Spirulina supplementation as an adjuvant therapy in enhancement of antioxidant capacity: A systematic review and meta-analysis of controlled clinical trials

Background Spirulina, a type of blue-green algae, is used as an adjuvant treatment of metabolic and inflammatory diseases. Evidence about the effects of spirulina on antioxidant system are conflicting. Thus, this quantitative review aimed to summarise the effects of spirulina administration on antioxidant status biomarkers. Methods Systematic searches were conducted using the PubMed/Medline, Scopus, Web of Science and EMBASE, up to May 2021. Random effect analysis was applied to perform meta-analysis. Subgroup analyses and multivariate meta-regression were performed to find heterogeneity sources. Quality assessment was conducted using Cochrane Collaboration's tool. Trim and fill analysis were also carried out in case of the presence of publication bias. Results A total of nine articles that enrolled 415 subjects were included in the present meta-analysis. Obtained findings exhibited that spirulina supplementation had marginal significant effect on total antioxidant capacity (TAC) (SMD = 0.49; 95% CI: -0.001, 0.98; P = .05) and superoxide dismutase (SOD) activity (SMD = 0.72; 95% CI: -0.03, 1.46; P = .06), while did not affect glutathione peroxidase (GPx) activity (SMD=0.27; 95% CI: -0.23, 0.77; P = .29). Conclusions Spirulina consumption may exert beneficial effects on enhancement of antioxidant system. A marginal significant increasing effect on TAC and SOD activity were found by spirulina administration. However, it did not affect GPx activity.