One to Two Bowel Movements a Day Linked to Healthier Gut and Blood Markers

CATEGORY: GUT & DIGESTIVE HEALTH

How often you empty your bowels may say more about your overall health than you would think. In a study of more than 1,400 generally healthy adults, going to the bathroom about once or twice a day was linked to the healthiest mix of gut bacteria and blood markers — while patterns at either extreme, from constipation to frequent diarrhea, were associated with early signs of strain on the kidneys or liver.¹

A “Goldilocks Zone” for Bowel Habits

Researchers sorted people into four ranges: constipation (two or fewer bowel movements per week), low-normal (three to six per week), high-normal (one to three per day), and diarrhea (frequent loose movements). Those in the roughly once-or-twice-a-day range tended to have gut communities rich in fiber-fermenting bacteria — the helpful microbes that break down plant fiber and produce compounds that nourish the lining of your intestines. Move too far in either direction and that healthy balance shifted.¹

What the Blood Markers Showed

When stool moves too slowly, gut bacteria run low on fiber and switch to fermenting protein instead, producing waste compounds the body then has to clear. In people with constipation, the researchers found higher blood levels of two such compounds — indoxyl sulfate and p-cresol sulfate — that the kidneys filter out, and these were associated with reduced kidney function. At the other end, diarrhea was linked to blood-chemistry patterns that can reflect strain on the liver. In short, both extremes coincided with markers hinting at organs working harder than they should.¹

How the Study Worked

This was an observational study, meaning it looked for patterns rather than testing a treatment — so it can show associations but cannot prove that bowel habits caused the differences. The team drew on 1,425 generally healthy adults enrolled in a wellness program between 2015 and 2019, combining their self-reported bathroom habits with genetic sequencing of their gut bacteria, blood metabolites (small molecules made during digestion), and standard blood-chemistry tests. Comparing these data across the four frequency groups is how the links to kidney and liver markers emerged.¹

What Tended to Come With a Healthy Range

People who reported eating a fiber-rich diet, staying well hydrated, and exercising regularly were more likely to fall in the once-or-twice-daily range. Bowel frequency also varied with who people were: younger adults, women, and those with a lower body weight tended toward less frequent movements. Everyday factors such as travel, stress, illness, and medications can shift your pattern too, so a change on its own is a reason to pay attention, not a diagnosis.¹

Key Takeaways

• In generally healthy adults, roughly one to two bowel movements a day was linked to the healthiest gut bacteria and blood markers.
• Because this was an observational study, it shows associations only — it cannot prove that bowel frequency causes changes in organ health.
• Constipation coincided with higher blood levels of bacterial waste compounds tied to reduced kidney function; frequent diarrhea coincided with markers of liver strain.
• Persistent constipation or diarrhea — or any blood in the stool — is worth raising with your doctor, who can look at the full picture rather than any single number.

References

1. Johnson-Martínez JP, Diener C, Levine AE, et al. Aberrant bowel movement frequencies coincide with increased microbe-derived blood metabolites associated with reduced organ function. Cell Reports Medicine. 2024;5(7):101646. link