If you don’t feed your gut bacteria, they’ll eat you!
Two studies conducted by researchers at Princeton University’s Ludwig Institute for Cancer Research revealed that gut bacteria resort to consuming the protective mucous layer lining the intestines when they do not find sufficient dietary fiber to feed on. In other words, if you do not provide those gut bacteria with the appropriate food (dietary fiber), they will consume your own body cells!
The studies were led by researcher Gina Abuslim and Institute Director Joshua Rabinowitz, who clarified that plant-based diets support health by encouraging bacterial diversity in the gut. As bacteria digest amino acids such as tyrosine and phenylalanine, they release compounds known as phenol metabolites, whose effects on human health vary significantly.
Abuslim explained that phenylpropionate and hippuric acid, which are derived from phenylalanine, are associated with gut health and a healthy body weight. In contrast, p-cresol sulfate and phenol sulfate, which are derived from tyrosine, are linked to worse outcomes in cancer patients, as well as systemic toxicity in kidney disease patients.
• “Harmful” metabolites are produced when bacteria consume proteins from the host itself, including proteins from the intestinal mucous layer.
• “Beneficial” metabolites largely originate from indigestible plant proteins, which the researchers termed “fiber-mimicking proteins.”
Rabinowitz noted growing interest in the medical community in controlling the human microbiome or harnessing its metabolic products for therapeutic purposes. He emphasized that understanding which dietary components control which microbial products is essential for designing effective therapeutic interventions.
The second study focused on the origin of indole metabolites derived from tryptophan. Using isotopic tracing in mice, rats, and human cells, it showed that mammalian metabolism alone can produce significant amounts of these compounds independently of bacteria. This finding prompted researchers to reconsider previous assumptions that attributed their production exclusively to gut bacteria.
Rabinowitz stated that a clearer picture of how different foods interact with the microbiome to modify bacterial metabolite production will help dietitians and physicians generally provide more accurate guidance for disease prevention and treatment in the future.
