Up until now, there have been inconclusive results regarding the association between fiber consumption and the risk of breast cancer. In order to come to a final conclusion, researchers from the Harvard T.H. Chan School of Public Health conducted a systematic review and meta‐analysis of all relevant prospective studies on the topic published before August 2019. Their findings are published in the peer-reviewed journal of the American Cancer Society (ACS), Cancer.
According to their analysis, high-fiber intake is in fact linked with a reduced incidence of breast cancer. The analysis considered data from 20 observational studies, from which they were able to identify that individuals with the highest consumption of fiber had an eight percent lower risk of breast cancer.
The researchers gather data from the MEDLINE and Excerpta Medica dataBASE (EMBASE) databases. From these databases, the authors identified 17 cohort studies, 2 nested case‐control studies, and 1 clinical trial study, with which they conducted their analysis.
Their analysis considered not only the total intake of fiber consumed but also the types of fiber. From this information, they found that soluble fiber, in particular, was associated with lower risks of breast cancer. Notedly, this finding was the same for women with premenopausal and postmenopausal breast cancer.
"Our study contributes to the evidence that lifestyle factors, such as modifiable dietary practices, may affect breast cancer risk," said Dr. Maryam Farvid, who led the research. "Our findings provide research evidence supporting the American Cancer Society dietary guidelines, emphasizing the importance of a diet rich in fiber, including fruits, vegetables, and whole grains."
Nevertheless, the researchers caution that the studies they analyzed were observational studies, meaning they only demonstrate the associations between consumption of fiber and breast cancer risk, not a direct cause. In order to establish direct cause, they say, a randomized clinical trial would be necessary.