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Frequency of bowel movements That could affect a lot more than just whether or not you experience unpleasant bloating: New research suggests how often you experience it could also affect your gut microbiome and your risk of chronic disease.
For example, gut bacteria that digest dietary fiber appear to thrive in subjects who had one or two bowel movements per day, says the study published Monday in the journal Neurology. Cell Report MedicineHowever, bacteria associated with the upper gastrointestinal tract and protein fermentation were more abundant in patients with diarrhea and constipation, respectively.
The authors also found that younger people, women, and participants with a lower BMI had lower bowel movement frequency.
“Many people with chronic illnesses such as Parkinson’s disease and chronic kidney disease report struggling with constipation years before they were diagnosed,” said Dr. Shawn Gibbons, lead author of the study, who has lost family members to Parkinson’s disease.
“However, it is unclear whether these abnormalities in bowel frequency are a cause of disease or simply a consequence of disease,” Gibbons, an associate professor at the Institute for Systems Biology in Seattle, added in an email.
This conundrum prompted researchers to study the relationship between bowel movement frequency and genetics, gut microbiota, plasma chemistry, and blood metabolites (small molecules involved in bowel movements). Metabolites Gibbons says the idea is to assess whether the patterns are having a negative impact on the body before diagnosing an illness.
The authors looked at health and lifestyle data from more than 1,400 healthy adults who participated in the scientific wellness program of consumer health company Arrivale, which operated in Seattle from 2015 to 2019. About 83% of the participants were white, and they completed questionnaires and consented to the collection of blood and stool samples.
Self-reported bowel frequency was categorized into four groups: constipation (1-2 bowel movements per week), low-normal (3-6 bowel movements per week), high-normal (1-3 bowel movements per day), and diarrhea.
The authors also found that several blood metabolites and plasma chemical constituents were associated with different frequencies. By-products of protein fermentation, such as paracresol sulfate and indoxyl sulfate, which are known to cause kidney damage, were more prevalent in constipated subjects. Blood levels of indoxyl sulfate were also associated with reduced kidney function. Chemical constituents associated with liver damage were also higher in people with diarrhea, and people with diarrhea also had more inflammation.
The authors believe their findings provide “preliminary support for a causal relationship between stool frequency, gut microbial metabolism, and organ damage.” To news release.
“What excites me about this study is that while the association between constipation and chronic kidney disease has long been known, the underlying mechanisms have not been well understood until now,” Dr. Kyle Stohler, director of the Gastrointestinal Motility Laboratory at Massachusetts General Hospital and associate professor of medicine at Harvard Medical School, said in an email.
“This study points the way forward for future studies to investigate this association longitudinally to see whether people who have infrequent bowel movements produce more potentially toxic metabolites and therefore develop kidney disease,” added Staller, who was not involved in the study.
Understanding Gut Health
“This study has several important limitations that make its findings unlikely to generalize to the general population,” Staller said, including that the study doesn’t prove causation. The data comes from participants studied at a specific time point, so other factors may be at play. It’s also possible that a person’s gut microbiome influences bowel movement frequency.
Stool frequency isn’t the most ideal indicator of bowel function, either, he says.
“We know that normal bowel movement frequency ranges from three times a week to three times a day, but the best measure of how quickly things are moving through your intestines is the shape of your stool,” Staller added. “So the harder the stool is, the longer it stays in your colon and the longer the transit time.”
“The opposite is true for soft stools. Therefore, a more ideal measure of bowel function is stool consistency, rather than bowel frequency.”
Moreover, most of the study findings were based on groups with infrequent or normal bowel movements (three to six times a week), with few results from patients with constipation or diarrhea, the experts said.
“Ideally, we would see a sort of dose-response relationship where the more constipated you are, the worse your kidney function will be and the more potentially harmful metabolites you have in your blood.”
Additionally, the bacterial species in participants’ stool were detected using a type of technology that only shows the larger group or genus the bacteria belong to, rather than the specific species they belong to. It’s possible that the same group may have different effects on certain species, he added.
Participants whose bowel movements were generally normal also had important lifestyle differences, such as eating more fruits and vegetables, drinking more fluids and getting more exercise, said Dr. Lena Yadrapati, a professor of gastroenterology at the University of California, San Diego, who was not involved in the study.
The potential process behind the authors’ hypothesis isEstablished in previous studies “Gut bacteria switch between fiber fermentation and protein fermentation depending on gut transit time,” Gibbons said in an email. “During normal transit times (normal BMF), gut bacteria ferment dietary fiber into healthy organic acids that maintain gut homeostasis.
“But if stool stays in the intestine too long (constipation), the microbes start to get starved of fiber and switch to fermenting protein (and feeding on the protein-rich mucus layer),” Gibbons adds. “Protein fermentation in the gut gives rise to these toxic compounds that are found in the blood.”
All things considered, Staller said no one thinks the findings are a reason to worry about fast bowel movements: “Much of the data comes from people who we doctors consider normal, and there aren’t enough people who are truly constipated to draw any firm conclusions.”
More importantly, he added, the study reaffirms that dietary factors can also influence gut function.
Experts’ understanding of the interactions between gut bacteria and bodily functions is “growing exponentially every day,” Staller said.
“However, attempts to simplify this knowledge into culturing an ‘ideal’ gut microbiome are still a long way off,” he added. “Our knowledge in this field is still too immature to make any fundamental changes to our lives based on the findings of such studies.”
