Effects of healthy lifestyles on the association between food security and all-cause mortality risk

Food insecurity is associated with increased mortality risk, but whether this association is modified by lifestyle behaviors in the general adult population remains unclear. We analyzed seven NHANES cycles (2005–2018) including 41,161 adults (≥ 18 years). Food security was categorized per USDA guidelines. Four lifestyle factors—smoking status, alcohol consumption, physical activity, and sleep duration (< 6.5, 6.5-<7.5, or ≥ 7.5 h/night)—were assessed via standardized questionnaires, and a healthy lifestyle score (0–4) was constructed by summing these four components. All-cause mortality was determined through linkage to the National Death Index through December 31, 2019. We used Cox proportional hazards models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for all-cause mortality across food security categories and by healthy lifestyle score, adjusting for demographic and socioeconomic characteristics, health status indicators (BMI, history of diabetes, hypertension, hypercholesterolemia, and health insurance coverage), and dietary factors (total daily energy intake and overall diet quality). We conducted prespecified subgroup analyses by age (< 65 vs. ≥ 65 years), sex, and health insurance status, and performed sensitivity analyses. During 204,944 person-years of follow-up, 2835 total deaths occurred. Food insecurity was associated with higher all-cause mortality (HR 1.85 [95% CI, 1.60–2.14]; P < 0.001). In joint analyses restricted to food-insecure adults, compared with those with the most unfavorable behaviors, participants who never smoked had a 51% lower hazard of mortality (HR, 0.49 [95% CI, 0.39–0.61]), those who never drank alcohol had a 27% lower hazard (HR, 0.73 [95% CI, 0.56–0.97]), those with moderate/regular physical activity had a 32% lower hazard (HR, 0.68 [95% CI, 0.49–0.96]), and those reporting sleep duration of 6.5-<7.5 h/night had a 26% lower hazard (HR, 0.74 [95% CI, 0.55–0.98]). The healthy lifestyle score showed a graded inverse association, among food-insecure adults, having 3–4 versus 0 healthy behaviors was associated with a 61% lower hazard of death (HR, 0.39 [95% CI, 0.23–0.66]). Associations were stronger among participants aged < 65 years and were robust in sensitivity analyses. Food insecurity is significantly associated with higher all-cause mortality risk, while healthy lifestyle behaviors can effectively buffer this risk, especially in food-insecure adults.