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.

Paolo Boffetta,Serena Tonstad,Nana Keum,Lars J Vatten,Lars T Fadnes,Teresa Norat,Edward Giovannucci,Dagfinn Aune,Elio Riboli,Darren C Greenwood

doi:10.1186/s12916-016-0730-3

Abstract

BackgroundAlthough 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.MethodsPubMed 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.ResultsTwenty 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, I2 = 47%, n = 11), stroke, 0.93 (95% CI: 0.83–1.05, I2 = 14%, n = 11), cardiovascular disease, 0.79 (95% CI: 0.70–0.88, I2 = 60%, n = 12), total cancer, 0.85 (95% CI: 0.76–0.94, I2 = 42%, n = 8), all-cause mortality, 0.78 (95% CI: 0.72–0.84, I2 = 66%, n = 15), and for mortality from respiratory disease, 0.48 (95% CI: 0.26–0.89, I2 = 61%, n = 3), diabetes, 0.61 (95% CI: 0.43–0.88, I2 = 0%, n = 4), neurodegenerative disease, 0.65 (95% CI: 0.40–1.08, I2 = 5.9%, n = 3), infectious disease, 0.25 (95% CI: 0.07–0.85, I2 = 54%, n = 2), and kidney disease, 0.27 (95% CI: 0.04–1.91, I2 = 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.ConclusionsHigher nut intake is associated with reduced risk of cardiovascular disease, total cancer and all-cause mortality, and mortality from respiratory disease, diabetes, and infections.Electronic supplementary materialThe online version of this article (doi:10.1186/s12916-016-0730-3) contains supplementary material, which is available to authorized users.

Highlights

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
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
Data extraction The following data from the studies were extracted into tables: name of first author, publication year, country or Statistical methods Summary relative risk (RR) and 95% Confidence interval (CI) of cardiovascular disease, total cancer, and all-cause and cause-specific mortality for the highest versus the lowest level and per one serving per day increase in nut intake were calculated using the random effects model [48], which takes into account both within and between study variation

Summary

Introduction

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. We conducted a systematic review and meta-analysis of nut consumption and risk of cardiovascular disease, total cancer, and all-cause and cause-specific mortality. Epidemiological and intervention studies have shown that a high intake of nuts is associated with a reduced risk of coronary heart disease and possibly other health outcomes such as diabetes, overweight and obesity, gallstones, and colorectal cancer [2,3,4]. Botanically defined as dry fruit containing one seed (rarely two) within the ovary wall that becomes hard at maturity, include walnuts, almonds, hazelnuts, cashews, pistachios, and pecans [5]. Epidemiological data on nuts and cancer risk are less extensive than for cardiovascular disease

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