Evaluation of the prebiotic potential of polyphenol-rich plant extracts in a mouse model of colitis
A five-week controlled animal study investigated whether polyphenol-rich plant extracts could reduce gut inflammation and support gut health during colitis in adult C57BL/6 mice. Mice were supplemented for four weeks with extracts from pomegranate peel, lemon balm leaves, cinnamon bark, or grape pomace, then exposed to dextran sulfate sodium (DSS) — a chemical commonly used to induce colitis by damaging the gut lining and triggering inflammation. Groups included healthy controls, DSS-only controls, and DSS plus each plant extract.
Researchers evaluated disease severity, including weight loss and clinical disease activity, alongside colon damage and swelling. They also measured gut microbiome composition using DNA sequencing, microbial metabolites using fecal metabolomics, gut barrier–related gene expression, and bacterial movement toward the gut lining using imaging techniques.
The study found that all four plant extracts reduced intestinal damage caused by DSS, though their effects differed. Grape pomace showed the strongest overall benefit, significantly delaying the onset of colitis symptoms and lowering disease severity compared with DSS alone (p < 0.05). Cinnamon extract helped reduce inflammation-related weight loss, while both cinnamon and grape pomace reduced colon swelling and visible tissue damage, with more consistent responses between animals. Several extracts also shifted the gut microbiome, including changes in mucus-associated bacteria such as Akkermansia muciniphila. DSS exposure increased inflammatory metabolites like ethanol and reduced beneficial short-chain fatty acids, while some extracts partially reversed these changes. Notably, grape pomace most strongly supported gut barrier function, increasing expression of genes involved in mucus production and tight junctions — the structures that keep intestinal cells sealed together — and reducing bacterial penetration into the gut lining.
These findings support the conclusion that polyphenol-rich plant extracts can act in a “prebiotic-like” manner during intestinal inflammation, not only by influencing gut microbes but also by helping preserve the gut barrier itself. Grape pomace emerged as the most promising extract in this head-to-head comparison. The study has limitations, including the use of an acute, chemically induced colitis model, short duration, and delivery of extracts by oral gavage rather than through food, which may limit real-world relevance.
Future research should explore longer-term and chronic inflammation models, clarify cause-and-effect relationships between microbes and barrier changes, and test these extracts in human clinical trials. Overall, this study reinforces the idea that plant polyphenols can meaningfully support gut health by protecting the gut lining and shaping the microbial environment during inflammation.