Lower Fiber Consumption in Women with Polycystic Ovary Syndrome: A Meta-Analysis of Observational Studies

Polycystic ovary syndrome is a common endocrine disorder associated with metabolic abnormalities and gut microbiota dysbiosis. The deficiency of dietary fiber, a crucial nutrient in the daily diet, is also associated with a wide range of metabolic and reproductive abnormalities, as well as an altered gut microbial ecosystem. This study is a meta-analysis to summarize the available evidence on the dietary fiber intake level in PCOS patients. Databases of PubMed, Embase, Cochrane Library, Web of Science, and ClinicalTrials.gov were searched for observational studies, and 13 studies were finally included. The pooled standardized mean difference (SMD) with the 95% confidence interval (CI) of daily dietary fiber intake and total energy intake were calculated using the random-effects model. The pooled result (12 studies) on absolute dietary fiber intake showed that while there was no significant difference in the total energy intake [−0.17 (−0.44, 0.09), p = 0.208], the dietary fiber intake was significantly lower in PCOS women than those of controls [−0.32 (−0.50, −0.14), p < 0.001]. However, significant heterogeneity was detected across the studies (I(2) = 65.6%, p = 0.001). Meta-regression suggested that geographic region and dietary assessment method may confer borderline significance of influence on the heterogeneity. The pooled result (two studies) on dietary fiber intake which adjusted for total energy intake, however, showed no significant difference [−2.11 (−4.77, 0.56), p = 0.122]. In subgroup analyses based on absolute dietary fiber intake, a lower dietary fiber intake in PCOS was observed in studies conducted in Asia, adopted food diary or records or food recall as the dietary assessment method, had a case–control study design, or used Rotterdam criteria for PCOS diagnosis. The difference in SMD was still significant in the adult subgroup or in studies matched or unmatched for age.