Polyphenols Nonmonotonically Modulate the Inulin-Driven Gut Microbial Network In Vivo

Area of Science:

• Microbiology
• Nutrition Science
• Metabolomics

Background:

• The interplay between dietary fiber and polyphenols in influencing gut microbiota remains incompletely understood.
• Polyphenols are plant-derived compounds with diverse biological activities, including potential modulation of the gut microbiome.
• Inulin, a prebiotic fiber, significantly impacts gut microbiota composition and function.

Purpose of the Study:

• To investigate the impact of polyphenol structure (tannic acid vs. ferulic acid) and dosage on gut microbiota and metabolic profiles in the context of a high-inulin diet.
• To elucidate the dose-response relationship of different polyphenols on microbial network restructuring and short-chain fatty acid (SCFA) production.
• To determine whether polyphenols act as primary drivers or subtle modulators of the gut microbiome under high-fiber conditions.

Main Methods:

• Administration of a high-dose inulin diet supplemented with varying concentrations of tannic acid or ferulic acid to a model system.
• Analysis of gut microbiota composition and network structure using advanced sequencing techniques.
• Quantification of short-chain fatty acid (SCFA) production and assessment of polyphenol tolerance and safety.

Main Results:

• All polyphenol treatments were well-tolerated, showing no adverse health effects.
• Polyphenols induced significant restructuring of the microbial network without causing large-scale shifts in overall composition.
• Distinct hub microbial species were identified for each polyphenol: Oscillospira for tannic acid and Allobaculum for ferulic acid.
• Nonmonotonic dose-response relationships were observed for SCFA production, linked to the balance of polyphenol trophic and antimicrobial effects.

Conclusions:

• In high-fiber environments, polyphenols function as subtle modulators of the gut microbiome, rather than primary drivers.
• Polyphenol structure and dosage are critical determinants of their influence on microbiome function and metabolic output.
• The observed microbial network restructuring and altered SCFA production highlight the nuanced effects of polyphenols on gut health.