Comparison of diet quality indices for predicting metabolic syndrome in Iran: cross-sectional findings from the persian cohort study.

Background: The metabolic syndrome (MetS) comprises metabolic irregularities, including hypertension and central obesity, which are influenced by genetic, metabolic, environmental, and dietary factors. As diet and lifestyle are risk factors for MetS, it is important to know which diet quality index better predicts MetS. The aim of this study is to compare the ability of different diet quality indices in predicting MetS and to identify the most effective one.

Methods: This cross-sectional study involved 5,206 participants aged 35 to 70 engaged in the Prospective Epidemiological Research Study in Iran (PERSIAN) cohort. Assessment of one year's food intake via a validated 134-item semi-quantitative food frequency questionnaire (FFQ) facilitated the calculation of adherence to five diet quality indices: Dietary Approaches to Stop Hypertension (DASH), Mediterranean, Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND), Dietary Inflammatory Index (DII), and Diet Quality Indices (DQI). While bivariate Pearson correlation and binary logistic regression aided in identifying the strongest correlation and predictor for MetS among the indices.

Results: This study showed a significant association between adhering to the DASH diet score, Mediterranean diet score, MIND diet score, DII score, and DQI score, and the odds of developing MetS (OR: 0.94, (95% CI: 0.93-0.95), OR: 0.85, (95% CI: 0.81-0.89), OR: 0.84, (95% CI: 0.80-0.89), OR: 1.22, (95%CI: 1.11-1.34), OR: 0.95, (95%CI 0.94-0.96) respectively). Therefore, with each unit increase in DASH diet score, Mediterranean diet score, MIND diet score, DII score, and DQI score, the odds of MetS was reduced by 5.4%, 14.5%, 15.6%, 22%, 5%, respectively. All the indices were correlated with the intake of most of the micronutrients, with the strongest correlations being observed in the DII. DASH diet score aligned with the most favourable MetS biomarker risk, while DII score primarily associated with MetS and could be considered as a predictor for MetS.

Conclusion: The present study's findings reveal that between all these five diet quality indices, the DASH diet score correlates strongly with a favourable biomarker risk profile, while the DII score is predominantly linked to MetS.