Postmenopausal fracture: soy consumption appears to reduce the risk

The consumption of soy may protect bone in postmenopausal women menopausal fracture risk, especially during the first decade after menopause, if you believe the results of a large epidemiological study in China whose findings are published in the "Archives of Internal Medicine."
Soy isoflavones, also called phytestrogènes because of their resemblance to human estrogen, enter into the composition of many dietary supplements and found naturally in soy beans, nuts and clover, for example. Their use has been suggested as an alternative to hormone replacement therapy for menopause, since the consumption of these molecules present less significant than those associated with estrogen replacement risk of adverse effects.

In vitro studies have suggested that these particular molecules are also able to inhibit bone resorption and stimulate bone formation. However, while these properties suggest a beneficial effect of isoflavones on the maintenance of bone mineral density (BMD, an indicator of the risk of osteoporotic fracture) sufficient for the moment, no large-scale study has sought to assess the direct link between soy consumption and the risk of fracture, reported Dr. Xianglan Zhang, of Vanderbilt University School of Medicine (Nashville, Tennessee) and colleagues.

To clarify this point, the researchers of this Sino-American team analyzed data collected as part of the "Shanghai Women's Health Study." Conducted among a cohort of approximately 75,000 Chinese aged 40 to 70 years, this survey has tracked women whose diet naturally has many soy products.

Were selected for inclusion in this new study participants with no history of postmenopausal fractures or cancer, having never taken hormone replacement therapy, or 24,403 women. Their dietary habits were determined through a questionnaire on the frequency of consumption of different types of food, which was submitted to them regularly. Participants were then interviewed 4.5 years later about the possible occurrence of osteoporotic fractures

A total of 1770 fractures were recorded during the observation period.

The more precise analysis of these cases showed a higher consumption of soy protein was significantly associated with a lower risk of fracture. This association remains when the results are adjusted to take into account the influence of other parameters such as age, caloric intake, socioeconomic status, calcium intake, protein from non-soy, fruits and vegetables, or risk factors for osteoporosis.

This protective effect of soy protein was particularly evident in postmenopausal women for less than ten years. Indeed, in this particular population, women with the consumption of products containing the highest soy proved almost twice as likely (48%) than those eating little soy to make such a fracture.

However, postmenopausal women for more than ten years, the reduction in fracture risk observed in large consuming soy versus small, only reached 29%.

Similar results were also obtained for the intake of isoflavones, the authors note.

"Soy consumption could be particularly beneficial to compensate for the decreased bone mineral density associated with menopause," suggest the authors, who go on to suggest that this approach could instead "be less effective in reversing the trend once that bone loss is established. "

However, they warn, "this observational study can not establish a causal relationship between soy consumption and reduced risk of fracture." Indeed, despite the fact that they have rigorously analyzed other factors that may influence this risk, the possibility that other influences have been neglected can not be excluded, they note.

In addition, further studies are still needed before these results can be considered as being generalized to other populations such as postmenopausal Chinese women living in urban areas.