Metabolic & Cardiometabolic
PCOS decreases gut microbiome diversity
Part of: • PCOS
📅 Last reviewed: 2026-07-15 ⓘ
Evidence ladder
How far up the ladder this claim has climbed. A high consensus on a low rung means "consistent so far," not "proven in people."
Top evidence so far: All trials, pooled (Meta-analysis)
How the studies fall
What the evidence shows
PCOS reduces gut-microbiome alpha-diversity.
The evidence (7)
| Source | Grade | Stance | Quality | Finding |
|---|---|---|---|---|
| Kaliappa GD, Palanisamy H, Vidyalakshmi S 2026 · F&S science | observational | mixed | moderate | Case-control metagenomics: PCOS showed 'marked gut microbial dysbiosis' by alpha/beta diversity yet 'comparable species richness' to controls vs healthy age-matched women. |
| Chen K, Geng H, Ye C, Liu J 2024 · Microbiol Spectr | observational | supports | low | PCOS women had reduced gut microbiota diversity and richness vs healthy controls |
| Zou Y, Liao R, Cheng R, Chung H, Zhu H, Huang Y 2023 · Microb Pathog | meta-analysis | supports | moderate | Meta-analysis of 19 observational studies (617 PCOS, 439 controls): 'the Chao index (WMD -28.88, 95% CI -45.78 to -11.98, I2 = 100%), Shannon index (WMD -0.11, 95% CI -0.18 to 0.00, I2 = 92.2%); and observed operational taxonomic units (OTUs) counts (WMD - 23.48, 95% CI -34.44 to -12. 53, I2 = 99.6%) were significantly lower in women with PCOS.' Direction supports reduced alpha diversity; extreme heterogeneity makes the size unreliable and Shannon's interval reaches 0.00. The earlier 'minimal/inconsistent' reading came from the Background sentence about a prior summary, not from this paper's results. |
| Chen Z, Lu Q, Lin A, Tan M, Li W, Tang S, Feng J, Hou C, Zhu Y, Xu M, Liu T, Xia M 2025 · Sci Rep | animal | contradicts | low | DHEA-induced PCOS rats showed INCREASED alpha/beta diversity, conflicting with reduced-diversity claim |
| Yang T, Li G, Xu Y, He X, Song B, Cao Y 2024 · BMC Microbiol | observational | contradicts | low | 16S V3-V4 case-control (PCOS n=18 vs healthy n=16, plus PCOS+dyslipidemia n=18; age- and BMI-matched): 'Furthermore, the α diversity of patients with PCOS was increased than that of controls. However, no significant differences between the Control and PCOS.D or between the PCOS and PCOS.D groups were observed', and 'Our results showed that the β diversity of gut microbiota did not differ significantly among the three groups.' Alpha diversity moved OPPOSITE to the claim in the PCOS vs Control contrast and was null in the PCOS.D vs Control contrast. |
| solaleyva-2023 2023 · Reproductive biomedicine online | meta-analysis | supports | moderate | Alpha-diversity SMD -0.20 (small; high RoB). |
| Li YM, He FF, Donge-Liu, Bin-Xu, Shuyi-Li 2026 · Health science reports | observational | contradicts | moderate | 16S reanalysis (PCOS n=24 vs HC n=12) + public data (PCOS n=98 vs HC n=71), all normal-weight: 'no significant differences in beta and alpha diversity between PCOS and normal controls.' |
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