Fiber-starved gut bacteria eat your gut lining
Get the Health newsletter
Daily health & science — research, biotech, public health, the studies worth knowing. Free.
- Joshua Rabinowitz and Jenna AbuSalim at Ludwig Princeton led two studies – one in PNAS, one in Nature Metabolism – using isotope-labeled proteins in mice to trace how plant foods influence gut microbial metabolism.
- When dietary fiber runs low, gut bacteria begin consuming proteins from the host's mucus lining, producing harmful phenols like p-cresol sulfate and phenol sulfate, the PNAS study found.
- Proteins imitating fiber ('Prif') — indigestible plant proteins the researchers newly identified — give microbes more material to produce beneficial phenols like phenylpropionate and hippuric acid.
- Mammalian metabolism — not just gut microbes — produces many indole and phenol metabolites, including indole-3-lactate and indole-3-acetate, the Nature Metabolism study found. These persisted in mice and cancer patients even after antibiotics wiped out the microbiome.
- Exclusively microbial metabolites like indole-3-propionate and p-cresol sulfate declined after antibiotic treatment, contrasting with the host-produced compounds that remained stable.
- Rabinowitz suggested 'food packaging may eventually list Prif right below fiber,' positioning the new nutrient class as a potential target for dietary or probiotic interventions.
Why it matters: The discovery that mammalian metabolism — not just gut microbes — produces many indole and phenol metabolites directly challenges the assumption that boosting them requires microbial intervention, as the compounds persisted even after antibiotics. The Prif protein class gives nutritionists a previously underappreciated lever for directing the microbiome's metabolic output, with stated implications for cancer and kidney disease.
Ask SkimNews
