Women who eat a fiber-rich diet plentiful in foods such as fruits, beans, grains and veggies appear to benefit from a slight reduction in their risk for breast cancer, according to U.S. News and World Report.

Previous studies have found that high-fiber diets have been found to reduce the risk not only for breast cancer but also colorectal, lung and liver cancer.

Publishing their findings in the journal Cancer, Maryam Farvid, PhD, of the Harvard T.H. Chan School of Public Health, and colleagues reviewed data from 20 prospective trials that between them included millions of women.

A prospective study follows participants over time. This method is considered to yield more reliable findings than studies that look back in time to analyze such associations. Combining data from similar studies can also increase the statistical power of the findings.  

Farvid and her colleagues found that women who consumed a high amount of fiber had an 8% lower risk of breast cancer compared with women who consumed low amounts of fiber. Such a fiber-related risk reduction applied to both pre- and postmenopausal women. It also applied to various subtypes of breast cancer.

How might fiber reduce breast cancer risk? Scientists believe that fiber helps decrease insulin and other growth factors circulating in the blood and also lowers estrogen levels; all these factors can drive breast cancer development.

The study found a non–statistically significant suggestion that insoluble fiber, the kind that predominates in grains, reduced risk, as well as a statistically significant indication that soluble fiber, found in beans and oats and nuts, reduced risk.

Overall, these findings add up to a simple message: Eat more fiber-rich, plant-based foods from any source.

“The reduction in risk appears to be similar for intake of all sources of fiber,” Farvid’s group wrote.

What mattered was that women consumed a sufficient amount of fiber, whether through beans or whole grains, veggies or fruits.

The study’s findings back up the American Cancer Society dietary guidelines to eat fiber-rich foods.

To read the U.S. News and World Report article, click here.

To read the study abstract, click here.

To learn more about diet and breast cancer, see “A Low-Fat, Plant-Based Diet Cuts the Risk of Dying of Breast Cancer.”