During space travel, astronauts are exposed to a lack of gravity. This affects their physiology in different ways, including cardiovascular and musculoskeletal deconditioning, eye changes and immune dysfunction. However, less is known about the effects on the digestive system from spaceflight exposure. It’s important that we understand more about these effects because the digestive system is responsible for the absorption of nutrients and fluids from our diet that keep our bodies healthy. In turn, digestive system adaptations affect all organs in the body.

There have not been many extensive studies of the digestive system in spaceflight, though anecdotal observations suggest gastrointestinal disease and metabolic imbalances occur to crew when they travel into space. A couple of spaceflight and ground-based studies of humans and animals have found changes in gut microbiota, some from space shuttle flights from the 1980s to the 2000s. From those flights, gastrointestinal issues such as diarrhea and constipation were the third-most reported problem—after space adaptation syndrome and neurosensory changes—that the crew members experienced.

The gut microbiome may be involved in the astronauts’ digestive health because of how it maintains gut health and function, as well as overall health. Given how microbiome studies have been part of space missions since the 1960s, this is also an example of how space health research provides a platform for innovation.

The space environment provides a unique perspective in studying health because it is the only environment where we can learn about the biological adaptations to a lack of gravity. These discoveries provide us with new knowledge of health conditions on Earth. For example, gut conditions such as inflammatory bowel disease (IBD) are often considered to specifically target only the gut, though innovations from space health research have shown that IBD can affect other parts of the body, such as bone health.

As we expand the diversity of space travelers—including through NASA’s goal to send the first woman and first person of color to the moon—increasing our understanding of gut health will help them live in space. The discoveries made from our journey into space will also improve life on Earth for all.

Anand “Sunny” Narayanan, PhD, is a research professor at Florida A&M University-Florida State University. As a first-generation, immigrant Indian American, Narayanan has held a lifelong interest in encouraging diversity through educational outreach and interdisciplinary projects. His research includes studying the gastrointestinal system in various contexts, including spaceflight, medical conditions, dietary adaptations, public health and exercise.