Whole grain and refined grain consumption and the risk of hypertension: a systematic review and meta-analysis of prospective studies

A high intake of whole grains has been associated with a reduced risk of hypertension, however, studies have not been entirely consistent. Findings regarding refined grains and hypertension have also been inconsistent. We conducted a systematic review and meta-analysis of prospective cohort studies on whole grain and refined grain consumption and hypertension risk. PubMed and Embase databases were searched up to 25th of July 2024. Random effects models were used to estimate summary relative risks (RRs) and 95% confidence intervals (CIs) for the association between whole grain and refined grain intake and hypertension. Restricted cubic splines were used to investigate potential nonlinear associations. Nine cohort studies were included in the meta-analysis. The summary RR (95% CI) for high vs. low whole grain intake was 0.74 (0.59-0.93, I2 = 97%, pheterogeneity2 = 63%, pheterogeneity=0.008, n = 8). The summary RR (95% CI) for high vs. low refined grain intake was 0.94 (0.88-1.01, I2 = 7.9%, pheterogeneity=0.36, n = 5) and per 90 g/d was 0.97 (0.93-1.02, I2 = 0%, pheterogeneity=0.42, n = 4). There was no indication of publication bias in either analysis, although the number of studies was low for refined grains. There was no evidence of nonlinearity for whole grains (pnonlinearity=0.31) or refined grains (pnonlinearity=0.21), and for whole grains there was a 22% reduction in risk at 200 vs. 0 g/d. These findings provide further support for a beneficial role of whole grain consumption in relation to hypertension risk and support recommendations to increase whole grain intake in the general population. No clear association was observed between refined grains and risk of hypertension.