Gut & MicrobiomeAstronauts' Blood Tests Expose How Microgravity Rewires Gut Bacteria Within Weeks
A University of Copenhagen study analyzing blood samples from 52 astronauts aboard the International Space Station found that microgravity rapidly alters gut bacteria behavior. Within weeks of entering space, gut microbes shift from fermenting fiber to fermenting protein — likely because food moves more slowly through the intestines without gravity. This protein fermentation is linked to kidney stress, mood changes, and reduced focus. The findings matter beyond astronaut health: they illuminate how gut motility and microbial activity interact, with implications for Earth-based gut health, aging-related digestive slowdown, and prolonged spaceflight missions to Mars. Researchers suggest dietary countermeasures may be needed for longer journeys.
