Red Clover May Prevent Bone Loss in Spine

Medically Reviewed by Charlotte E. Grayson Mathis, MD on April 16, 2004
From the WebMD Archives

April 16, 2004 -- A supplement derived from red clover may help protect women's backbones from the bone-weakening effects of age and osteoporosis.

A new study shows that women who took a red clover-derived dietary supplement containing substances called isoflavones (Promensil) experienced significantly slower bone loss in the spine compared with women who took a placebo. The supplement also appeared to have protective effects on bones in the hip, but these effects were not statistically significant.

Isoflavones found in plant foods, such as soybeans and red clover, are structurally similar to estrogen and have been proposed as an alternative to menopausal hormone therapy for the prevention of osteoporosis. Loss of estrogen is a major risk factor for osteoporosis, and women are reluctant to take menopausal hormone therapy to prevent or treat the disease because of the risks associated with it.

But researchers say previous studies that have looked at the effects of soy or other isoflavone supplements have been small and relatively short.

Red Clover May Protect Women's Bones

In the study, which appears in the February issue of the American Journal of Clinical Nutrition, researchers looked at the effects of a year of supplementation with Promensil in a group of 200 women between the ages of 49 and 65. The women were randomly divided into two groups that either took the supplement or a placebo for one year.

The study showed that women who took the red clover-derived supplement experienced a significantly lower loss of bone mineral density, bone mineral content, and blood markers of bone turnover in the lumbar (lower) spine compared with the women who took the placebo. For example, the percentage change in bone mineral density, an important sign of bone strength, in the isoflavone group was -1.08% vs. -1.86% in the placebo group.

Bone mineral density, bone mineral content, and the blood markers of bone turnover are all measures of bone health.

The researchers say decreases in bone mineral density and bone mineral content of the hip were also generally lower among those women taking the supplement compared with the women who took placebo, but these differences were not significant.

They say that these results were not entirely surprising because the hip contains more bone and is less active than the spine. Therefore, effects on bone loss in the hip may take longer to develop.

Researchers say that despite the fact that this is one of the largest and longest studies to date to look at the effects of isoflavones on bone loss, it was still relatively short-term and longer-term studies are needed to determine the impact of these supplements on other measures, such as bone fracture rates.

"Nevertheless, our findings suggest that, through attenuation of bone loss, the isoflavone supplement has a potentially protective affect on the lumbar spine," write researcher Charlotte Atkinson, of the Institute of Public Health in Cambridge, U.K., and colleagues.

Show Sources

SOURCES: Atkinson, C. American Journal of Clinical Nutrition, February 2004; vol 79: pp 326-333. News release, North American Menopause Society.

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