Efficacy of rice bran extract for alleviating depressive symptoms in adults: a randomized, double-blind, placebo-controlled trial

BACKGROUND: Preclinical research indicates the potential benefit of rice bran extract supplements (RBS) in improving depressive-like behaviors and symptoms. OBJECTIVES: We aimed to evaluate the efficacy and safety of an 8-wk administration of RBS in alleviating depressive symptoms among adults with mild-to-moderate symptom severity. METHODS: This randomized, double-blind, placebo-controlled trial included 100 adults (aged 19-75 y) with scores of 7-24 on the Korean version of the Hamilton Depression Rating Scale (K-HDRS). Participants were randomly assigned to receive 1 g/d of RBS or a placebo for 8 wk. Evaluations at baseline and after 8 wk included mood assessments using K-HDRS, the Korean version of the Beck Depression Inventory-II, the Patient Health Questionnaire-9 (K-PHQ-9), the Beck Anxiety Inventory (K-BAI), and other psychological scales. Biomarker measurements included serum brain-derived neurotrophic factor, serotonin, dopamine, and salivary cortisol. RESULTS: In the RBS and placebo groups, 47 and 50 participants, respectively, completed the intervention. At 8 wk, the RBS group exhibited greater reductions in K-HDRS scores compared with the placebo group (P < 0.001), with adjusted differences of -5.73 [95% confidence interval (CI): -7.07, -4.39; intention-to treat analysis (ITT)] and -5.95 [95% CI: -7.33, -4.57, per-protocol analysis (PP)], corresponding to percent changes of -45.1% (ITT) and -46.0% (PP), respectively. A trend toward greater reductions in the percent changes of K-BDI-II and K-BAI scores was observed in the RBS group compared with the placebo group (ITT and PP). Notably, K-PHQ-9 scores were lower in the RBS group than in the placebo group (P = 0.026, PP) after 8 wk of treatment. However, no significant intergroup differences were identified in other questionnaire scores or biomarker measurements. No adverse events were reported. CONCLUSIONS: RBS may provide a beneficial effect on depressive symptoms of mild-to-moderate severity in adults. TRIAL REGISTRATION NUMBER: This study was registered in clinicaltrials.gov with registration number NCT05180136 (https://clinicaltrials.gov/study/NCT05180136).