Abstract
Background: Metabolic syndrome (MetS) is a cluster of conditions including obesity, insulin resistance, dyslipidemia, and hypertension, with gut dysbiosis implicated in its pathogenesis. Polyphenol-rich berry extracts may modulate the gut microbiome and improve metabolic health.Methods: We conducted a 12-week double-blind, placebo-controlled trial in 120 adults with MetS. Participants were randomized to receive a polyphenol-rich berry extract (500 mg/day) or placebo. Fecal samples were collected at baseline and week 12 for 16S rRNA gene sequencing. Metabolic parameters (fasting glucose, insulin, HOMA-IR, lipids, waist circumference, blood pressure) were assessed. Primary outcomes were changes in gut microbiome composition (alpha and beta diversity) and metabolic markers.Results: The berry extract significantly increased alpha diversity (Shannon index, p=0.02) and altered beta diversity (PERMANOVA, p=0.01) compared to placebo. Specifically, Akkermansia muciniphila abundance increased (log2 fold change 1.8, qRuminococcus gnavus decreased. Metabolically, the extract reduced fasting glucose (mean difference -8.2 mg/dL, p=0.003), HOMA-IR (-1.1, p=0.01), and waist circumference (-2.3 cm, p=0.02). Changes in A. muciniphila correlated with improved insulin sensitivity (r=-0.34, p=0.004).Conclusions: Polyphenol-rich berry extract modulates gut microbiota toward a healthier profile and improves key metabolic outcomes in MetS, supporting its potential as a dietary intervention.
Keywords
metabolic syndrome, gut microbiome, polyphenols, berry extract, Akkermansia muciniphila, insulin resistance, obesity, randomized controlled trial