Recent research has brought reassurance to women who enjoy soyfoods, especially those who have had breast cancer. Last year, both the American Cancer Society and the American Institute for Cancer Research concluded that women with breast cancer can safely consume soyfoods. And now, another study adds even more support to that stance.
Researchers from the University of Hawaii Cancer Center examined the effects of two diets on breast fluid in 96 premenopausal women. The women consumed diets containing either two servings of soy per day (the high-soy diet) or less than three servings per week (the low-soy diet) for six months. At the end of this first part of the study, there was a one-month washout period where the women ate their usual diets. Then they switched to consume the other test diet. This way, all of the women in the study consumed both the high- and low-soy diets for six months each.
The researchers collected breast cells and breast fluid using a noninvasive technique that is similar to a breast pump. When the cells were analyzed, there was no effect of soy consumption on structure or function of the cells. There was, however, some evidence to suggest that during the consumption of the high-soy diet, the cells were affected in a way that makes them less likely to become cancer cells. For the purposes of this study, a serving of soy was defined as ¾ cups of soymilk, 4 ½ ounces of tofu, or about ¼ cup of soynuts.
The authors concluded that this study, along with the results of other similar research, suggests that consuming soyfoods in amounts that are typical of Asian intake is safe.
Maskarinec et al. Nutrition and Cancer, 2013