Association of Walnut Consumption with Total and Cause-Specific Mortality and Life Expectancy in U.S. Adults

Abstract

Walnut consumption is associated with health benefits. We aimed to (1) examine the association between walnut consumption and mortality and (2) estimate life expectancy in relation to walnut consumption in U.S. adults. We included 67,014 women of the Nurses' Health Study (1998-2018) and 26,326 men of the Health Professionals Follow-up Study (1998-2018) who were free of cancer, heart disease, and stroke at baseline. We used Cox regression models to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). During up to 20 years of follow-up, we documented 30,263 deaths. The hazard ratios for total mortality across categories of walnut intake (servings/week), as compared to non-consumers, were 0.95 (95% confidence interval (CI), 0.91, 0.98) for <1 serving/week, 0.94 (95% CI, 0.89, 0.99) for 1 serving/week, 0.87 (95% CI, 0.82, 0.93) for 2-4 servings/week, and 0.86 (95% CI, 0.79, 0.93) for >=5 servings/week (p for trend <0.0001). A greater life expectancy at age 60 (1.30 years in women and 1.26 years in men) was observed among those who consumed walnuts more than 5 servings/week compared to non-consumers. Higher walnut consumption was associated with a lower risk of total and CVD mortality and a greater gained life expectancy among U.S. elder adults.

Keywords: cardiovascular death; life expectancy; mortality; nuts; walnut.

Figure 1

HRs (95% CIs) of total and cause-specific mortality per 0.5 serving increase in walnut consumption stratified by AHEI. Adjusted for covariates updated over time, including: age (continuous), sex, race (Caucasian, yes/no), smoking status (never, past, current 1 to 14 cigarettes/day, current 15 to 24 cigarettes/day, current ≥25 cigarettes/day), alcohol consumption (g/day: 0, 1–4.9, 5–14.9, 15–29.9, ≥30), physical activity (metabolic equivalent hours/week, <3, 3–8.9, 9–17.9, 18–26.9, ≥27), current multivitamin use (yes/no), current aspirin use (yes/no), family history of diabetes mellitus (yes/no), myocardial infarction (yes/no) or cancer (yes/no), and menopausal status and hormone use (premenopausal, postmenopausal never users, postmenopausal past users, postmenopausal current users, among women only), body mass index, history of diabetes mellitus (yes/no), hypertension (yes/no), or hypercholesterolemia (yes/no), other nuts, fruits, vegetables, sugar sweetened beverage, meat, dairy products, whole grain, and refined grain (serving/day), and total energy intake (kcal/day).

Figure 2

Estimated life expectancy by age and sex according to the frequency of walnut consumption. Overall life expectancy is projected from the overall mortality rate of Americans from Centers of Disease Control and Prevention (CDC) Report.