NEW research has emphasised the importance of dietary fibre in protecting the gut from infection, a component recommended as an integral constituent of a healthy diet by nutritionists for a long time. This study sought to uncover the underlying mechanism behind this recommendation.
Researchers carried out a study on mice specifically bred to have no gut bacteria of their own that had received a transplant of 14 bacteria which are typically colonisers of the human gut. Knowing the genetic signature of each bacterium enabled the researchers to track their evolution and activity over time. The mice were infected with a strain of bacteria that is the equivalent of Escherichia coli in humans to induce an infection. Following infection, the impact of three different diets was considered: one with no fibre, one that was 15% fibre from minimally processed plants and grains, and one rich in prebiotic fibre.
A comparison of the different diets revealed that the most effective diet for preventing the spread of the induced infection was the 15% fibre diet. In mice on this diet, the gut’s mucus layer remained thick, protecting them from infection, and the infection did not fully spread. However, in mice on the other two diets, gut microbes started invading the colon wall, leading to the mucus layer eroding, and increasing the spread of infection. This impact was found after only a few days on the diets, highlighting the importance of a fibre-rich diet.
Further investigation discerned that a lack of dietary fibre led to the bacteria in the gut producing a greater number of mucus-degrading enzymes, which led to mucus in the gut being eroded at a far higher pace than it was reduced, exposing the gut to greater risk of infection. Co-study leader, Assoc Prof Eric Martens, Microbiology and Immunology, Center for Microbial Systems, University of Michigan, Ann Arbor, Michigan, USA, summed up the research, commenting: “While this work was in mice, the take-home message for humans amplifies everything that doctors and nutritionists have been telling us for decades: eat a lot of fibre from diverse natural sources. Your diet directly influences your microbiota, and from there it may influence the status of your gut’s mucus layer and tendency toward disease. But it is an open question of whether we can cure our cultural lack of fibre with something more purified and easy to ingest than a lot of broccoli.”