Efficacy of highly bioavailable oral curcumin in asymptomatic or mild COVID-19 patients: a double-blind, randomized, placebo-controlled trial

Abstract

Introduction Even after the peak of the COVID-19 pandemic, the number of mild cases remains high, requiring continuous control. Curcumin, owing to its anti-inflammatory properties, can suppress vital proliferation and cytokine secretion in animal models. We developed a highly absorbable curcumin, curcuRouge® (cR), which is approximately 100 times more orally bioavailable than conventional curcumin. We evaluated the effect of cR on the inhibition of disease progression in asymptomatic or mildly symptomatic COVID-19 patients. Methods This study evaluated the effect of 7-day oral intake of cR (360 mg twice daily). Patients within 5 days of COVID-19 diagnosis were randomly assigned to a placebo or cR group in a double-blind manner. Results Primary endpoint events [body temperature (BT) ≥ 37.5 °C and saturation of percutaneous oxygen (SpO2) < 96%] were fewer than expected, and the rate of these events was 2.8% in the cR group (2/71) and 6.0% in the placebo group (4/67); hazard ratio (HR) = 0.532, 95% confidence interval (CI) 0.097–2.902. Patients receiving cR tended to take fewer antipyretic medications than those receiving placebo (HR = 0.716, 95% CI 0.374–1.372). Among patients with a normal range of BT at baseline, the BT change rate was significantly (p = 0.014) lower in the cR group (− 0.34%) versus placebo (− 0.01%). Conclusion The relative suppression of event rates and antipyretic medications taken, and significant decrease of subclinical BT support the anti-inflammatory effects of cR in asymptomatic or mildly symptomatic patients with COVID-19. Trial registration: Japan Registry of Clinical Trials (CRB5200002).