Rice Bran Consumption Improves Lipid Profiles: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background: Dyslipidemia, a leading risk factor for cardiovascular diseases (CVDs), significantly contributes to global morbidity and mortality. Rice bran, rich in bioactive compounds such as gamma-oryzanol and tocotrienols, has demonstrated promising lipid-modulating effects. Objective: This meta-analysis aimed to evaluate the effects of rice bran on lipid profiles, including triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C), and identify factors influencing its efficacy across different populations and intervention conditions. Methods: A systematic search of PubMed, Web of Science, and Scopus was conducted to identify randomized controlled trials (RCTs) published up to November 2024. Effect sizes were calculated as mean differences with 95% confidence intervals (CIs). Subgroup analyses were performed based on intervention form, dosage, duration, region, and participant characteristics. Heterogeneity was estimated by the I-2 statistic, and sensitivity analyses were conducted to assess the robustness of the findings. Results: Eleven RCTs involving 572 participants met the inclusion criteria. Pooled results showed that rice bran consumption significantly reduced TG (-15.13 mg/dL; 95% CI: -29.56, -0.71), TC (-11.80 mg/dL; 95% CI: -19.35, -4.25), and LDL-C (-15.11 mg/dL; 95% CI: -24.56, -5.66) with moderate heterogeneity (I-2 = 38.1-63.0%). No significant changes were observed for HDL-C. Subgroup analyses showed that rice bran oil had greater effects on TC and LDL-C than whole rice bran. High-dose interventions (>= 30 g/mL) and longer durations (>4 weeks) yielded stronger effects. Asian populations demonstrated greater reductions compared to Western populations. Conclusion: Rice bran, especially in the form of rice bran oil, significantly improves lipid profiles, supporting its role as a functional food for CVD prevention. Future research should focus on long-term studies with diverse populations to confirm its efficacy and explore underlying mechanisms.