Beneficial effects of Chlorella species supplementation in the general population: a GRADE-assessed systematic review...

This systematic review and meta-analysis aimed to evaluate the potential benefits of Chlorella supplementation in the general population, with a focus on its impact across a broad spectrum of health-related biomarkers and clinical parameters. A comprehensive literature search was conducted in PubMed, CENTRAL, Web of Science, Scopus, and EMBASE databases was conducted up to February 20, 2025. A total of 24 studies were included. Chlorella supplementation led to significant reductions in body fat percentage (Weighted Mean Difference [WMD] = -0.73%, 95% Confidence Interval [CI]: -1.18 to -0.29), body mass index (BMI) (WMD = -0.30 kg/m², 95% CI: -0.48 to -0.13), weight (WMD = -1.28 kg, 95% CI: -2.00 to -0.56), waist-to-hip ratio (WMD = -0.01%, 95% CI: -0.02 to -0.01), homeostatic model assessment for insulin resistance (WMD = -0.22 units, 95% CI: -0.35 to -0.09), insulin (WMD = -0.86 μU/mL, 95% CI: -1.45 to -0.27), high sensitivity C-reactive protein (WMD = -0.56 μg/ml, 95% CI: -1.02 to -0.11), low-density lipoprotein cholesterol (WMD = -6.20 mg/dl, 95% CI: -8.33 to -4.08), total cholesterol (WMD = -8.03 mg/dl, 95% CI: -10.60 to -5.46), triglycerides (WMD = -2.91 mg/dl, 95%CI: -5.70 to -0.12), malondialdehyde (WMD = -1.84 nmol/ml; 95% CI: -3.24 to -0.45), and leptin levels (WMD = -0.71 ng/ml; 95% CI: -1.27 to -0.16). Conversely, catalase (WMD = 22.06 U/g.Hb; 95% CI: 3.19 to 40.93) increased significantly. While the evidence for BMI was rated as low, the certainty of evidence for most other outcomes was very low according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE). Our findings underscore the potential of Chlorella supplementation to support metabolic health in general population; however, given the overall very low certainty of evidence based on the GRADE assessment, these results should be interpreted cautiously.