On September 28, researchers from the University of Copenhagen and NASA revealed that the lack of gravity in space fundamentally alters the human digestive system within weeks. By analyzing blood metabolites from 52 space station crew members, scientists discovered a distinct metabolic shift during spaceflight that explains why astronauts frequently suffer from severe constipation.
Microgravity Slows Intestinal Transit
Without Earth’s gravitational pull, dietary material moves at a significantly reduced pace through the digestive tract. Because the food lingers much longer in the intestines, gut bacteria deplete the available dietary fiber and are forced to break down proteins instead. This elevated protein fermentation begins shortly after leaving the atmosphere and persists throughout the entire duration of the mission in microgravity.
Health Risks and Future Countermeasures
The chemical byproducts generated when bacteria digest protein can enter the bloodstream and negatively impact overall health, potentially damaging kidneys and impairing focus via the gut-brain axis. As space agencies prepare for extended journeys to Mars, mitigating this digestive slowdown is essential. Scientists suggest that boosting dietary fiber intake, utilizing targeted prebiotics, or administering treatments to stimulate muscle contractions could accelerate transit times, offering a vital protective strategy for future space crews and bedridden patients on Earth facing similar gastrointestinal delays.