Soy Consumption Common in Women at High Breast Cancer Risk

NEW YORK (Reuters Health) Oct 06, 2005 - At least one third of women at high risk for breast cancer regularly consume soy-based foods, largely because they consider these foods to be part of a healthy diet, a new study shows. While the benefits of soy consumption for cardiovascular health have been confirmed, there is no evidence that soy foods improve breast health, particularly in non-Asian women, Dr. Carolyn Y. Fang of Fox Chance Cancer Center in Cheltenham, Pennsylvania and colleagues note. In fact, they point out, there is some evidence that high soy consumption could actually increase breast cancer risk among US women.


Dr. Fang and her team interviewed 452 women with family histories of breast cancer about how frequently they consumed soy and why. Median soy consumption was 6.32 servings per month. Forty-three percent of women had consumed at least one soy food in the past month, while 32% defined themselves as soy consumers. Soy consumers ate 18.35 servings of soy each month, on average, most commonly vegetable burgers, tofu, soymilk, soy nuts and green soybeans. Women characterizing themselves as soy consumers were more educated and more likely to eat five or more servings of fruits and vegetables each day. The most common reason for eating soy they reported was to eat a healthy diet. Forty-five percent said they believed soy foods reduced cancer risk.


Among non-consumers, the most common reason for not eating soy was lack of knowledge of how to prepare it. Seven percent said they did not eat soy because phytoestrogens in soy foods could increase breast cancer, and some said a clinician had instructed them not to eat soy foods for this reason. "Given that high levels of soy intake might increase breast cancer risk, our findings highlight the need for clear, consistent messages regarding the health benefits or risks of consuming soy foods, particularly in the context of cancer risk," Dr. Fang and her team write. They note that women who believed soy had cancer-preventing properties were less likely to have gotten their information from health care professionals than women who didn't consume soy because of a potential cancer link."Thus, health professionals should take an active role in communicating and clarifying such information to patients, consumers, and public information/media channels," the researchers write.


"The message...may simply be that we do not have enough information yet to make an informed judgment. Be that as it may, consistent health messages from all sources should help to prevent further misinformation," they conclude.

J Am Diet Assoc 2005.

Fang CY, Tseng M, Daly MB. Correlates of soy food
consumption in women at increased risk for breast
cancer. J Am Diet Assoc. 2005
Oct;105(10):1552-1558.
PMID: 16183354