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.

In 30 seconds

This systematic review and meta-analysis assessed polyphenol interventions and gut microbiota and inflammatory biomarkers in people with overweight or obesity, drawing on 32 randomized controlled trials. Effects varied by intervention duration, dose, and food matrix. Subgroup analyses reported lower IL-6 with interventions under 6 weeks and with daily doses above 400 mg, alongside higher IL-10 and increases in beneficial bacteria including Bifidobacterium spp and Akkermansia muciniphila. Whole polyphenol-rich foods were more effective than purified extracts for lowering IL-6 and C-reactive protein, although the abstract’s concluding description of the most effective dose differs from its subgroup results.

Key findings

• Interventions under 6 weeks were associated with an IL-6 reduction of 2.79 mg/dL (95% CI, -3.52 to -2.06; P = .001).
• Daily doses above 400 mg were associated with an IL-6 reduction of 4.26 mg/dL (95% CI, -6.29 to -2.24; P = .001).
• Subgroup analyses reported increased IL-10 and promotion of Bifidobacterium spp and Akkermansia muciniphila.
• Whole polyphenol-rich foods lowered IL-6 and CRP more effectively than purified extracts, according to the review.

Why it matters

The findings suggest that polyphenol effects on inflammation and gut microbiota may depend not only on the compound but also on dose, duration, and whether it is consumed in a whole-food matrix. These distinctions may help frame future dietary intervention research, while the reported biomarker and microbiota outcomes do not by themselves establish clinical benefit.

What to keep in mind

The abstract reports subgroup findings across trials but provides no overall pooled effect estimates or details on between-study heterogeneity, limiting assessment of the consistency and clinical magnitude of effects.