Beans May Reduce Breast Cancer Risk

Study: Beans may reduce breast cancer risk

Beans, beans, they’re good for the heart… and the breasts? Maybe so, according to two studies in the International Journal of Cancer that deal with how beans and other foods can affect your breast cancer risk.

The first study investigated the link between consumption of flavonols – substances in plant-based foods that are thought to offer protection against a variety of diseases – and the risk of developing breast cancer in premenopausal women.

Researchers at the Harvard School of Public Health in Boston, Massachusetts, analyzed data from more than 90,000 premenopausal women who participated in the Nurses Health Study II. Using information on the women’s diets gleaned from food frequency questionnaires, the researchers compared the women’s intake of a variety of flavonols with their chance of developing breast cancer. Over the course of the study, 710 of the women were diagnosed with breast cancer.

While the researchers found no association between breast cancer risk and consumption of the types of flavonols contained in tea, onions, apples, string beans, broccoli, green peppers, and blueberries, they found that women who ate beans and lentils on a regular basis were less likely to develop breast cancer. In fact, they found that women who ate beans or lentils at least twice a week were 24% less likely to develop breast cancer than women who ate those foods less than once a month.

The second study examined the link between breast cancer risk and glycemic index in the diet. A food’s glycemic index value is a ranking of the effect of its carbohydrates on blood sugar levels. Foods with high glycemic index values cause a quick rise in blood sugar, whereas low-glycemic-index foods raise blood sugar more slowly.

In the study, a team of researchers looked at the overall glycemic index and other factors in the diets of nearly 50,000 Canadian women who had participated in the National Breast Cancer Screening Study. During a follow-up period of 16 years, 1,461 women developed breast cancer.

While the researchers found no link between glycemic index and breast cancer risk in the overall study population, in postmenopausal women, they found diets with a high glycemic index were associated with an 87% greater risk of breast cancer. The association was even stronger among postmenopausal women who reported no vigorous physical activity, those who had been treated with hormone replacement therapy and women who were not overweight.

There are many factors that can affect a food’s glycemic index, including how processed it is and how it is prepared. Generally, wholesome, high-fibre foods such as whole grains, legumes, beans, fruits and vegetables tend to have better glycemic ratings than most starchy or processed foods.

In premenopausal women, a high glycemic-index diet was actually associated with a 22% reduction in breast cancer risk.

Both studies note that further investigation must be done before any broad conclusions may be drawn.