Abstract
This systematic review and meta-analysis was conducted to investigate the effects of Chlorella supplementation on cardiometabolic health indicators in individuals with overweight or obesity. A systematic search of PubMed, Scopus, Embase, Web of Science, and the Cochrane Central Register of Controlled Trials was conducted up to November 2024. Eighteen studies published between 2012 and 2024 were included, involving a total of 717 participants. The duration of the trials ranged from 1 to 12 weeks, with daily Chlorella doses varying from 135 to 15,000 mg/day. Chlorella supplementation significantly reduced body fat percentage (WMD = -0.72%, 95% CI: -1.11 to -0.34), body mass index (WMD = -0.35 kg/m(2), 95% CI: -0.55 to -0.14), weight (WMD = -1.41 kg; 95% CI: -2.19 to -0.64), Waist-Hip Ratio (WMD = -0.01, 95% CI: -0.02 to -0.01), Homeostatic Model Assessment for Insulin Resistance (WMD = -0.16 units, 95% CI: -0.29 to -0.04), insulin levels (WMD = -1.00 μU/mL, 95% CI: -1.34 to -0.66), low-density lipoprotein cholesterol (WMD = -5.73 mg/dL, 95% CI: -8.77 to -2.70), total cholesterol (WMD = -6.62 mg/dL, 95% CI: -10.18 to -3.05), triglycerides (WMD = -3.24 mg/dL, 95% CI: -6.25 to -0.23), alanine aminotransferase (WMD = -5.22 IU/L, 95% CI: -8.78 to -1.65), aspartate aminotransferase (WMD = -3.45 IU/L, 95% CI: -5.00 to -1.90), and leptin (WMD = -0.66 ng/mL, 95% CI: -1.24 to -0.08). Additionally, there were significant increases in catalase activity (WMD = 19.15 IU/g Hb, 95% CI: 0.44 to 37.85), and superoxide dismutase levels (WMD = 20.53 U/L, 95% CI: 15.03 to 26.02). Chlorella supplementation may benefit anthropometric and cardiometabolic outcomes in adults with overweight or obesity. However, the overall certainty of evidence was low to very low according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) framework, limiting confidence in these findings. Moreover, most included trials were conducted in Iran, which may restrict generalizability. Further high-quality, well-powered randomized trials in diverse populations are needed to confirm these effects.