Meta-analysis of prospective studies on the effects of nut consumption on hypertension and type 2 diabetes mellitus.

BACKGROUND: Inconclusive reports have been published on the consumption of nuts and the risk of hypertension and type 2 diabetes mellitus (T2DM). We performed a meta-analysis of prospective studies to assess the effects of nut consumption on hypertension and T2DM risks.

METHODS: A PUBMED and EMBASE database search was performed. Summary relative risks (SRRs) and 95% confidence intervals (CIs) were calculated using a random-effects model. Q and I2 statistics were used to examine between-study heterogeneity.

RESULTS: A total of eight articles with nine prospective cohort studies (three hypertension studies and six T2DM studies) were selected. Using random effects models, we found that compared with never/rare consumers of nuts, those consuming >2 servings per week had an 8% lower risk of hypertension (SRR = 0.92, 95% CI: 0.87-0.97, P(heterogeneity)  = 0.590, I2  = 0%), while consumption of nuts at one serving per week had similar risk (SRR = 0.97, 95% CI: 0.83-1.13). In addition, nuts consumption was not associated with risk of T2DM (SRRs = 0.98, 95% CI: 0.84-1.15; P(heterogeneity)  = 0.008, I2  = 67.7%) on the basis of the highest versus lowest analysis. This null association was also shown in the dose-response analysis.

CONCLUSION: Findings from this meta-analysis indicate that consumption of nuts (>2 servings/week) may be inversely associated with hypertension risk, but not with T2DM risk.