Association between dietary inflammatory index, empirical dietary inflammatory patterns, dietary and lifestyle inflammation scores, and polycystic ovary syndrome: a case-control study.

Background: Polycystic ovary syndrome (PCOS) is a common metabolic and endocrine disorder affecting women of reproductive age. Chronic low-grade inflammation is implicated in its pathogenesis, with diet and lifestyle playing pivotal roles. The Dietary Inflammatory Index (DII), Empirical Dietary Inflammatory Pattern (EDIP), and Dietary and Lifestyle Inflammation Scores (DLIS) are distinct indices developed to assess systemic inflammation. The DII focuses on nutrient composition, EDIP derives from data-driven food patterns, and DLIS integrates both dietary and lifestyle factors. While these inflammatory indices have been linked to metabolic diseases, their associations with PCOS remain unexplored. This study aimed to evaluate these associations.

Methods: This case-control study included 100 women with newly diagnosed PCOS (confirmed by Rotterdam criteria, within 3 months) and 100 age-matched (± 2 years) controls, recruited from the Imam Khomeini Hospital Infertility Centre in Ahvaz, Iran. Controls were selected from women visiting the same center for routine fertility check-ups, excluding those with PCOS symptoms or hormonal disorders. Dietary intake was assessed using a validated 147-item Food Frequency Questionnaire. Inflammatory scores were calculated, and logistic regression was used to analyze their associations with PCOS.

Results: The results showed that the odds of PCOS were higher in the multivariable model across tertiles of DLIS (OR: 3.70; 95%CI: 1.05-5.70, P-trend = 0.002) and DII (OR: 2.82; 95%CI: 1.10-5.60, P-trend = 0.03) after controlling for age, BMI, energy intake (except for DII), physical activity, educational level, marital status, parity, employment status, household income, history of diabetes mellitus, and hypothyroidism. However, no statistical association was found between EDIP and the likelihood of PCOS.

Conclusion: Pro-inflammatory diets (higher DII) and combined diet-lifestyle patterns (higher DLIS) were associated with odds of PCOS, highlighting the importance of anti-inflammatory interventions. However, the case-control design limits causal interpretation, and future cohort studies are needed to confirm temporality.