Consuming soy may be associated with a small reduction in breast cancer risk, but the reduction is not big enough or clear enough to suggest women should be taking soy supplements.
“When you put it all together, we came up with evidence of a small protective effect but a lot of reasons to be a little wary of how accurate that effect may be,” said study author Bruce Trock, an associate professor of urology at the Johns Hopkins School of Medicine.
“The bottom line is we don’t know if it’s helping, hurting or doing anything at all,” added Dr. Jay Brooks, chairman of hematology/oncology at the Ochsner Clinic Foundation in Baton Rouge, La. Brooks was not involved with the study, which appears in the April 5 issue of the Journal of the National Cancer Institute.
Asian women have lower breast cancer rates (39 per 100,000) than Western women (133 per 100,000) and, when Asian women migrate to the United States, their breast cancer rates tend to go up. This suggests that an environmental factor, perhaps related to diet, is at play.
Attention has zeroed in on soy products (consumed more in Asia) as they contain high quantities of isoflavones, molecules that affect pathways that could change breast cancer risk. Indeed, more and more women are taking high-dose soy or isoflavone supplements because of their perceived benefits, which include lowering LDL (“bad”) cholesterol.