Soy Consumption Reduces Bone Fracture Risk in Postmenopausal Women

Reuters
09/12/2005
 

NEW YORK (Reuters Health) Sept 12 - Eating soy products protects the bones of older women, particularly those in early menopause, according to results of a large, prospective cohort study in China.

Soy isoflavones are believed to suppress bone resorption and stimulate bone formation. While in vivo and in vitro studies have suggested that soy phytoestrogens help sustain bone mineral density, there have been no large studies assessing the association between soy consumption and the risk of fracture, Dr. Xiao-Ou Shu and colleagues note.

The research team therefore analyzed data from the Shanghai Women's Health Study, conducted in a population that has a wide range of soy food consumption. They report their findings in the Archives of Internal Medicine for September 12.

Included in their analysis were postmenopausal women with no history of fracture or hormone therapy use who completed a quantitative food frequency questionnaire, then were questioned approximately 4.5 years later regarding the incidence of fractures.

The roughly 24,000 women reported a total of 1770 incident fractures. Higher soy protein consumption was significantly associated with lower risk of fracture, even after adjusting for age, calorie intake, socioeconomic status, other nutrients, and osteoporosis risk factors, report Dr. Shu, from the Vanderbilt University School of Medicine in Nashville, Tennessee, and associates.

The protective effect was most evident among women within 10 years of menopause; for this subgroup, the relative risk of fracture was 0.52 among those in the highest quintile of soy protein intake compared with those in the lowest quintile (p < 0.001 for trend). For women who had been menopausal for greater than 10 years, the relative risk was 0.71 in the highest quintile (p = 0.009 for trend).

"Soy consumption may be particularly beneficial in preventing menopause-related bone loss," the authors suggest, "but less effective at reversing established bone loss."

However, they add, other studies will be needed before generalizations to other populations can be made.

Arch Intern Med 2005;165:1890-1895.