Association of nut consumption with total and cause-specific mortality

Abstract

Background: Increased nut consumption has been associated with a reduced risk of major chronic diseases, including cardiovascular disease and type 2 diabetes mellitus. However, the association between nut consumption and mortality remains unclear.

Methods: We examined the association between nut consumption and subsequent total and cause-specific mortality among 76,464 women in the Nurses' Health Study (1980-2010) and 42,498 men in the Health Professionals Follow-up Study (1986-2010). Participants with a history of cancer, heart disease, or stroke were excluded. Nut consumption was assessed at baseline and updated every 2 to 4 years.

Results: During 3,038,853 person-years of follow-up, 16,200 women and 11,229 men died. Nut consumption was inversely associated with total mortality among both women and men, after adjustment for other known or suspected risk factors. The pooled multivariate hazard ratios for death among participants who ate nuts, as compared with those who did not, were 0.93 (95% confidence interval [CI], 0.90 to 0.96) for the consumption of nuts less than once per week, 0.89 (95% CI, 0.86 to 0.93) for once per week, 0.87 (95% CI, 0.83 to 0.90) for two to four times per week, 0.85 (95% CI, 0.79 to 0.91) for five or six times per week, and 0.80 (95% CI, 0.73 to 0.86) for seven or more times per week (P<0.001 for trend). Significant inverse associations were also observed between nut consumption and deaths due to cancer, heart disease, and respiratory disease.

Conclusions: In two large, independent cohorts of nurses and other health professionals, the frequency of nut consumption was inversely associated with total and cause-specific mortality, independently of other predictors of death. (Funded by the National Institutes of Health and the International Tree Nut Council Nutrition Research and Education Foundation.).

Figure 1. Hazard Ratios for Death from Any Cause and from Specific Causes, According to Frequency of Nut Consumption and Type of Nut

Multivariate hazard ratios for death among study participants who consumed nuts two or more times per week versus those who never consumed nuts were adjusted for age; race; body-mass index; level of physical activity; status with regard to smoking, whether a physical examination was performed for screening purposes, current multivitamin use, and current aspirin use; status with regard to a family history of diabetes mellitus, myocardial infarction, or cancer; status with regard to a history of diabetes mellitus, hypertension, or hypercholesterolemia; intake of total energy, alcohol, red or processed meat, fruits, and vegetables; and, for women, menopausal status and hormone use. For further details of these variables, see Figure S1 in the Supplementary Appendix. Results were pooled with the use of the random- effects model. P>0.05 for heterogeneity between women and men in all categories of nut consumption. The risk estimates for other categories of nut consumption are shown in Table S8 in the Supplementary Appendix. Horizontal lines represent 95% confidence intervals.

Figure 2. Hazard Ratios for Death from Any Cause in Subgroups

Multivariate hazard ratios for death from any cause among study participants who consumed nuts two or more times per week versus those who never consumed nuts were adjusted for age; race; body-mass index; level of physical activity; status with regard to smoking, whether a physical examination was performed for screening purposes, current multivitamin use, and current aspirin use; status with regard to a family history of diabetes mellitus, myocardial infarction, or cancer; status with regard to a history of diabetes mellitus, hypertension, or hypercholesterolemia; intake of total energy, alcohol, red or processed meat, fruits, and vegetables; and, for women, menopausal status and hormone use. For further details of these variables, see Figure S1 in the Supplementary Appendix. Results were pooled with the use of the random-effects model. P>0.05 for heterogeneity between women and men in all categories of nut consumption. The risk estimates for other categories of nut consumption are shown in Table S9 in the Supplementary Appendix. Horizontal lines represent 95% confidence intervals.