Spaceflight slows digestion by altering gut microbes, study finds

A study of 488 plasma samples from 52 astronauts on the ISS shows microgravity slows food transit through the gut, prompting gut bacteria to ferment proteins more than usual and producing metabolites that enter the bloodstream. The effect starts within weeks in space and largely reverses after returning to Earth. Findings suggest dietary fiber or slowly fermented carbohydrates could counteract the change for long-duration missions and also offer insights into Earth-based digestive health; published in Nature Communications.