The separate effects of whole oats and isolated beta-glucan on lipid profile: A systematic review and meta-analysis of randomized controlled trials

Background & aims: It is well known that dietary fiber positively impacts the microbiome and health as a whole. However, the health effects of β-glucan, a dietary fiber extracted from oats, have been questioned when administered alone or incorporated into other foods. The purpose of this systematic review and meta-analysis was to evaluate the impact of oats or β-glucan supplements on the lipid profile. Methods: Randomized controlled trials with parallel-arm or crossover blinded interventions at least two weeks in duration, for hyperlipidemic or non-hyperlipidemic men and women ≥18 years of age were selected. Only single (participants blinded) or double-blinded studies that compared oat or isolated β-glucan with a placebo/control group were considered for this review. The databases EMBASE, PubMed, Web of science and CINHAL were searched, from the earliest indexed year available online to the end of January 2022. Random-effects models were used to combine the estimated effects extracted from individual studies, and data were summarized as standardized mean difference (SMD) and 95% confidence interval (95%CI). Results: A total of 811 articles were screened for eligibility, and relevant data were extracted from 28 studies, totaling 1494 subjects. Oat interventions TC (−0.61, 95%CI: −0.84;-0.39, p < 0.00001, and −0.70, 95%CI: −1.07;-0.34, p = 0.0002, respectively) and LDL (−0.51, 95%CI: −0.71;-0.31, p < 0.00001, and −0.38, 95%CI: −0.60;-0.15, p = 0.001, respectively). Moreover, isolated β-glucan interventions from parallel-arm studies decreased TC (−0.73, 95%CI: −1.01;-0.45, p < 0.00001), LDL (−0.58, 95%CI: −0.85;-0.32, p < 0.0001) and triglycerides (−0.30, 95%CI: −0.49;-0.12, p = 0.001). HDL was not altered by either oat or isolated β-glucan (p > 0.05). Conclusion: Overall, this review showed that both oat and isolated β-glucan interventions improved lipid profiles. Furthermore, the ingestion of oats or isolated β-glucan supplements are effective tools to combat dyslipidemia and should be considered in cardiovascular disease prevention.