In a study published in the journal Cell Reports Medicine, researchers evaluated the frequency of weekly bowel movements and the overall health of 1,400 healthy adults. The participants were separated into four groups: constipated (one to two bowel movements per week), low-normal (three to six bowel movements per week), high-normal (one to three bowel movements per day) and diarrhea. The scientists also gathered information about the participants’ age, sex, genetics and gut microbiomes.

The study revealed that age, sex and body mass index (BMI) significantly influenced bowel movement frequency. Younger individuals, females and those with a low BMI tended to have less frequent bowel movements.

Individuals in the high-normal group—deemed by researchers to be optimal—had similar gut microbiomes that efficiently converted fiber into beneficial short-chain fatty acids. Those with less frequent bowel movements had gut microbes that consumed the available dietary fiber, leading to protein fermentation and the release of harmful toxins into the bloodstream. The researchers hypothesized that these toxins could be the link between bowel health, inflammation and an increased risk of chronic diseases.

Participants with constipation had higher levels of byproducts of protein fermentation in their blood, which is known to damage the kidneys. Those with diarrhea had blood plasma patterns associated with liver damage. The study underscores the importance of dietary and lifestyle choices, such as increasing the intake of fruits and vegetables, to normalize bowel movement frequency.