Association between the dietary inflammatory index, waist-to-hip ratio and metabolic syndrome.

Inflammation due to poor diet may contribute to the development of metabolic syndrome (MetSyn). The Dietary Inflammatory Index (DII) was created to characterize diet on a scale from anti- to pro-inflammatory. Our hypothesis was that higher (i.e., more pro-inflammatory) DII scores are associated with an increased prevalence of MetSyn compared to those with lower (i.e., more anti-inflammatory) DII scores. Data from the Polish-Norwegian (PONS) Study were analyzed using logistic and linear regression procedures in SAS (version 9.4). Comparisons of interest were between the first and fourth DII quartiles; analyses were stratified by sex. Mean waist-to-hip ratio (WHR) and diastolic blood pressure were greater among those in DII quartile 4 compared to 1. No statistically significantly increased MetSyn risks were observed for DII quartile 4 among men or women. Men in DII quartile 4 had elevated odds of fulfilling the waist component of MetSyn (odds ratio=1.65, 95% confidence interval=1.01-2.69). Although this study benefited from the DII and large sample sizes for both men and women, its cross-sectional nature and use of self-reported data may limit interpretation of results. Further work must be done in longitudinal studies to understand whether pro-inflammatory diets are associated with an increased risk of MetSyn, its components or other metabolic-related conditions. Additionally, further examination of the DII in relation to body habitus will be needed to understand the role of pro-inflammatory diets on anthropometrics, as observed in this study.