Women with Osteoporosis May Need More Vitamin D

By Jeremy Appleton, ND, CNS

Healthnotes Newswire (March 16, 2006)—More than half of American women receiving drug therapy for osteoporosis are deficient in vitamin D, according to the Journal of Clinical Endocrinology and Metabolism (2005;90:3215–24). Vitamin D is essential for calcium absorption and metabolism and is required for healthy bones and to protect against osteoporosis. The new research suggests that many women with osteoporosis are using drugs to treat a problem that could be helped simply by getting sun more often or by taking a nutritional supplement.

Researchers measured blood levels of vitamin D and parathyroid hormone (which regulates calcium metabolism) in 1,526 postmenopausal women whose average age was 71. The optimal blood level of vitamin D remains a matter of debate, but the authors used 30 nanograms/milliliter (ng/ml) as a cutoff point below which women were considered deficient. Just over half the women studied were vitamin D–deficient. The prevalence of suboptimal vitamin D was also more pronounced among women who took less than 400 IU per day of vitamin D as a supplement.

The conclusions of this study are limited, because the authors studied North American women only during the winter months, when blood vitamin D levels tend to be at their lowest. Because they studied almost exclusively white women, their results cannot be extrapolated to other racial groups. Nonwhites have been reported to have an even higher rate of vitamin D insufficiency.

Osteoporosis is a common disease in which bones become porous and brittle and lose their mass. As a result, bones become more susceptible to fractures. Both men and women are affected by osteoporosis, but it is more common in women. According to the National Institutes of Health, 10 million Americans have osteoporosis and an additional 34 million have low bone mass, putting them at increased risk for the disease. In the United States, half of all women over 50 (and a quarter of all men that age) will have an osteoporosis-related fracture in their lifetime, usually of the hip, spine, or wrist. Because of the central roles nutrition and lifestyle play in bone health, osteoporosis is very much a preventable disease.

The recommended daily intake of vitamin D is 400 IU for women ages 51 to 70 and 600 IU for women 70 years and older. The most important source of vitamin D is sunshine. When the skin is exposed to ultraviolet light, it makes vitamin D (some estimates say the body can get sufficient vitamin D from a daily 20-minute exposure of face and arms). Many elderly women and men become deficient in vitamin D because they spend most or all of their time indoors. Vitamin D is also found in foods, primarily those of animal origin, such as fish, eggs, milk products, and meats. Mushrooms are a significant nonanimal source of vitamin D.

In addition to getting adequate vitamin D and calcium, osteoporosis risk can be reduced by making dietary and lifestyle changes, such as eating moderate amounts of animal protein, eating less salt, avoiding caffeine and soft drinks, quitting smoking, and getting regular weight-bearing exercise, such as walking.


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