Effect of curcuminoids on oxidative stress: A systematic review and meta-analysis of randomized controlled trials

• We aimed to evaluate the efficacy of curcuminoids on parameters of oxidative stress.
• 7 randomized controlled trials were finally selected for the meta-analysis.
• There was a significant increase of SOD activities especially for studies ≥6 weeks.
• They also significantly reduced lipid peroxides, increased GSH and catalase activity.

The aim of the meta-analysis was to evaluate the efficacy of purified curcuminoids supplementation on plasma activities of superoxide dismutase (SOD), catalase and glutathione (GSH) and lipid peroxides as parameters of oxidative stress. Seven randomized controlled trials were finally selected for the meta-analysis. There was a significant increase of serum SOD activities after curcuminoids supplementation (weighted mean difference [WMD]: 1.15 U/mL, 95% confidence interval [CI]: 0.49–1.82, p = 0.0007). In a subgroup analysis, no significant effects was observed in the subset of studies administering curcuminoids for <6 weeks (WMD: 0.75 U/mL, 95%CI: −0.56–2.05, p = 0.26), but a significant increase of SOD activities was found with supplementation duration ≥6 weeks (WMD: 1.46 U/mL, 95%CI: 0.60–2.32, p = 0.0009). The curcuminoids significantly reduced serum lipid peroxides (WMD: −6.35 nmol/mL, 95%CI: −11.06 to −1.64, p = 0.008), increased GSH concentrations (WMD: 5.39 µg/mL, 95%CI: 1.17–9.60, p = 0.01), and catalase activity (WMD: 51.78 U/mL, 95%CI: 15.71–87.85, p = 0.005). This meta-analysis showed a significant effect of curcuminoids in elevating serum SOD and catalase activities, GSH concentrations, and reduction of serum lipid peroxides.