A study published in Cell Reports Medicine reveals that bowel movement frequency significantly influences physiology and long-term health, with the best outcomes linked with passing stools once or twice a day.

Previous research has suggested associations between constipation and diarrhea with higher risks of infections and neurodegenerative conditions, respectively.

But since these findings were observed in sick patients, it remained unclear whether irregular bathroom visits were the cause or result of their conditions.

A graphic depicting the studied variables
Participants provided samples of blood plasma and stool, in addition to filling out extensive diet, health, and lifestyle questionnaires. (Johnson-Martínez et al., Cell Reports, 2024)

“I do hope that this work will kind of open clinicians’ minds a bit to the potential risks of not managing bowel movement frequencies,” senior author Sean Gibbons at the Institute for Systems Biology told AFP, explaining that doctors often view irregular movements as merely a “nuisance.”

Gibbons and his team collected clinical, lifestyle, and biological data – including blood chemistry, gut microbiome, genetics and more – from over 1,400 healthy adult volunteers with no signs of active disease.

Participants’ self-reported bowel movement frequencies were categorized into four groups: constipation (one or two bowel movements per week), low-normal (three to six per week), high-normal (one to three per day), and diarrhea.

When stools linger too long in the gut, microbes exhaust the available fiber – which they ferment into beneficial short-chain fatty acids – and instead ferment proteins, producing toxins like p-cresol sulfate and indoxyl sulfate.

“What we found is that even in healthy people who are constipated, there is a rise in these toxins in the bloodstream,” said Gibbons, noting that these toxins are particularly burdensome to the kidneys.

Graphic showing the study findings
Toxins like p-cresol sulfate (PCS) and indoxyl sulfate (3-IS) in the bloodstream are particularly burdensome to the kidneys. (Johnson-Martínez et al., Cell Reports, 2024)

Fruits and vegetables key

In cases of diarrhea, the team found clinical chemistries indicative of inflammation and liver damage.

Gibbons explained that during diarrhea, the body excretes excessive bile acid, which the liver would otherwise recycle to dissolve and absorb dietary fats.

Anatomical diagram of upper body with liver highlighted
The liver usually recycles bile acid to dissolve and absorb dietary fats. (Eraxion/Canva)

Fiber-fermenting gut bacteria known as “strict anaerobes,” associated with good health thrived in the “Goldilocks zone” of one or two poops a day.

However, Gibbons emphasized that more research is needed to define this optimal range more precisely.

Demographically, younger people, women, and those with a lower body mass index tended to have less frequent bowel movements.

Hormonal and neurological differences between men and women may explain the gap, Gibbons said, along with the fact that men generally consume more food.

Food on a table with hands grabbing it
A more plant-dominant diet can have health benefits. (Prostock-studio/Canva)

Finally, by pairing biological data with lifestyle questionnaires, the team painted a clear picture of those who typically fall into the Goldilocks Zone.

“It was eating more fruit and vegetables, that was the biggest signal we saw,” said Gibbons, along with drinking plenty of water, regular physical activity, and eating a more plant-dominant diet.

The next step in the research could involve designing a clinical trial to manage the bowel movements of a large group of people, followed over an extended period to assess its potential in disease prevention.

© Agence France-Presse