High-soy diets can reduce the risk of breast cancer recurrence and death.
Soy’s connections to breast cancer now questioned
September 22, 2010
Where it was once believed too much soy in a diet could increase the risk of developing breast cancer, newer findings suggest high-soy diets can reduce the risk of breast cancer recurrence and death. The contradiction, in part, is prompting some health providers to clarify what food sources are best for delivering soy protein.
Then and now
Soybeans and soy products (such as soymilk, tempeh, miso and tofu) contain chemicals called isoflavones, a type of phytoestrogen that may imitate the effects of estrogen in the body. Institutions like The Pennsylvania State University‘s College of Agricultural Science and Susan G. Komen for the Cure caution that, because isoflavones are weak estrogens, and because high levels of estrogen have been linked with breast cancer cell growth, adding large amounts of soy and soy products to your diet may increase your risk of developing breast cancer.
However, Asian women, who typically consume high levels of soy, have lower incidences of breast cancer than U.S. women, according to the World Health Organization. And a 2009 study involving 5,042 Chinese female breast-cancer survivors, reported in The Journal of American Medical Association, found that diets with high levels of soy reduced the risk of breast cancer recurrence and death.
While Caucasian U.S. women eat much smaller amounts of soy than Chinese women, the soy Americans eat is typically more highly processed, and Americans don’t typically begin eating soy at an early age as Chinese women do, according to the Susan G. Komen for the Cure Web site, which further suggests that these differences may make the study findings from Asia inconclusive when it comes to Caucasian women in the U.S.
“Soy is a component of a diet in an Eastern culture, and we (Westerners) try to fit it into our context,” agrees Steven Ehrlich, a doctor of naturopathic medicine in Phoenix. “It’s not whether we eat soy, it’s how we eat it that’s important.”
MedlinePlus reports that soy may reduce symptoms of menopause and the risk of osteoporosis. The University of Maryland Medical Center‘s Web site reports studies that suggest soy may control blood sugar and lower LDL (bad) cholesterol in postmenopausal women with type 2 diabetes, and reduce blood pressure and arterial stiffness in overweight men and postmenopausal women.
If you wish to eat soy products, the best sources, according to Prevention, are those that are lightly processed, or that have whole soy protein, or powdered soy protein that contains at least 60 mg of isoflavones.
Ehrlich believes the best way to eat soy is in its natural state and with a well-balanced meal. “If a woman wants to eat edamame with vegetables and salmon, that’s fantastic, because the soy is a component of a meal and in its natural form, not in a protein, and not synthesized to a megadose,” he said. “There’s a certain wisdom in nature’s design — you don’t see soy protein drinks hanging from trees.”
Before you decide to introduce soy into your diet, talk to your doctor.