Breast Cancer Risk: Does Soy Help?
Studies Suggest That Eating Soy May Slightly Lower Risk of Developing Breast Cancer
Health Claims Aren't Proven
Trock tells WebMD that the 18 studies did not prove or disprove the protective benefits of eating soy foods. The risks vs. benefits of taking soy supplements were not addressed in the study because the women were asked about the foods they ate.
None of the studies indicated that eating soy foods increased breast cancer risk, but Trock says the jury is still very much out on soy supplements.
Nutritionist and epidemiologist Maria Elena Martinez, PhD, says many high-risk women and breast cancer survivors may be taking soy supplements instead of hormone therapy for menopausal symptoms because they believe them to be safer.
"The truth is, we don't know if these products are safer because they haven't been studied," she says. "And because they aren't regulated, you don't know what you are getting."
Complexity of Cancer
Ads for soy supplements make a wide range of health claims about the products. Studies examining the role of soy in reducing hot flashes and other menopausal symptoms have been mixed, however, and most have not shown a protective benefit for lowering cholesterol and preventing Alzheimer's disease and osteoporosis.
Trock says it is not surprising that the soy studies and most other studies examining the role of specific foods in cancer risk have failed to show clear associations.
"Cancer takes decades to develop and it is influenced by many things," he notes. "People want to know in simple terms what they can do to reduce their risk, and we can't always tell them. We have to get across the idea that cancer is a complicated process. If we are lucky we may find that a single food or a single nutrient is protective, but so far that hasn't happened."