Muscle loss, lack of balance, backaches: human bodies act in strange ways in space. But scientists are only now starting to understand the changes that happen in the microbiome, the community of bacteria that live in our guts and elsewhere on our bodies and that have a huge effect on functions such as digestion and immunity. In space, the gut microbiome can get a bit out of whack, according to a recent article published in the International Reviews of Immunology. As commercial space travel and longer stints away from Earth seem more inevitable, researchers are trying to figure out how these changes in the gut microbiome might make humans sick in space.
Microgravity, cosmic radiation, and human stress can cause some gut bacteria to become stronger and others to become weaker, resulting in conditions similar to traveler’s diarrhea or worse. Microgravity can also prevent bacteria from communicating with one another and with the human cells around them, which could cause some kinds of bacteria to grow out of control. The microbiome provides a first line of defense against infections, but if defender bacteria don’t survive in space, that could make humans more susceptible to diseases like E. Coli. Some studies have shown that the immune cells themselves undergo a change that makes them less effective in staving off disease. With so many people living in a confined space and their immune systems compromised, it’s easy to imagine that these sorts of diseases could run rampant.
Now that researchers are beginning to understand what can go wrong in the microbiome and how much these changes can affect space travelers, they can start to find solutions. Some have suggested that astronauts eat more fermented foods made with lactic acid bacteria, such as miso or tempeh, which might be a challenge to produce if people are traveling in space for long periods of time. Other researchers are working on probiotic supplements that will help keep the gut microbiome in balance so that the travelers can stay healthy. Because each person’s microbiome is unique, it might take more time to figure out just which supplements each individual commuting through space might need.