Consumption of whole grains in relation to mortality from all causes, cardiovascular disease, and diabetes: Dose–response meta-analysis of prospective cohort studies

BACKGROUND: To investigate the correlation between consumption of whole grains and the risk of all-cause, cardiovascular disease (CVD), and diabetes-specific mortality according to a dose–response meta-analysis of prospective cohort studies. METHODS: Observational cohort studies, which reported associations between whole grains and the risk of death outcomes, were identified by searching articles in the MEDLINE, EMBASE, and the reference lists of relevant articles. The search was up to November 30, 2015. Data extraction was performed by 2 independent investigators, and a consensus was reached with involvement of a third. RESULTS: Ten prospective cohort studies (9 publications) were eligible in this meta-analysis. During follow-up periods ranging from 5.5 to 26 years, there were 92,647 deaths among 782,751 participants. Overall, a diet containing greater amounts of whole grains may be associated with a lower risk of all-cause, CVD-, and coronary heart disease (CHD)-specific mortality. The summary relative risks (RRs) were 0.93 (95% confidence intervals [CIs]: 0.91–0.95; P(heterogeneity) < 0.001) for all-cause mortality, 0.95 (95% CIs: 0.92–0.98; P(heterogeneity) < 0.001) for CVD-specific mortality, and 0.92 (95% CIs: 0.88–0.97; P(heterogeneity) < 0.001) for CHD-specific mortality for an increment of 1 serving (30 g) a day of whole grain intake. The combined estimates were robust across subgroup and sensitivity analyses. Higher consumption of whole grains was not appreciably associated with risk of mortality from stroke and diabetes. CONCLUSION: Evidence from observational cohort studies indicates inverse associations of intake of whole grains with risk of mortality from all-cause, CVD, and CHD. However, no associations with risk of deaths from stroke and diabetes were observed.