The effects of rice bran supplementation for management of blood lipids: A GRADE-assessed systematic review, dose–response meta-analysis, and meta-regression of randomized controlled trials

BACKGROUND: We aimed to conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) to investigate the effects of rice bran supplementation on serum lipid profile levels. METHODS: We searched PubMed/Medline, Scopus, ISI Web of Science, and Google Scholar using related keywords. Published RCTs exploring the effects of rice bran consumption on lipid profile were searched up to June 2022. Evidence certainty was assessed on the basis of the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) approach. The data were pooled using a random-effects model and reported as weighted mean difference (WMD) and 95% confidence interval (CI) for each outcome. RESULTS: Meta-analysis of eight RCTs (with 11 effect sizes) showed no significant effect of rice bran supplementation on serum levels of triglyceride (WMD: -11.38 mg/dl; 95% CI: -27.73, 4.96; P = 0.17), total cholesterol (WMD: -0.68 mg/dl; 95% CI: -7.25, 5.88; P = 0.834), low-density lipoprotein cholesterol (WMD: -1.68 mg/dl; 95% CI: -8.46, 5.09; P = 0.627) and high-density lipoprotein cholesterol (WMD: 0.16 mg/dl; 95% CI: -1.52, 1.85; P = 0.848) compared to control group. CONCLUSION: Our meta-analysis suggests that rice bran supplementation has no significant effects on serum levels of lipid profile components. However, larger studies with longer durations and improved methodological quality are needed before firm conclusions can be reached. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13643-023-02228-y.