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Association between dietary inflammatory index and polycystic ovary syndrome: a meta-analysis of case-control studies

Huang J, Dong C, Qiu D, Li X

Frontiers in endocrinology, 2026

1,554 participants

Abstract

Objective: This study aimed to systematically analyze the association of the dietary inflammatory index (DII) with polycystic ovary syndrome (PCOS) status, thus offering evidence-based support for dietary interventions in the management of PCOS.

Methods: Four databases were systematically searched to collect case-control studies on DII and PCOS published up to December 21, 2025. The Newcastle-Ottawa Scale (NOS) was utilized to assess the risk of bias in the included studies. Using Stata 15.0, we conducted a meta-analysis to compare DII scores in PCOS patients versus those in healthy controls. Subgroup analyses were conducted to identify sources of heterogeneity. An exploratory meta-regression was conducted, but due to the small number of studies, the results could not be interpreted.

Results: Six case-control studies involving 1,554 participants were ultimately included. Meta-analysis revealed slightly but statistically significantly higher DII scores in the PCOS group than in healthy controls (standardized mean difference [SMD]: 0.23; 95% confidence interval [CI]: 0.06-0.40; P = 0.008). Sensitivity analyses suggested robustness of the results. Egger's test showed no statistical evidence of publication bias (P = 0.611); however, with only six studies the statistical power was very low, so publication bias cannot be excluded, and this analysis should be regarded as exploratory.

Conclusion: Pro-inflammatory dietary patterns are modestly associated with PCOS. Although causality…

How strong is the evidence?

Evidence Hub reads this as a meta-analysis, done in people. Its evidence level is 1 of 5 (Highest · pooled evidence). Pooled evidence from several studies sits at the top of the evidence pyramid. Reported size: 1,554 participants or records.

How the five levels of evidence work. The level is assigned automatically from the abstract and can be wrong, so check the paper.

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