A new analysis of data combined from 10 previous studies has concluded that dietary fiber intake is associated with lower risk of breast cancer. Results of retrospective studies (in which women are asked to recall their diets after already having received a diagnosis of breast cancer) and other studies suggest that dietary fiber may reduce breast cancer risk, but the findings are inconclusive. In the current analysis, only prospective studies that assessed diet before any diagnosis of breast cancer were included. The authors identified relevant studies by searching the PubMed database through January 2011. The 10 studies that met the criteria for the meta-analysis had 712,195 participants in total, including 16,848 breast cancer cases.

Women with the highest levels of dietary fiber intake were found to have an 11% lower risk of breast cancer than those with the lowest intake. The results did not vary significantly when the data was divided and analyzed according to geographic region, length of follow-up, or menopausal status of the study participants. Omission of any single study did not significantly change the combined results. Every 10g per day increase in dietary fiber intake was associated with a 7% reduction in breast cancer risk, according to dose-response analysis. The authors conclude that the meta-analysis provides evidence of a significant inverse dose-response association between dietary fiber intake and risk of breast cancer.