After years of controversy and confusion about whether breast cancer survivors should eat soy, scientists have concluded that soy food does not increase the risk of cancer recurrence or death among breast cancer survivors, according to a large study from the Vanderbilt-Ingram Cancer Center (VICC) in Nashville, Tenn.
The study included several research institutions in China and the U.S.
“There has been widespread concern about the safety of soy foods for women with breast cancer,” lead author Xiao-Ou Shu, professor of Medicine at VICC said in a press release. “Soy foods contain large amounts of isoflavones that are known to bind to estrogen receptors in cells and have estrogen-like and anti-estrogenic effects.”
Shu said the results indicated it may be beneficial for women to include soy food as part of a healthy diet, even if they have had breast cancer.
The study assessed the diets of 9,515 breast cancer patients, including soy foods like tofu, soy milk, cooked soybeans, miso soup, soybean sprouts and protein shakes with added soy.
Women who ate the most soy food—more than11.83 milligrams of isoflavones per day—had a 27 percent reduced risk for breast cancer recurrence, compared to those with the lowest soy diet.
“Our results indicate it may be beneficial for women to include soy food as part of a healthy diet, even if they have had breast cancer,” Shu said.
He added that the results should not be generalized to soy supplements because they may differ from soy foods in both the type and amount of isoflavones.
Women can get the amount of soy isoflavone that is similar to the level in the study by drinking a cup of soy milk or eating two ounces of tofu per day.
The study was presented at the American Association for Cancer Research (AACR) annual meeting in Orlando, Fla.