People with fewer weekly bowel movements showed higher levels of bacteria associated with protein fermentation. This metabolic shift promotes the production of microbial toxins that can be harmful to various organs. These bacteria tend to replace those that produce short-chain fatty acids, beneficial compounds that help the intestines function efficiently.
In contrast, individuals with very frequent bowel movements displayed blood markers linked to inflammation, reduced microbial diversity, and greater susceptibility to digestive disturbances. Although for different reasons, both extremes appeared to reflect a gut environment under stress.
Microbial Toxins and Risks to Vital Organs
One of the study’s most consistent findings was the elevated presence of microbiome-derived compounds in the bloodstream, including p-cresol sulfate, phenylacetylglutamine, and indoxyl sulfate, particularly among people with infrequent bowel movements. These substances have previously been associated with kidney damage, systemic inflammation, and cognitive decline.
Indoxyl sulfate stood out because of its strong association with reduced kidney function. Even among individuals considered healthy, higher levels of this metabolite were linked to lower glomerular filtration rates, an early indicator of kidney performance.
Statistical analysis also suggested that part of the impact of slow intestinal transit on kidney function may be mediated by indoxyl sulfate itself. In other words, infrequent bowel movements could contribute to the buildup of toxins that place increasing stress on the kidneys over time.
Lifestyle Habits and Dietary Patterns
In addition to biological measurements, the study evaluated questionnaires covering diet, emotional well-being, lifestyle factors, and digestive health. Participants with lower bowel movement frequency generally consumed fewer fruits and vegetables, which provide fiber that helps support healthy bowel function. They also reported eating more ultra-processed snack foods.
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