Association between nut consumption and mortality risk: a 20-year cohort study in Korea with a stratified analysis by health-related variables.

Background: Although nuts are a well-known healthy food group, the relationship between nut consumption and mortality remains unclear, particularly among Asians. This prospective cohort study examined the association between nut consumption and the risk of all-cause, cardiovascular disease (CVD), and cancer mortality in Korean adults.

Methods: Data from two cohorts (the Ansan-Ansung and Health-Examinees) from the Korean Genome and Epidemiology Study were used. A total of 114,140 individuals aged 40-79 years were included in the data analyses. Nut consumption was assessed using a validated semi-quantitative food frequency questionnaire and categorized into four groups: non-consumers, less than 1 serving/week, 1-2 servings/week, and 2 or more servings/week (one serving was 15 g of nuts). Mortality outcomes were determined based on the 2001-2021 death records from Statistics Korea. Cox proportional hazard regression analysis was used to calculate hazard ratios (HRs) and 95% confidence intervals (CIs) for mortality across nut consumption categories. A stratified subgroup analysis by health-related variables was also performed.

Results: During a mean follow-up of 12.3 years, 4,559 deaths were recorded. After adjusting for covariates, the HR for all-cause mortality was 0.877 (95% CI = 0.772-0.996, p for trend = 0.006) in individuals with a nut consumption of 2 or more servings/week compared with that in non-consumers. Multivariable HRs for CVD mortality were 0.800 (95% CI = 0.681-0.939) in individuals consuming less than 1 serving/week, 0.656 (95% CI = 0.469-0.918) in those consuming 1-2 servings/week, and 1.009 (95% CI = 0.756-1.347) in those consuming 2 or more servings/week compared with that in non-consumers (p for trend = 0.080). No association was observed between nut consumption and cancer mortality. Stratified analysis identified significant interactions in the association between nut consumption and all-cause mortality by age, body mass index, and physical activity.

Conclusions: Nut consumption was linearly associated with the reduced risk of all-cause mortality and showed a non-linear dose-response relationship with CVD mortality in Koreans, but had no association with cancer mortality. The effects of nut consumption, which have been inadequately investigated in this population, varied across different subgroups. These findings suggest that incorporating nuts into the diet should be encouraged for long-term health of Korean adults.