Spaceflight increases gut protein fermentation

A study by the University of Copenhagen in collaboration with United States — NASA analyzed blood samples from 52 astronauts who spent months aboard the International Space Station. The researchers found that within weeks of arriving in space, the astronauts' gut bacteria began fermenting protein to a greater extent than usual, a shift that persisted until they returned to Earth. The likely cause is that reduced gravity slows food movement through the intestine, leading to increased protein fermentation, which may explain the constipation commonly experienced by astronauts. The findings, published in Nature Communications, suggest that protein fermentation metabolites could have negative health effects, including kidney damage and impacts on mood and focus. The researchers propose that dietary fiber, prebiotics, or treatments to promote peristalsis could mitigate these effects for future long-duration missions to the Moon or Mars. The study also has implications for bedridden patients on Earth who experience similar digestive issues.