Abstract/Summary

BACKGROUND: The decline of cognitive function could in part be caused by an increase in inflammation. Polyphenols have been widely investigated due to their anti-inflammatory property which may promote therapeutic effects on the brain and cognitive function. OBJECTIVE: To evaluate the impact of polyphenols interventions on inflammation related to cognitive function in humans. METHODS: Three electronic databases: PubMed/Medline, Web of Science and PsycINFO were systematically searched until 30th May 2024 to find the study that have investigated the effect of polyphenols on both inflammatory response and cognitive function in human randomized controlled trials. The outcomes were pooled and calculated using inverse variance as mean difference (MD) with 95% confidence intervals (95% CI) for the inflammatory markers and standardized mean difference (SMD) with 95% CI for cognitive domains. RESULTS: Ten studies (451 participants, aged 20–81 years) assessed inflammatory markers and cognitive standardized tests responding to polyphenols interventions were included in this review and meta-analysis. Supplementation with polyphenols demonstrated a significant improvement of verbal memory (SMD: 0.33, 95% CI: 0.12 to 0.54, P = 0.002), executive function (SMD: 0.38, 95% CI: 0.03 to 0.72, P = 0.03) and attenuation in blood interleukin-6 (MD: –1.23 pg/ml, 95% CI: –2.34, to –0.12, P = 0.03). No significant differences were observed in working memory (SMD: 0.13, 95% CI: –0.18 to 0.44, P = 0.42), attention (SMD: –0.19, 95% CI: –0.84 to 0.46, P = 0.57), and psychomotor skill (SMD: 0.09, 95% CI: –0.32 to 0.50, P = 0.66) as well as in c-reactive protein (MD: –0.10 mg/l, 95% CI: –0.28 to 0.09, P = 0.30), and tumor necrosis factor-α (MD: 0.11 pg/ml, 95% CI: –1.25 to 1.47, P = 0.87). CONCLUSION: Polyphenols supplementation decreases blood IL-6 as well as enhances verbal memory and executive function. Regular polyphenols consumption might prevent inflammation related to cognitive decline.