Dietary fiber prevents gut bacteria from breaking down the protective mucus layer of the colon, according to research published in the Proceedings of the National Academy of Sciences and Nature Metabolism.
The inner lining of the colon features a mucus layer that acts as a barrier, preventing bacteria from directly contacting the intestinal wall. When dietary fiber is scarce, researchers observed that certain bacteria degrade proteins within this mucus layer to survive. This process can lead to the production of potentially harmful metabolites.
“This study shows that fiber is not just for regularity; it plays a critical role in maintaining the gut’s protective barrier,” researchers noted in their findings. When fiber is supplied, the microbial activity that degrades the mucus layer is suppressed, which subsequently reduces the production of harmful compounds.
Researchers also identified a specific role for plant-based proteins that remain undigested until they reach the gut. The team coined the term “Prif” (protein that acts like fiber) for these substances. These proteins serve as a nutrient source for beneficial gut bacteria, promoting the production of health-promoting metabolites rather than harmful ones.
The study also challenged the conventional understanding of how metabolites are generated. Experiments using mice and human cells revealed that some metabolites are produced by the body’s own cells, even in the absence of gut bacteria. This was evidenced by the presence of specific metabolites in the blood of mice treated with antibiotics to deplete their gut microbiome.
The findings suggest that future nutritional labeling may need to account for both fiber and specific undigested plant proteins to better reflect their impact on digestive health. However, researchers emphasize that these results are primarily based on animal models and laboratory cell analysis. Further clinical research is required to determine how these metabolic changes translate to human disease prevention and long-term gut health.
The degradation process produces metabolites, such as certain phenol sulfates, which have been associated with negative health outcomes, including kidney disease and poor prognosis in cancer patients. Conversely, beneficial metabolites like hippuric acid are linked to healthy body weight and healthy gut bacteria.
Yes, the study found that some metabolites are created directly by host cells. Researchers observed these substances in the blood of mice and human samples even after gut bacteria populations were significantly reduced by antibiotic treatment.
While fiber is essential for suppressing the breakdown of the protective mucus layer, the researchers suggest that a complex interplay of nutrients is involved. The inclusion of "Chief" proteins—those that reach the gut undigested—works alongside fiber to shift the balance of microbial activity toward the production of beneficial compounds.
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