Association of a low-inflammatory diet with survival among adults: The role of cardiometabolic diseases and lifestyle.

Background & Aims: Evidence on the association between dietary inflammation and longevity is limited. We aimed to examine the association of a low-inflammatory diet with mortality and longevity, and to explore whether cardiometabolic diseases (CMDs) and lifestyle factors may play a role in this association.

Methods: Within the UK Biobank, 188,443 participants aged 39-72 years (mean 56.07) were followed for up to 16 years to detect survival status from the death registry. At baseline, dietary intake was assessed with a 24-h dietary record. An inflammatory diet index (IDI) was calculated as weighted sum of 31 food groups (including 14 anti-inflammatory and 17 pro-inflammatory) based on plasma high-sensitivity C-reactive protein levels, and tertiled as low, moderate, and high IDI scores. Baseline lifestyle beyond diet was assessed by summing the number of healthy lifestyle factors (i.e., never smoking, regular physical activity, and normal BMI) and categorized as unfavorable (≤1) and favorable (≥2). Presence of CMDs was defined as having any one of type 2 diabetes, ischemic heart disease, atrial fibrillation, heart failure, and stroke. Data were analyzed using Cox regression, Laplace regression, and generalized structural equation modelling.

Results: During the follow-up (median 9.79 years, interquartile range: 9.68-10.57 years), 9178 (4.9%) participants died. In multi-adjusted Cox regression models, a low-inflammatory diet (i.e. low IDI score) was associated with lower risk of all-cause mortality [hazard ratio (HR) = 0.82, 95% confidence interval (CI): 0.78 to 0.86]. Laplace regression analysis showed that the multi-adjusted 10th percentile difference (10th PD, 95% CI) of death time was delayed by 0.80 (0.55, 1.06; P < 0.001) years for participants with a low IDI score compared to those with a high IDI score. In mediation analysis, 21.48% of the association between IDI and mortality was mediated by CMDs. In joint effect analysis, participants with a low IDI score and favorable lifestyle had a 42% lower risk of death (HR = 0.58, 95% CI: 0.54, 0.62) compared to those with a high IDI score and unfavorable lifestyle. There was a significant additive interaction between low IDI score and favorable lifestyle on decreased mortality.

Conclusions: A low-inflammatory diet is associated with a lower risk of death and could prolong survival time. CMDs may partially mediate the IDI-mortality association. A favorable lifestyle beyond diet may augment the positive effect of a low-inflammatory diet on longevity.