Last week I blogged about what to
eat right now for better breast health
. I received a lot of comments—and concerns—from readers, mostly on the topic of soy
. A few months ago, I too started
wondering about the connection between soy and breast health. Soy is touted as a food that can prevent breast cancer—and also
implicated as one that might promote it. In the last year, I’ve increased how much soy I eat each week because I’ve been
eating a more vegetarian-based diet. (Get
recipes for some of my favorite meatless meals here.
) So, I wanted to know what the science said: is soy safe or
• Researchers still don’t know whether isoflavones—the compounds in soy that act as weak estrogens in
the body—spur the growth of tumors by acting like estrogen or prevent breast cancer by competing with the breast’s
natural estrogen. Scientists who looked at the effect individual isoflavones from soy had on breast-cancer cells in test
tubes have found both results.
• Recent studies, however, which looked at dietary habits, are helping scientists to better
understand who might reap the greatest protection from soy. One study of nearly 74,000 Chinese women, age 40 to 70,
found those who consumed a daily serving or more of soy had a significantly lower risk of developing breast cancer in their
premenopausal years than women who ate soy less frequently. Also in this study, the women who started eating soy consistently
in adolescence had an even lower risk than those who started later. However, in this study eating soyfoods did not protect
women from developing breast cancer after menopause.
• Studies are conflicting about the benefits of soyfood consumption later in life.
hypothesize that in younger women, when the body’s estrogen levels are high, isoflavones in soy may compete with the body’s
natural estrogen and reduce risk of breast cancer. After menopause, however, natural estrogen levels are much lower and so
it’s thought that the isoflavones act like estrogen. Higher estrogen levels are linked with higher risk for breast cancer.
That doesn’t mean that eating soyfoods like tofu and edamame—in moderation—after menopause is unsafe, as there’s no data to
show that eating soyfoods increases breast-cancer risk in postmenopausal women. (Find 10 delicious recipes using
edamame, tofu and more soy ingredients.
The Bottom Line:
Adding soy to your diet in midlife might not offer much protection against
breast cancer. But it probably won’t hurt either: soyfoods are a healthy, protein-rich, low-saturated-fat alternative to
foods like red meat. Because theoretically soy isoflavones can act like estrogen, it’s best to eat soyfoods in moderation at
any age—up to two servings daily, which is equivalent to 1/2 cup tofu or edamame and 1 cup soymilk. Enjoy soy in Tofu
Parmigiana and 25 more delicious tofu recipes.