space.com
Aug 18, 2026
It’s harder to poop in space. Scientists may finally know why
AI-summarised brief · reviewed before publication
A study of 52 astronauts aboard the International Space Station found that microgravity slows intestinal transit, causing gut bacteria to shift from fermenting carbohydrates to proteins. Researchers analyzed 488 plasma samples collected before, during, and after missions, detecting 40 altered metabolites, including protein‑fermentation byproducts that rose shortly after launch and returned to baseline after re‑entry. The findings suggest dietary fiber could mitigate constipation and other health risks on long missions, while also offering insights into digestive disorders on Earth.
💡 Why It Matters
- · The research links slowed gut motility in space to protein fermentation, a mechanism that could explain astronauts’ frequent constipation and inform countermeasures for extended lunar and Martian expeditions.
