N-acetylecysteine, a powerful agent in the reinforcement of anti-oxidant profile: A systematic review and dose-response meta-analysis of controlled clinical trials.

ABSTRACT

BACKGROUND AND AIM: Several studies have been conducted to evaluate the effect of N-acetylecysteine (NAC) supplementation on antioxidant status, while no dose-response meta-analysis summarized the efficacy of NAC supplementation. METHODS: The systematic search of literatures was conducted on Scopus, PubMed, Embase, Web of Science electronic databases. Controlled clinical trials investigating the effects of NAC on antioxidant biomarkers were included in the current meta-analysis. Random-effect model was used to perform meta-analysis. Heterogeneity was examined using I2 index. Subgroup analysis was carried out to find the possible sources of heterogeneity. Dose-response analysis was performed to find the non-linear relationships between effect size and independent variables. RESULTS: Overall, 26 eligible studies were included in the review. NAC supplementation significantly increased TAC (SMD = 0.77 µmol/L; 95% CI 0.38, 1.16; p < 0.001), GSH (SMD = 0.80 nmol/ml; 95% CI0.25, 1.34; p = 0.004) and CAT (SMD = -0.57 IU/L; 95% CI-1.13, -0.02; p = 0.042) levels. However, no significant improving effect was observed in terms of GR (SMD = 0.25 IU/g; 95% CI-0.14, 0.63; p = 0.210), SOD (SMD = 0.14 U/ml; 95% CI-0.20, 0.49; p = 0.414) and GPx (SMD = 0.19 IU/g; 95% CI-0.48, 0.86; p = 0.576) levels. Furthermore, dose-response analysis show that NAC supplementation in participants with mean age up to 30 years had more robust effect on increasing GSH levels. CONCLUSION: We found a significant effect of NAC supplementation on TAC, GSH, CAT in adults. Overall, NAC could be considered as a potent agent in enhancing antioxidant capacity.