Lower Fiber Consumption in Women with Polycystic Ovary Syndrome Original paper

What was reviewed?

This meta-analysis synthesized data from 13 observational studies to evaluate whether women with polycystic ovary syndrome (PCOS) consume significantly less dietary fiber than women without PCOS. The analysis sought to determine if reduced fiber intake is an overlooked factor contributing to the metabolic and endocrine dysfunction commonly seen in PCOS. Additionally, the review assessed whether total caloric intake differed between groups and explored how geographic location, dietary assessment methods, and body mass index (BMI) might influence findings. The research incorporated studies conducted across Asia, Europe, North America, and South America, using diverse methodologies such as food diaries, recalls, and food frequency questionnaires (FFQs).

Who was reviewed?

The included studies encompassed a total of 2,469 women, 1,130 with PCOS and 1,339 controls. Participants spanned diverse age groups (adolescent and adult women) and body weight categories (lean and overweight/obese). Most studies used the Rotterdam criteria for PCOS diagnosis. Dietary fiber intake data were extracted using self-reported dietary tools over periods ranging from 1 to 7 days. Nine of the thirteen studies were deemed high quality using the Newcastle–Ottawa Scale. The meta-analysis particularly emphasized studies not adjusted for total energy intake, although two studies did include such adjustments.

What were the most important findings?

The pooled analysis revealed that women with PCOS had significantly lower absolute dietary fiber intake compared to controls, despite no significant difference in total caloric intake. This suggests that the reduction in fiber is independent of overall energy consumption and reflects a dietary quality issue rather than quantity. Subgroup analysis confirmed that this difference persisted across various continents, dietary methods (especially food recall and diary), and study designs (notably case–control). Importantly, the difference was also maintained in adult populations and studies using the Rotterdam criteria for diagnosis.

Though the meta-analysis did not directly assess microbiome composition, the findings carry strong implications. Fiber is a critical prebiotic nutrient known to foster the growth of beneficial microbial taxa such as Faecalibacterium prausnitzii, Bifidobacterium spp., and Lactobacillus spp. These microbes produce short-chain fatty acids—notably butyrate—that regulate systemic inflammation, insulin sensitivity, gut barrier integrity, and even reproductive hormone modulation. A diet deficient in fiber diminishes SCFA production, reduces microbial diversity, and allows expansion of pro-inflammatory taxa like Collinsella and Proteobacteria. These alterations are well aligned with the dysbiosis commonly documented in PCOS, suggesting that low fiber intake may be both a symptom and driver of gut microbiota imbalance in this population.

What are the greatest implications of this review?

This meta-analysis establishes that reduced dietary fiber intake is a consistent dietary pattern in women with PCOS, regardless of caloric intake or body weight. The findings reinforce the need for clinicians to go beyond calorie counting and assess the qualitative aspects of dietary intake, particularly fiber. Given fiber’s central role in modulating the gut microbiome and producing SCFAs, inadequate intake could perpetuate insulin resistance, chronic inflammation, and hyperandrogenism in PCOS. These data provide a rationale for integrating dietary fiber intake goals into clinical guidelines for PCOS management. Moreover, the gut–diet–hormone axis illuminated by this review highlights an urgent need for interventional studies targeting fiber intake, either through food-based strategies or supplementation, as a means to correct dysbiosis and metabolic dysfunction in PCOS. Clinicians should consider fiber assessment and counseling as standard practice in the nutritional management of women with PCOS.