Multiple health outcomes associated with algae and its extracts supplementation: An umbrella review of systematic reviews and meta-analyses

Algae and its extracts, widely consumed as functional foods, offer numerous health benefits; however, a comprehensive systematic summary of clinical evidence is currently lacking. The study was to assess the available evidence and provide an accurate estimate of the overall effects of algae and its extracts supplementation on various health outcomes. The comprehensive searches in PubMed, Scopus, Embase, Web of Science, and the Cochrane Library until December 22, 2023 were implemented. The random-effects model was employed to pool the overall effect sizes (ESs) and the corresponding 95% confidence intervals (CIs) using Stata software. Moreover, detecting the methodological quality and evidence level of the eligible studies were employed by A Measurement Tool to Assess Systematic Review 2 (AMSTAR2) and the Grading of Recommendations Assessment Development and Evaluation. Ultimately, 25 articles covering 133 health outcomes were included in this umbrella review. The pooled results demonstrated that the algae and its extracts could significantly decrease body weight (ES = -1.65; 95% CI: -1.97, -1.34; p < 0.001), body mass index (BMI) (ES = -0.42; 95% CI: -0.78, -0.07; p = 0.020), waist circumference (WC) (ES = -1.40; 95% CI: -1.40, -1.39; p < 0.001), triglyceride (TG) (ES = -1.38; 95% CI: -2.15, -0.62; p < 0.001), total cholesterol (TC) (ES: -1.40; 95% CI: -2.09, -0.72; p < 0.001), very low-density lipoprotein cholesterol (VLDL-C) (ES = -7.85; 95% CI: -8.55, -7.15; p < 0.001), fasting blood glucose (ES = -2.68; 95% CI: -4.57, -0.79; p = 0.005), glycated hemoglobin (HbA1c) (ES = -0.15; 95% CI: -0.24, -0.07; p < 0.001), systolic blood pressure (ES = -3.21; 95% CI: -5.25, -1.17; p = 0.002), diastolic blood pressure (ES = -3.84; 95% CI: -7.02, -0.65; p = 0.018), alanine transaminase (ES = -0.42; 95% CI: -0.70, -0.14; p = 0.003), and alkaline phosphatase (ES = -0.54; 95% CI: -0.99, -0.10; p = 0.017). Due to the limited number of studies, no benefit was displayed on markers of inflammation and oxidative stress. Considering the suboptimal quality of studies and the insufficient articles pertaining to certain outcomes, further well-designed research is imperative to substantiate the observed findings.