Here’s the latest on some still uncertain links between diet and breast cancer. Fruits & Vegetables. Several studies have reported that women who consume more fruits and vegetables, especially ones that are rich in carotenoids like beta-carotene, have a reduced risk of postmenopausal breast cancer, especially for estrogen-receptor negative disease. Researchers know less about tumors that are fueled by estrogen. Estrogen-negative breast cancer is more lethal than estrogen- positive cancer and less is know about preventing it. Fruits and vegetables have a pretty small impact overall on cancer, but in this case there may be some benefit. So, any lifestyle changes that reduce the risk of breast cancer would be very beneficial. Vitamin D. Early evidence had suggested that women with blood levels of Vitamin D have a lower risk of breast cancer, but the picture is muddy. Researchers are presently analyzing vitamin D for 24,000 women from 17 cohorts around the world. This should help tell scientists whether the blood levels that people currently attain from sunlight, food, and supplements protect against cancer. Meanwhile, the VITamin D and OmegA-3 TriaL (VITAL) at Brigham and Women’s Hospital, an affiliate of Harvard Medical School, in Boston, Massachusetts, is an ongoing research study in 25,875 men and women across the United States. VITAL is investigating whether taking daily dietary supplements of vitamin D3 (2000 IU) or omega-3 fatty acids (Omacor® fish oil, 1 gram) reduces the risk for developing cancer, heart disease, and stroke in people who do not have a prior history of these illnesses. This study should help clear up whether high doses reduce risk.
- Over the years, the pendulum has swung from seeing soy as a food that prevents cancer to seeing it as one that promotes breast cancer. The challenge for scientists is it is difficult to look at soy well in studies of U.S. women, because they don’t consume enough.
For example, the ten studies that tracked 250,000 U.S. and European women for two to thirteen years, those women who got the most soy isoflavones from food were no more or less likely to be diagnosed with breast cancer than those who got the least. On the other hand, soy foods do seem to protect Asian women. In four studies that tracked more than 130,000 women in Japan, China, and Singapore for seven to eleven years, those women who got the most isoflavones from their food were twenty percent less likely to be diagnosed with breast cancer than those who got the least. The bottom line, the evidence shows that soy foods don’t seem to increase or decrease the risk of breast cancer in Western women. Meat or saturated fat. Some studies have reported a higher risk of breast cancer in women who consume more saturated fat. But the effect of saturated fat during midlife or later is weak, if it’s there at all. However, a meat-heavy diet may boost risk, especially if it is eaten in early adulthood. When researchers take a look at diets earlier in life, when the breast is more susceptible, there has been some increase in the risk in pre-menopausal breast cancer with red meat. It isn’t clear why, but researchers suspect it is something in the red meat other than the fat. However, heme iron or carcinogens that are created when meat is cooked doesn’t seem to explain the risk.