Consumption of whole grains and refined grains and associated risk of cardiovascular disease events and all-cause mortality: a systematic review and dose-response meta-analysis of prospective cohort studies

Abstract

BackgroundAlthough relationships between the intake of whole grains and refined grains and the incidence of cardiovascular disease (CVD) events and all-cause mortality have been investigated, the conclusions have been inconclusive. ObjectivesWe aimed to comprehensively summarize the evidence about the correlation between consuming whole grains and refined grains and risks of CVD events and all-cause mortality and to evaluate the meta-evidence quality. MethodsWe searched PubMed, Embase, and Web of Science until 15 March, 2022. Random-effects models were employed to calculate summary relative risks (RRs) and 95% confidence intervals (CIs). We explored potential linear or nonlinear relationships using restricted cubic splines. The NutriGrade tool was employed to rate meta-evidence quality. ResultsTwenty-four articles (68 studies; 46 for whole grains and 22 for refined grains) with 1,624,407 participants were included. Per 30-g increase in daily whole grain consumption, the RRs and 95% CIs of stroke, coronary heart disease (CHD), heart failure (HF), CVD, and all-cause mortality were 0.98 (0.96, 1.00), 0.94 (0.92, 0.97), 0.97 (0.89, 1.07), 0.92 (0.88, 0.96), and 0.94 (0.92, 0.97), respectively. Whole grain consumption was linearly associated with CHD (Pnonlinearity = 0.231) and nonlinearly associated with CVD (Pnonlinearity = 0.002) and all-cause mortality (Pnonlinearity = 0.001). Except for a positive correlation between refined grain consumption and all-cause mortality in the restricted cubic spline, no significant influence of refined grain intake on stroke, CHD, HF, and CVD was detected. The meta-evidence quality for the association of whole grain consumption with stroke, CHD, HF, CVD, and all-cause mortality was moderate, moderate, low, high, and high, respectively. For refined grains, all meta-evidence was of low quality. ConclusionsConsuming whole grains, rather than refined grains, can assist in preventing CHD, CVD, and all-cause mortality. Relationships between consumption of refined grains and health outcomes should be interpreted cautiously because of the low quality of meta-evidence.