Sex differences in the effects of dietary fiber on chronic disease risk: a meta-analysis of prospective cohort studies

Abstract Dietary fiber plays a key role in preventing chronic diseases, but sex disparities in its health effects remain unclear. This meta-analysis examined the associations between fiber intake and chronic disease risk in men and women; cohort studies reported on in published articles found in the PubMed, Web of Science, and Embase databases were reviewed up to July 2025. Among 2 408 576 participants (n = 1 035 449 men and 1 392 820 women) from 20 studies, higher fiber intake was linked to reduced chronic disease risk in both sexes, with a pooled hazard ratio (HR) of 0.80 (95% CI, 0.75-0.84) for men and 0.83 (95% CI, 0.76-0.91) for women. Notably, fiber significantly lowered cancer risk only in men (HR = 0.81; 95% CI, 0.75-0.87). Grains and vegetable fiber reduced chronic disease risk in men (HR = 0.90 and 0.86, respectively), whereas no specific fiber source had significant benefits for women. In conclusion, although dietary fiber significantly reduced the risk of chronic diseases for both sexes, the threshold for observing beneficial effects is lower in men compared with women, in whom its impact may be more susceptible to confounding factors. More research is needed to clarify sex-specific dietary recommendations for chronic disease prevention.