New US research has found that women who eat at least five and a half portions of fruit and vegetables every day may have a lower risk of breast cancer, especially aggressive tumours, than those who have a lower daily intake.
Led by researchers from Harvard T.H. Chan School of Public Health, the large-scale study looked at 182,145 women aged 27 to 59 years taking part in the long-term Nurses’ Health Study and Nurses’ Health Study II, two of the largest investigations looking into women’s risk factors for major chronic diseases.
The researchers analyzed diet questionnaires submitted by the women every four years, as well as data provided on other potential breast cancer risk factors such as age, weight, smoking status, and family cancer history.
The results showed 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 was 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.
In particular cruciferous vegetables such as broccoli and yellow and orange vegetables were found to have a particularly significant association with lower breast cancer risk.
The team also studied whether fruit and vegetable consumption affected various types of breast cancers differently, finding that higher consumption of fruits and vegetables appeared to be particularly beneficial for lowering the risk of more aggressive tumors including ER-negative, HER2-enriched, and basal-like tumors.
“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,” commented 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.”
Previous work by the same researchers found that a higher intake of fiber is linked with a reduced risk of breast cancer. But the benefits of fruits and vegetables found in this study appeared to be independent of their fiber content, suggesting that other components, such as antioxidants and other micronutrients, may also be important in reducing breast cancer risk.
“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 results were published online in the International Journal of Cancer.