Blood tests of 52 astronauts explain constipation in space

Researchers at the University of Copenhagen, working with NASA, analyzed blood samples from 52 ISS astronauts and found that gut bacteria ferment protein more than usual within weeks of arriving in microgravity. The finding may explain astronauts' constipation and inform countermeasures for future Mars missions.

• The study analyzed blood samples from 52 astronauts across many missions and years
• Protein fermentation rises within weeks of arriving on the ISS
• Protein fermentation products are linked to kidney damage and mood effects
• Possible fixes include more dietary fiber, prebiotics and faster gut transit