A large study found that higher blood levels of the compound genistein (pronounced jenn-is-stine) seems to be linked to a lower risk of breast cancer. Genistein is a plant isoflavone. Isoflavones are found in soybeans and chick peas.
More than 24,000 Japanese women were followed for about 10 years. The women with the highest blood levels of genistein were 65% less likely to develop breast cancer compared to the women with the lowest blood levels of genistein.
It's hard to interpret research on diet and breast cancer risk. This is because the research usually asks people to recall what they ate for a certain period of time. People often don't remember what they've eaten or may be uncomfortable reporting that they ate an entire bag of cookies or a pint of ice cream. The study reviewed here is unique -- instead of asking women what they ate, the researchers simply measured genistein levels.
The researchers aren't sure how genistein might lower breast cancer risk. Genistein and estrogen have similar chemical makeups. So the researchers think that genistein might sit in the estrogen receptors on breast cells and block the cancer-promoting effects of estrogen made by your body. This is how tamoxifen works to lower breast cancer risk and the risk of breast cancer coming back.
The researchers aren't sure if these results will apply to women in Western countries, such as the United States. Japanese women usually eat soybeans and chick peas throughout their lives, starting as young children. Most women in Western countries don't eat soybeans or chickpeas until they're adults. A 2006 research study found that eating soy regularly as a young girl may help protect against the development of breast cancer later on in life.
No food or diet can prevent you from getting breast cancer. But some foods can make your body the healthiest it can be, boost your immune system, and help keep your risk for breast cancer as low as possible. If you think you'd like to change your diet to include more fruits and vegetables, you may want to talk to a registered dietitian about how to create a healthy diet plan that is right for you. Visit the breastcancer.org Nutrition section to learn more about healthy eating and balancing your diet.