Dietary Patterns Modify the Association of Body Mass Index with Mortality in Chinese Community-Dwelling Older Adults

Objectives: Previous studies have shown a J-shaped relationship between body mass index (BMI) and mortality. However, it remains unclear whether dietary patterns modify the nonlinear association between BMI and mortality among older adults. Therefore, we aimed to examine the stratified and combined associations of dietary patterns and BMI with all-cause, cancer, and cardiovascular disease (CVD) mortality in older adults. Methods: This prospective cohort study included 3,982 community-dwelling men and women aged over 65 years at baseline from the Mr. OS and Ms. OS (Hong Kong) study. Dietary patterns were assessed using five indices: Diet Quality Index-International (DQI-I), Dietary Inflammatory Index (DII); Mediterranean Diet Score (MDS), Dietary Approaches to Stop Hypertension score (DASH), and the Mediterranean-DASH Intervention for Neurodegenerative (MIND). Data on mortality were obtained from the Hong Kong Government Death Registry. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). Results: During a median follow-up period of 16.8 years, there were 1,879 all-cause deaths, 561 cancer deaths, and 386 CVD deaths. Higher scores on DQI-I, DASH, MDS, MIND, or lower DII scores attenuated the risks of all-cause and cancer mortality in individuals with low or high BMI. The J-shaped BMI-mortality relationship became less steep when compared with lower scores on these dietary patterns or higher DII scores. Individuals with low DQI-I and underweight had higher risks of all-cause mortality (HR: 1.73, 95% CI: 1.36-2.20), and those with low DQI-I and obesity were also associated with higher risk (HR:1.26, 95% CI: 1.03-1.55), compared with those with high DQI-I and normal weight. For cancer mortality, higher risks were also observed in individuals with low DQI-I and underweight (HR: 1.82, 95% CI: 1.16-2.84) or obesity (HR:1.94, 95% CI: 1.39-2.72). Similar results were found for other dietary patterns. However, no significant interactions were observed between dietary patterns and BMI for CVD mortality. Conclusions: Our findings suggest that healthy diets attenuated the increased risks of all-cause and cancer mortality related to underweight or obesity in older adults. Funding Sources: This study was funded by the National Institutes of Health R01 grant and the Hong Kong Research Grants Council Earmarked grant.