium in the blood and also controls the rate at which the body excretes calcium in the urine. The calcium levels in the body need to be kept stable so that calcium is available for the growth and renewal of bone cells. Vitamin D is stored in the fat tissues of the body. Excessive levels of Vitamin D in the body cause an elevation in the blood calcium levels, increased calcium excretion in the urine, kidney stones and the formation of hard, calcium-rich deposits in the soft tissues of the body.

MEDICAL USE

Always consult your Health Professional to advise you on dosages and any possible medical interactions.
Vitamin D supplements are used medically to prevent and treat certain bone diseases, such as rickets in children and osteomalacia (softening of the bones) in adults. An adequate level of Vitamin D in the body is necessary to maintain strong bones and to help prevent fractures in older people. It is also used for people with genetic diseases that interfere with the metabolism of Vitamin D. More recently, various forms of Vitamin D have been used for the treatment of the skin condition psoriasis. These treatments include topical lotions that are applied to the skin.

Two recent studies involving 187,000 nurses over a 20-year period has found a relationship between vitamin D intake and the development of multiple sclerosis. The results indicate that taking a daily multi-vitamin supplement containing vitamin D may reduce the risk of developing multiple sclerosis. The same benefit was not seen in people exposed to high levels of sunlight or in those eating vitamin D-rich foods.

Vitamin D also controls the responses of the immune system. Slightly modified forms of Vitamin D have recently been given to people with autoimmune diseases (e.g. lupus) to control their immune system responses and reduce the required dosages of other immunosuppressant medications. Some forms of Vitamin D also decrease the rate at which cells divide and may be used in the future to control the growth of certain cancers.

DEFICIENCY

Dietary deficiency of Vitamin D causes rickets (mainly seen in children). Rickets causes weak, deformed and porous bones; muscle cramping and twitching; burning sensations in the mouth and throat; sweating from the scalp, particularly at night; and slow growth in children.

SOURCES

The major source of Vitamin D in active people is sunlight, as exposure of the skin to sunlight produces Vitamin D in the body. Good food sources of Vitamin D include milk, fatty fish such as salmon and mackerel, cod liver oil, fish liver oil, some breads and cereals and egg yolks.

DOSAGE

The recommended dietary allowance (RDI) for Vitamin D is 200 IU per day for adults and 400 IU per day for women who are pregnant or lactating and for children under the age of 10 years. Long-term use of Vitamin D supplements and/or high doses of Vitamin D should only be taken under medical supervision. See your health care professional for advice about the correct dosage for you.

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