You may have seen some scary headlines about meat being linked to cancer, but don't blame protein. It turns out that eating a moderate amount of protein doesn't appear to cause breast cancer. In fact, protein may have some protective effects in women who've already had the common cancer, according to a new study published in the Journal of Clinical Oncology.
This jives with previous research finding that eating a diet high in protein and low in carbs may reduce the risk of cancer and slow the growth of any existing tumors, according to an American Association for Cancer Research study. Another study, published in Cancer Epidemiology, found that soy-based proteins were particularly effective at warding off breast cancer.
Other foods that help? Plants appear to be a superstar when it comes to lowering the risk of breast cancer. Women who ate high-fiber foods including whole grains and vegetables slashed their risk by about 20 percent, according to research done by the Harvard T. Chan School of Public Health. (Can Fiber Reduce Your Risk of Breast Cancer?) And tomatoes have been singled out for their breast cancer-preventing properties, in a study published in the Journal of Clinical Endocrinology and Metabolism. (See also: These Fruits and Veggies Will Slash Your Risk of Breast Cancer)
On the flip side, sugar has been linked to an increased risk of cancer. "Eating too much sugar increases blood sugar levels, which increases your insulin levels," says Homayoon Sanati, M.D., medical oncologist and medical director of the MemorialCare Breast Center at Orange Coast Memorial Medical Center in California. "Some cancer cells have 'insulin growth factor receptors,' which means that extra insulin can promote their growth."
We can't say that a specific food causes or prevents breast cancer—likely because cancer doesn't seem to have a single, discrete cause—but your diet can impact your risk of getting the disease, Dr. Sanati says. And even if eating all the fruits, veggies, protein, and whole grains in the world don't keep you from getting breast cancer, your diet can certainly affect how equipped your body is to fight it, he adds. Cancer treatments are hard on the body, and a poor diet has been shown to weaken the immune system further, he adds.