Dietary inflammatory index and mortality: a cohort longitudinal study in a Mediterranean area

Background: Higher Dietary Inflammatory Index (DII®) scores are associated with increased morbidity and mortality. However, little is known about the effects of DII on mortality in Mediterranean countries. Therefore, in the present study, we aimed to investigate the potential association between DII scores and overall, cancer and cardiovascular disease (CVD) mortality in people living in a Mediterranean area.

Methods: DII scores were calculated using a validated food-frequency questionnaire. DII scores were then categorised into tertiles. Mortality was ascertained via death certificates. The association between DII scores with overall and cause-specific mortality was assessed via a multivariable Cox's regression analysis and reported as hazard ratios (HRs) with their 95% confidence intervals (CIs).

Results: The study included 1565 participants (mean age 65.5 years; females 44.7%). After a median follow-up of 12 years (2005-2017), 366 (23.4%) participants died. After adjusting for 17 potential confounders, people with higher DII scores had an increased risk of death compared to those in the lowest (most anti-inflammatory) tertile (HR = 1.38; 95% CI = 1.04-1.82 for the second tertile; HR = 1.38; 95% CI = 1.03-1.86 for the third tertile). Each 1 SD increase in DII score increased the risk of death by 13%. No association was found between DII scores and cancer or CVD death when considered separately.

Conclusions: Higher DII scores were associated with a significantly higher mortality risk, whereas the association with cause-specific mortality was less clear. These findings highlight the potential importance of diet in modulating inflammation and preventing death.