Dietary fiber intake is associated with a reduced risk of ovarian cancer: a dose-response meta-analysis

Dietary fiber may reduce the bioavailability of steroid hormones and favorably regulate insulin-like growth factor 1, and therefore may be associated with ovarian cancer risk. Current evidence on the association between dietary fiber intake and risk of ovarian cancer is inconsistent. Therefore, we conducted a meta-analysis to explore the association. We hypothesized that dietary fiber intake might be associated with a reduced risk of ovarian cancer. PubMed, Web of Science, Embase, China National Knowledge Infrastructure, and Wanfang databases were searched for relevant articles up to September 2017. Summary relative risks (RRs) with 95% confidence intervals (CIs) were calculated using random-effects model. Dose-response relationship was assessed by restricted cubic spline. A total of 19 studies involving 567 742 participants were included in this meta-analysis. The summary RR of the association between dietary fiber intake and ovarian cancer risk was 0.70 (95% CI, 0.57-0.87; I2 = 83.5%, Pheterogeneity < .001). In subgroup analyses, the above-mentioned significant inverse association was found among studies conducted in North America, case-control studies, and studies assessing the association of total fiber intake with ovarian cancer risk. Dose-response analysis suggested that ovarian cancer risk decreased by 3% (RR, 0.97; 95% CI, 0.95-0.99) for each 5-g/d increment in dietary fiber intake. This meta-analysis suggests that dietary fiber intake is associated with a reduced risk of ovarian cancer. Future intervention trials are needed to test the associations between different types of fiber (including soluble, insoluble, vegetable, fruit, cereal, and legumes fiber) and ovarian cancer risk.