Food Insecurity, Cardioprotective Diets, and Mortality Among US Adults

Abstract Importance The DASH and Mediterranean diets are cardioprotective. Food insecurity (FI) limits access to healthy food. The relationship between FI, cardioprotective diets, and mortality is unknown. Objective To assess whether adherence to the DASH or Mediterranean diet affects all-cause and cardiovascular mortality independent of food insecurity. Furthermore, to evaluate if enrollment in the Supplemental Nutrition Assistance Program (SNAP) significantly affects diet quality and interacts with the relationship between cardioprotective diet adherence and mortality. Design, Setting, Participants A retrospective cohort study using cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) including study cycles 1999-2018 and longitudinal mortality data from the National Death Index (NDI). NHANES is a weighted population-based study that represents the non-institutionalized civilian population in the United States. Adults age > 18 years with complete food security, dietary recall, and mortality data were included. Exposures Adherence to DASH or Mediterranean diet and food security status. Main outcomes and measures All-cause and cardiovascular disease (CVD) related mortality. Results 51,193 eligible adults were analyzed, representing a weighted population size of 207.1 (200.1 – 214.2) million. Participants with FI were more likely to be younger, female, Black or Hispanic, smokers, obese, lower educational attainment, lower income, and less physically active. FI was a significant predictor of all-cause mortality (p=0.006) but not CVD mortality (p=0.263). After adjustment for multiple covariates and food security status, DASH diet non-adherence significantly predicted all-cause mortality in those with hypertension (p=0.038) and coronary heart disease (CHD) (p=0.001), and CVD mortality in CHD (p=0.041). Mediterranean diet non-adherence significantly predicted all-cause mortality across the entire study population (p=0.005). There was no significant interaction effect between adherence to cardioprotective diets and SNAP enrollment in prediction of all-cause or CVD mortality. Food security was a significant predictor of adherence to the Mediterranean diet (p=0.001). SNAP enrollment was associated with improved adherence to the DASH diet among food insecure individuals (p=0.024), and the Mediterranean diet among food secure individuals (p=0.001). Conclusions and relevance The relationship between FI and mortality is associated with diet quality. Expanding SNAP eligibility to include food security status may have positive effects on public health. Key points Question Does adherence to the DASH or Mediterranean diet decrease all-cause and cardiovascular mortality, and is this related to food insecurity status? Findings Independent of food insecurity, impaired adherence to cardioprotective diets predicted increased risk of all-cause and cardiovascular disease mortality in select patient populations with hypertension or coronary heart disease. SNAP enrollment was not a significant effect modifier in the relationship between mortality and diet adherence, but it did predict increased adherence to the DASH diet in food insecure individuals. Meaning Our results support the hypothesis that mortality in FI is mediated by impaired diet quality.