High dietary fibre intake has been associated with reduced breast cancer risk.
However, few studies have explored the impact by breast cancer tumour subtypes or by racial/ethnic groups, who vary in their fibre intake.
In a study conducted by the Cancer Prevention Institute of California, and published ahead of print in Cancer Medicine, researchers compared women with breast cancer to women without breast cancer and found overall breast cancer risk was reduced by 25% with a high intake of bean fibre, total beans, or total grains.
Greater reductions in risk ranging from 28 to 36% were found for women with estrogen receptor and progesterone receptor negative (ER-PR-) breast cancers in comparison to women with receptor positive breast cancer.
For bean fibre, risk of ER-PR- disease was reduced among foreign-born Hispanics only, who had the highest fibre intake, and consumed the largest proportion of fibre from beans.
Researchers did not find fibre intake from fruits and vegetables to reduce breast cancer risk.
For U.S.-born Hispanics, African Americans and whites, fruits and vegetables were the primary source of fibre intake.
High grain intake reduced risk of ER-PR- breast cancer among white women only.
A large proportion of the study participants did not meet the recommendations for daily fibre intake.
African Americans consumed the least fibre amount of fibre of the three racial/ethnic groups studied.
To conduct this study researchers gathered information on fibre intake from 2,135 women diagnosed with breast cancer participating in the San Francisco Bay Area Breast Cancer Study, a population-based study, and 2,571 women without breast cancer.
According to Esther John, the senior researcher of the study, “Most currently known risk factors for breast cancer apply to hormone receptor positive subtypes. This paper adds to the evidence that dietary factors may play a role in ER-PR- breast cancer which is more frequently diagnosed in African American and Hispanic women.”