Effect of Oat Consumption on Blood Pressure: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Abstract

Current clinical trials have had controversial results regarding the effects of oat consumption on blood pressure (BP) in adults. The meta-analysis was conducted to systematically evaluate the effects of oat consumption on BP in adults. Electronic databases including PubMed, Web of Science, Scopus, Cochrane Library, and Embase were searched until December 13, 2021 for eligible randomized controlled trials (RCTs). RCTs published in English and that explored the effects of oat consumption on BP in adults under matched total energy intake were included. Meta-analysis using a random-effects model was performed. The pooled effect size was expressed as mean difference and 95% CI. I2 statistics were used to quantify heterogeneity. The risk of bias was assessed using the Cochrane Risk-of-Bias Tool, version2. Twenty-one RCTs involving 1,569 participants were included. The pooled results indicated that consuming oats reduced systolic blood pressure (SBP) significantly (mean difference= -2.82 mm Hg; 95% CI -4.72 to -0.93 mm Hg; P= .004). Subgroup analyses indicated that oat consumption reduced SBP significantly in hypertensive participants, or when compared with control group participants who consumed refined grains. No significant reduction in diastolic blood pressure (DBP) was observed after oat consumption (mean difference= -1.16 mm Hg; 95% CI -2.37 to 0.04 mm Hg; P= .060). However, the sensitivity analysis of DBP, removal of individual studies, or "leave one out meta-analysis," showed a significant reduction in DBP, suggesting that the pooled result in the main analysis was not robust. Subgroup analyses showed that oat consumption did significantly reduce DBP in participants with baseline BP in the prehypertensive range. Both SBP and DBP were significantly reduced when the dosage of oat consumption was ≥5 g/day β-glucan, or the oat consumption duration was ≥8 weeks. Oat consumption is effective in reducing SBP levels, particularly in individuals whose baseline BP is in the hypertensive range or when compared with control group participants consuming refined grains at matched total energy intake.