High-fiber diet keeps gut microbes from eating the colon’s lining, protects against infection
It sounds like the plot of a 1950s science fiction movie: normal, helpful bacteria that begin to eat their host from within, because they don’t get what they want.
But new research shows that’s exactly what happens when microbes inside the digestive system don’t get the natural fiber that they rely on for food.
Starved, they begin to munch on the natural layer of mucus that lines the gut, eroding it to the point where dangerous invading bacteria can infect the colon wall.
In a new paper in Cell, an international team of researchers show the impact of fiber deprivation on the guts of specially raised mice. The mice were born and raised with no gut microbes of their own, then received a transplant of 14 bacteria that normally grow in the human gut. Scientists know the full genetic signature of each one, making it possible to track their activity over time.
The findings have implications for understanding not only the role of fiber in a normal diet, but also the potential of using fiber to counter the effects of digestive tract disorders.
“The lesson we’re learning from studying the interaction of fiber, gut microbes and the intestinal barrier system is that if you don’t feed them, they can eat you,” says Eric Martens, Ph.D., an associate professor of microbiology at the University of Michigan Medical School who led the research along with his former postdoctoral fellow Mahesh Desai, Ph.D., now at the Luxembourg Institute of Health.
Mahesh S. Desai et al. A Dietary Fiber-Deprived Gut Microbiota Degrades the Colonic Mucus Barrier and Enhances Pathogen Susceptibility. Cell, November 2016 DOI: 10.1016/j.cell.2016.10.043
When mice were raised germ-free, then given a transplant of human gut microbes, the impact of fiber on their colons could be seen. Mice fed a high-fiber diet maintained a thick mucus layer along the lining of their colons, while those that received a fiber-free diet saw the mucus layer grow thinner as bacteria capable of digesting mucus proliferated. The thin layer allowed a pathogen bacteria access to the cells of the colon wall. Credit: University of Michigan
