The Effect of Algae Supplementation on Anthropometric Indices in Adults: A GRADE-Assessed Systematic Review and Meta-Analysis of Randomized Controlled Trials.

Context: Inconsistent results have been reported regarding the effects of different types of algae, such as Spirulina and Chlorella, on anthropometric indices.

Objective: To conduct a meta-analysis to assess the efficacy of algae supplementation on anthropometric indices.

Data Sources: A comprehensive systematic search was conducted to find relevant articles published from January 1990 to January 2024.

Data Extraction: Randomized controlled trials (RCTs) comparing algae supplementation with a placebo or control group were included. The risk of bias and certainty of the evidence were evaluated using the Cochrane risk-of-bias tool and the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology, respectively. The random-effects model was used to find the Weighted mean differences (WMDs) for each outcome.

Data Analysis: Of 9079 distinct articles in the initial screening, 61 clinical trials were included in this meta-analysis. Algae supplementation resulted in lower body mass index (WMD, -0.27 kg/m2 (95% CI, -0.42 to -0.13); GRADE rating, low), body weight (WMD: -0.78 kg [-1.18 to -0.38]; GRADE rating, low), waist circumference (WMD, -0.68 cm [-1.27 to -0.10]; GRADE rating, very low), kilograms of body fat (WMD, -0.65 kg [-1.13 to -0.17]; GRADE rating, low), and body fat percentage (WMD, -0.9% [-1.62 to -0.17]; GRADE rating, very low) compared with placebo or controls. Nevertheless, the statistically significant effects of algae supplementation on hip circumference (WMD, -0.20 cm [-0.73 to 0.32]; GRADE rating, moderate), waist to hip ratio (WMD, -0.01 [-0.01 to 0.00]; GRADE rating, moderate), and lean body mass (WMD, -0.30 kg [-0.62 to 0.02]; GRADE rating, moderate) were not observed.

Conclusions: Overall, the findings of this meta-analysis indicate supplementation with algae may exert beneficial effects on anthropometric indices. However, due to between-studies heterogeneity and very low to low levels of GRADE for significant outcomes, the results should be interpreted with caution.

Systematic Review Registration: PROSPERO registration no. CRD42024522923.