Soy and Breast Cancer: 5 Myths and Facts
4. Myth: If you have or had breast cancer, avoid all soy foods. continued...
“Still, I’d recommend that breast cancer patients avoid soy supplements,” Millstine says.
In one report, researchers analyzed data from diet surveys completed by more than 9,500 American and Chinese women. Those who said they ate the most soy were 25% less likely to have their cancer return compared to those who had the least.
Some experts worried that soy might interfere with breast cancer drugs that lower estrogen levels, such as tamoxifen. But the same study showed that soy also protected against recurrence in patients who took tamoxifen.
The soy foods that the study included were tofu, soy milk, and fresh soybeans. As you might expect, the Chinese women ate far more of it than those in the U.S. The results still held when the researchers considered that fact.
5. Myth: Soy only affects breast cancers that are sensitive to estrogen.
While it’s true that soy isoflavones play a bigger role in estrogen-receptor positive breast cancers, early research links it to a lower risk of other types of breast cancer.
That finding comes from a study of 756 Chinese women who had breast cancer and about 1,000 others who didn’t have the disease. All of the women answered questions about their diets, including how much soy they ate. Those who said they ate more soy were less likely to have any type of breast cancer, compared to those who ate the least.
That finding doesn’t prove that soy prevented breast cancer in any of the women. Other things could be involved.
“More research still needs to be done,” Meyers says. “It could be that people who eat more soy have healthier lifestyles in general.”
Stay tuned to see if that proves to be helpful across the board, whether you eat tofu regularly, pour soy milk on your breakfast cereal, or snack on edamame.