Microgravity may cause constipation in astronauts, study finds

Researchers from the University of Copenhagen, in collaboration with NASA, have identified a potential cause for the chronic constipation experienced by astronauts in microgravity. A study published in Nature Communications analyzed blood samples from 52 crew members who served on the International Space Station (ISS) between 2006 and 2018.

By tracking blood metabolites, scientists observed a significant increase in molecules associated with protein fermentation within the first 50 days of orbit. This suggests that the lack of gravity likely slows intestinal transit time, causing food to remain in the gut longer. This sluggish digestion can lead to increased protein decomposition by bacteria, which may result in health complications such as kidney damage, mood changes, and difficulty concentrating.

Metabolic indicators typically returned to baseline levels approximately ten days after the astronauts returned to Earth, reinforcing the link between spaceflight conditions and digestive changes.