Osteoporosis Prevention & Treatment (cont.)

Dr. Truong: Vitamin D comes from the diet and the skin. Skin production of the active form of vitamin D is dependent on exposure to sunlight. Active people living in sunny regions (Southern California, Hawaii, countries around the equator, etc.) can produce most of the vitamin D they need from their skin. Therefore, in Southern California where I have my practice, vitamin D supplementation is mainly used for housebound individuals or nursing home residents. In less temperate regions such as Minnesota, Michigan, and New York, skin production of vitamin D is markedly diminished in the winter months, especially among the elderly. In that population, dietary vitamin D becomes important.

Unfortunately, vitamin D deficiency is quite common in the United States, especially among the elderly living in cold climates. In a study of hospitalized patients in a general medical ward, vitamin D deficiency was detected in 57% of the patients. An estimated 50% of elderly women consume far less vitamin D in their diet than recommended. Vitamin D deficiency is further worsened in the elderly by the lack of sun exposure. Therefore, vitamin D supplementation is vitally important for the elderly.

The Food and Nutrition Board of the Institute of Medicine recommended as adequate vitamin intake: 200 IU daily for people 19-50 years old, 400 IU daily for those 51-70 years old, and 600 IU daily for those 71 years and older. An average multivitamin tablet contains 400 IU of vitamin D. Therefore, one to two multivitamins a day should provide the recommended amount of vitamin D.

Chronic excessive use of vitamin D, especially above 2000 units/day, can lead to toxic levels of vitamin D and elevated calcium levels in blood and urine. Since various dietary supplements may also contain vitamin D, it is important to review vitamin D content in dietary supplements before taking additional vitamin D.

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Last Editorial Review: 12/11/2006