Effects of Polyphenols on Gut Health and Inflammation in Overweight and Obese Populations: A Systematic Review and Meta-analysis of Dose, Duration, and Food Matrix

Abstract Context Obesity and overweight are global health challenges associated with chronic low-grade inflammation and gut microbiota imbalance. Polyphenols are bioactive compounds found in plant-based foods and have shown promise in improving gut health and regulating inflammatory responses. Objective This systematic review and meta-analysis evaluated the effects of polyphenol interventions on gut microbiota composition and inflammatory biomarkers in overweight and obese individuals, based on 32 randomized controlled trials. Data Sources This systematic review and meta-analysis was conducted using electronic databases including PubMed, Web of Science, Cochrane Library, and EMBASE from their inception up to August 2024. Data Analysis Our findings highlight that intervention characteristics, such as duration, dosage, and food matrix, significantly influence outcomes. Subgroup analyses revealed that shorter interventions (<6 wk) and higher daily polyphenol doses (>400 mg) more effectively reduced interleukin (IL)-6 (2.79 mg/dL; 95% CI, -3.52 to -2.06; P = .001; 4.26 mg/dL; 95% CI, -6.29 to -2.24; P = .001), increasing anti-inflammatory IL-10 (0.25 pg/mL; 95% CI, 0.11–0.40; P = .0004; 1.49 pg/mL; 95% CI, 0.62–2.36; P = .000), and promoting beneficial gut bacteria such as Bifidobacterium spp and Akkermansia muciniphila. Conclusion Whole polyphenol-rich food was more effective than purified extracts in lowering IL-6 and C-reactive protein (CRP) levels, suggesting potential synergistic effects from the food matrix. The most notable effects were observed with interventions lasting under 6 weeks, daily polyphenol intake below 400 mg, and whole polyphenol-rich foods. These findings suggest that polyphenols may help regulate gut microbiota and inflammation in overweight and obese individuals. Systematic Review Registration PROSPERO registration no. CRD42024621376.