Context
Polyphenols are plant-based compounds with potential anti-inflammatory, antioxidant, and anti-obesogenic properties. However, their effects on health outcomes remain unclear.
Objective
To evaluate the effects of polyphenols on anthropometric and cardiometabolic markers.
Data Sources
Six electronic databases—namely, EMBASE, CINAHL, PubMed, Scopus, The Cochrane Library (reviews only), and Web of Science—were searched for relevant systematic reviews with meta-analyses (SRMAs).
Data Extraction
Three reviewers performed the data extraction via a data-extraction Microsoft Excel spreadsheet.
Data Analysis
An umbrella review and meta-analysis of existing SRMAs was conducted. Eighteen SRMAs published from 2015 to 2023, representing 445 primary studies and 838 unique effect sizes, were identified. Meta-analyses were conducted using random-effects models with general inverse variance. Polyphenol-containing foods were found to significantly improve weight (-0.36 kg; 95% confidence interval [CI]: −0.62, 0.77 kg; P < 0.01, I2 = 64.9%), body mass index (−0.25 kg/m2; 95% CI: −0.34, −0.17 kg/m2; P < 0.001, I2 = 82.4%), waist circumference (−0.74 cm; 95% CI: −1.34, −0.15 cm; P < 0.01, I2 = 99.3%), low-density-lipoprotein cholesterol (−1.75 mg/dL; 95% CI: −2.56, −0.94; P < 0.001, I2 = 98.6%), total cholesterol (−1.23 mg/dL; 95% CI: −2.00, −0.46; P = 0.002, I2 = 94.6%), systolic blood pressure (−1.77 mmHg; 95% CI: −1.77, −0.93 mmHg; P < 0.001, I2 = 72.4%), diastolic blood pressure (−1.45 mmHg; 95% CI: −2.09, −0.80 mmHg; P < 0.001, I2 = 61.0%), fat percentage (−0.70%; 95% CI: −1.03, −0.36%; P < 0.001, I2 = 52.6%), fasting blood glucose (−0.18 mg/dL; 95% CI: −0.35, −0.01 mg/dL; P = 0.04, I2 = 62.0%), and C-reactive protein (CRP; including high-sensitivity-CRP [hs-CRP]) (−0.2972 mg/dL; 95% CI: −0.52, −0.08 mg/dL; P = 0.01, I2 = 87.9%). No significant changes were found for high-density-lipoprotein cholesterol (−0.12 mg/dL; 95% CI: −1.44, 0.69; P = 0.67, I2 = 89.4%) and triglycerides (−1.29 mg/dL; 95% CI: −2.74, 0.16; P = 0.08, I2 = 85.4%). Between-study heterogeneity could be explained by polyphenol subclass differences.
Conclusion
The findings of this umbrella review support the beneficial effects of polyphenols on anthropometric and metabolic markers, but discretion is warranted to determine the clinical significance of the magnitude of the biomarker improvements.
Systematic Review Registration
International Prospective Register of Systematic Reviews no. CRD42023420206.
