Association of nut consumption with total and cause-specific mortality

Abstract

Background: Nuts are known to have numerous health benefits but most such data have come from small studies only. In addition, the effect of nut consumption on the hard end-point of all-cause or disease-specific mortality has also not been studied adequately. Material and methods: Data from two large prospective studies – the Nurses' Health Study (NHS, 76,464 women) and the Health Professionals Follow-up Study (HPFS, 42,498 men) were analyzed to determine the association between nut consumption and subsequent total and cause-specific mortality. Average duration of follow-up in NHS was 30 years and in HPFS 24 years. Nut consumption (1 serving = 1 oz) was assessed at baseline and updated every 2–4 years. Participants with a history of cancer, heart disease, or stroke were excluded. Extensive statistical analyses and sub-group analyses were performed to eliminate the effects of various known and unknown confounding factors. Results: A total of 27,429 deaths (16,200 women and 11,229 men) occurred over 3,038,853 person-years of follow-up. There was a significant, dose-dependent inverse relationship between nut consumption and total mortality in both the studies. The pooled multivariate hazard ratios for death among participants who ate nuts were 0.93, 0.89, 0.87, 0.85 and 0.80 for those who consumed nuts less than once per week, once per week, two to four times per week, five or six times per week, and seven or more times per week, respectively (p < 0.001 for trend). This relationship persisted across all subgroups based on age, physical activity, body-mass index, smoking status, aspirin use, consumption of fruits/vegetables, etc. A similar beneficial effect of nut consumption was seen on cause-specific mortality also, with significant inverse associations observed for deaths due to cancer, heart disease, and respiratory disease. Finally, comparison between peanuts and tree-nuts revealed similar associations with total and cause-specific mortality for both the types of nuts. Conclusions: The two large, independent cohort studies involving nurses and other health professionals demonstrated that nut consumption was inversely associated, in a dose-dependent manner, with total and cause-specific mortality. This relationship was independent of other predictors of death.