Nut consumption and risk of cardiovascular disease, total cancer, all-cause and cause-specific mortality: a systematic review and dose-response meta-analysis of prospective studies

Background: Although nut consumption has been associated with a reduced risk of cardiovascular disease and all-cause mortality, data on less common causes of death has not been systematically assessed. Previous reviews missed several studies and additional studies have since been published. We therefore conducted a systematic review and meta-analysis of nut consumption and risk of cardiovascular disease, total cancer, and all-cause and cause-specific mortality. Methods: PubMed and Embase were searched for prospective studies of nut consumption and risk of cardiovascular disease, total cancer, and all-cause and cause-specific mortality in adult populations published up to July 19, 2016. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated using random-effects models. The burden of mortality attributable to low nut consumption was calculated for selected regions. Results: Twenty studies (29 publications) were included in the meta-analysis. The summary RRs per 28 grams/day increase in nut intake was for coronary heart disease, 0.71 (95% CI: 0.63-0.80, I-2 = 47%, n = 11), stroke, 0.93 (95% CI: 0.83-1.05, I-2 = 14%, n = 11), cardiovascular disease, 0.79 (95% CI: 0.70-0.88, I-2 = 60%, n = 12), total cancer, 0.85 (95% CI: 0.76-0.94, I-2 = 42%, n = 8), all-cause mortality, 0.78 (95% CI: 0.72-0.84, I-2 = 66%, n = 15), and for mortality from respiratory disease, 0.48 (95% CI: 0.26-0.89, I-2 = 61%, n = 3), diabetes, 0.61 (95% CI: 0.43-0.88, I-2 = 0%, n = 4), neurodegenerative disease, 0.65 (95% CI: 0.40-1.08, I-2 = 5.9%, n = 3), infectious disease, 0.25 (95% CI: 0.07-0.85, I-2 = 54%, n = 2), and kidney disease, 0.27 (95% CI: 0.04-1.91, I-2 = 61%, n = 2). The results were similar for tree nuts and peanuts. If the associations are causal, an estimated 4.4 million premature deaths in the America, Europe, Southeast Asia, and Western Pacific would be attributable to a nut intake below 20 grams per day in 2013. Conclusions: Higher nut intake is associated with reduced risk of cardiovascular disease, total cancer and all-cause mortality, and mortality from respiratory disease, diabetes, and infections.