Consuming high amount of fruits and vegetables may put women at a lower risk of breast cancer, especially of aggressive tumours, a new study suggests.
The findings suggested that women, among the study participants, who ate more than 5.5 servings of fruits and vegetables each day had an 11 per cent lower risk of breast cancer than those who ate only 2.5 or fewer servings.
The researchers also found that higher consumption of fruits and vegetables was particularly associated with lower risk of more aggressive tumours including ER-negative, HER2-enriched and basal-like tumours.
Cruciferous vegetables such as broccoli, yellow and orange vegetables had a particularly significant association with lower breast cancer risk, suggests the study published in the International Journal of Cancer.
This suggests that other constituents of these foods, such as antioxidants and other micro-nutrients, may also be important in reducing 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 from the Harvard T.H. Chan School of Public Health in Boston.
"This research provides the most complete picture of the importance of consuming high amounts of fruit and vegetables for breast cancer prevention," Farvid added.
For the study, the researchers analysed diet questionnaires submitted every four years by participants in the Nurses' Health Study (88,301 women) and the Nurses' Health Study II (93,844 women).
The researchers also conducted an analysis by tumour hormone receptor status and molecular subtype to find out whether the benefits of fruit and vegetable consumption differed among various types of breast cancers.
A serving was defined as one cup of raw leafy vegetables, half a cup of raw or cooked vegetables or chopped or cooked fruits.
Previous studies have linked higher fiber intake with reduced risk of breast cancer, but the benefits of fruits and vegetables found in this study appear to be independent of their fiber content, the researchers noted.