Eating a diet rich in fruits and vegetables can reduce the risk of breast cancer, finds a study led by researchers from Harvard T.H. Chan School of Public Health.

The study found cruciferous vegetables such as broccoli, and yellow and orange vegetables, had a particularly significant association with lower breast cancer risk. "Although prior studies have suggested an association, they have been limited in power, particularly for specific fruits and vegetables and aggressive subtypes of breast cancer," said first author Maryam Farvid.

"This research provides the most complete picture of the importance of consuming high amounts of fruit and vegetables for breast cancer prevention." The researchers found that women who ate more than 5.5 servings of fruits and vegetables each day had an 11 percent lower risk of breast cancer than those who ate 2.5 or fewer servings. (A serving is defined as one cup of raw leafy vegetables, half a cup of raw or cooked vegetables, or half a cup of chopped or cooked fruits.)

To find out whether the benefits of fruit and vegetable consumption differed among various types of breast cancers, the researchers conducted an analysis by tumor hormone receptor status and molecular subtype. They found that higher consumption of fruits and vegetables was particularly associated with lower risk of more aggressive tumors including ER-negative, HER2-enriched, and basal-like tumors.

"While a diet with lots of fruits and vegetables is associated with many other health benefits, our results may provide further impetus for women to increase their intake of fruits and vegetables," said senior author Heather Eliassen. The study has been published in the International Journal of Cancer.