Nut consumption and incidence of cardiovascular diseases and cardiovascular disease mortality: a meta-analysis of prospective cohort studies

CONTEXT: Previous meta-analyses evaluating the association between nut consumption and the risk of cardiovascular disease (CVD) had substantial methodological limitations and lacked recently published large prospective studies; hence, making an updated meta-analysis highly desirable. OBJECTIVE: To update the clinical guidelines for nutrition therapy in relation to the European Association for the Study of Diabetes (EASD), a systematic review and meta-analysis of prospective studies was conducted using the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) system to summarize the evidence of the association between total nuts, specific types of nuts, and the incidence of, and mortality from, CVD outcomes. DATA SOURCES: Relevant articles were identified by searching the PubMed and Cochrane databases. DATA EXTRACTION: Two independent researchers screened the articles to identify those that met the inclusion criteria. DATA ANALYSIS: The inverse variance method with fixed-effect or random-effects models was used to pool data across studies (expressed as risk ratio [RR] and 95% confidence interval [CI]). Heterogeneity was tested and quantified using the Cochrane Q test and I(2)-statistic, respectively. The GRADE system was used to assess the quality of the evidence. RESULTS: Nineteen studies were included in the analyses. The results revealed an inverse association between total nut consumption (comparing highest vs lowest categories) and CVD incidence (RR, 0.85; 95%CI, 0.800.91; I(2), 0%), CVD mortality (RR, 0.77; 95%CI, 0.72–0.82; I(2), 3%), coronary heart disease (CHD) incidence (RR, 0.82; 95%CI, 0.69–0.96; I(2), 74%), CHD mortality (RR, 0.76; 95%CI, 0.67–0.86; I(2), 46%), stroke mortality (RR, 0.83; 95%CI, 0.75–0.93; I(2), 0%), and atrial fibrillation (RR, 0.85; 95%CI, 0.73–0.99; I(2), 0%). No association was observed with stroke incidence and heart failure. The certainty of the evidence ranged from moderate to very low. CONCLUSIONS: This systematic review and meta-analysis revealed a beneficial role of nut consumption in reducing the incidence of, and mortality from, different CVD outcomes.