Soy Food Reduces Bone Fractures in Older Women

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

While other studies have suggested that the plant estrogens found in soy 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 in the Archives of Internal Medicine.

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.

The analysis included postmenopausal women with no history of fracture or hormone therapy use who completed a food frequency questionnaire, then were questioned approximately 4.5 years later regarding the occurrence of fractures.

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

The protective effect was most evident among women who were within ten years of menopause. For this subgroup, the risk of fracture was reduced by 48 percent among those with the highest intake of soy protein intake compared to those in the lowest consumption.

For women who had been menopausal for more than ten years, the risk reduction was 29 percent.

"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.

SOURCE: Archives of Internal Medicine, September 12, 2005.