Spaceflight Alters Gut Microbiome, Leading to Astronaut Constipation

Recent blood‑test analyses reveal that astronauts’ gut microbiota undergoes rapid changes within weeks of launch. The altered microbial community breaks down more protein as food transit slows, contributing to the constipation commonly reported during missions. These findings suggest that the gut’s functional shift could have broader health implications for crew members, potentially affecting nutrient absorption and immune responses. Understanding this process is critical for designing countermeasures and ensuring crew well‑being on extended missions, such as planned trips to Mars.