Soyfood consumption linked to decreased risk of breast cancer, finds study

A major new study published in the Journal of the American Medical Association (JAMA) finds that women with breast cancer would be well-served by including soyfoods in their daily diet. Soyfood consumption was significantly linked to a decreased risk of death and cancer recurrence among the breast cancer patients in this study. Benefits increased up to about 11 grams of soy protein (about two servings) per day; beyond that amount, there was no additional benefit.

The Shanghai Breast Cancer Survival Study - led by Xiao Shu, MD, PhD, of Vanderbilt University in Tennessee and the Shanghai Institute of Preventative Medicine in China - evaluated 5,042 breast cancer patients. The research team recruited women aged 20 to 75 to participate in the study approximately six months after their cancer diagnosis and tracked their health over four years.

The findings show that the women in the study who consumed higher amounts of soy protein had a 7.4 percent mortality rate and an 8.0 percent cancer recurrence rate. In contrast, the women who consumed the least amount of soy had a 10.3 percent mortality rate and 11.2 percent recurrence rate. Thus, soyfood intake was associated with about a 30 percent decrease in risk.

The study documented these lower mortality and cancer recurrence rates for women in the highest soyfood intake group regardless of menopausal status, whether they had estrogen receptor-positive or -negative breast cancer (the two types of breast cancer) and whether or not they were prescribed the breast cancer drug tamoxifen. In fact, the findings suggest that high soyfood intake and tamoxifen use may have comparably beneficial effects on breast cancer outcomes.

"Women with breast cancer can use the information from this unique study to feel comfortable incorporating soyfoods into their diet," said Mark Messina, PhD, a scientific advisor to the United Soybean Board. "This research also gives the professional health community new data to consider for better patient care."

The study's authors plan to continue tracking the participants' mortality and cancer recurrence rates and suggest more studies are needed to confirm their findings. Nevertheless, an editorial by Rachel Ballard-Barbash, MD, MPH, of the National Cancer Institute and Marian L. Neuhouser, PhD, of the Fred Hutchinson Cancer Research Center, published by JAMA alongside the study, notes that "clinicians can advise their patients with breast cancer that soyfoods are safe to eat and that these foods may offer some protective benefit for long-term health."

Dr. Ballard-Barbash and Dr. Neuhouser continue, "patients with breast cancer can be assured that enjoying a soy latte or indulging in pad thai with tofu causes no harm, and when consumed in plentiful amounts, may reduce risk of disease recurrence."

To add soy to your diet, download easy recipes from the United Soybean Board's SoyConnection.com, or simply:

• Add soymilk to pancakes, smoothies or coffee drinks at breakfast
• Zap frozen edamame in the microwave and sprinkle with spices
• Puree an edamame hummus in 5 minutes
• Mix soynuts into trail mix for an on-the-go snack
• Lightly pan-fry tofu fingers and dip in your favorite sauce
• Stir-fry lean meats, tofu and vegetables in soybean oil