Controversy about whether estrogen therapy carries more risks than benefits for post-menopausal women has led some women and their doctors to seek alternatives, one of the most promising being soy supplements. Soy contains compounds called phytoestrogens, which can simulate the effects of estrogen in the body and possibly slow down some of the consequences of aging, such as bone loss, increased cholesterol, and dementia. However, soy may not be the panacea that some researchers hoped, a unique new study concludes.

What the researchers wanted to know: Does soy improve bone loss, cholesterol level, and mental facilities?

What they did: Researchers in the Netherlands took a random sample of about 200 women between the ages of 60 and 75 years involved in a breast cancer screening program. All of the women received a dietary supplement to take for a year—half got a soy mixture and the other half got a placebo, powdered milk. Both before and after the yearlong trial, the researchers tested the women's bone density, cholesterol levels, verbal skills, and memory.

What they found: There were no differences in the health of the women who took soy supplements for a year versus those who had taken powdered milk. In all tests of bone density, cholesterol, verbal skills, and memory, both groups showed similar effects of aging. The one effect that the researchers did find was that women who had gone through menopause fairly recently seemed to benefit more from soy than older women did—the younger women's bone density improved when they took soy.

What it means to you: Other studies have found that soy and other foods with phytoestrogens, like fruits and nuts, may help prevent the onset of aging, but it doesn't look like they can reverse it. Previous studies have suggested these foods might have benefits such as improved memory skills, but most used either animals or college students as their subjects, so they're hard to apply to post-menopausal women.

Caveats: The researchers only looked at some of the primary consequences of aging—bone loss, memory and verbal skill loss, and increased cholesterol levels, so there could be other effects of soy that escaped their attention.

Find out more: A page with lots of information about menopause and hormone therapy, including many links, is available directly from the National Institutes of Health.

Read the article: Kreijkamp-Kaspers, S., Kok, L., Grobbee, D.E., deHann, E.H.F., Aleman, A., Lampe, J.W., Y.T. vanderSchouw. "Effect of Soy Protein Containing Isoflavones on Cognitive Function, Bone Mineral Density, and Plasma Lipids in Postmenopausal Women: A Randomized Control Trial." Journal of the American Medical Association. July 7, 2004, Vol. 292, No. 1, pp. 65–74.

Abstract online: http://jama.ama-assn.org