The dietary inflammatory index and insulin resistance or metabolic syndrome in young adults

The aim of this study was to assess the association between the inflammatory potential of diet, as measured by the dietary inflammatory index (DII) and insulin resistance (IR) or metabolic syndrome (MetS).

A cross-sectional study (nested within a cohort) was conducted on 2017 adults 23 to 25 y of age in Ribeirão Preto, Brazil. Food consumption was assessed using a validated food frequency questionnaire. DII scores were calculated from 35 available food parameters. IR was determined from the classification of homeostatic model assessment (HOMA) values (≥2.7 uU mL-1). MetS was diagnosed based on the Joint Interim Statement (JIS) criterion. The association of DII score with IR or MetS was determined by Poisson regression analysis. The variables included in the multivariable model were selected from directed acyclic graphs.

The diet of the young adults studied showed a high inflammatory potential, with a mean DII score of +1.10 (range: -4.69 to +5.28). The prevalence of MetS was 12.2% and IR 12.3%; both were higher in men than in women. The correlation between DII and HOMA-IR values was -0.038 (P = 0.09). The DII was not associated with IR or MetS in either sex.

Although the association between DII and the outcomes was not detected in this sample, the study demonstrated that the diets of these young adult Brazilians had a high inflammatory potential when compared with other studies. Future studies, preferably using longitudinal designs, are recommended.