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Space: a gut check in more ways than one

People often take or eat probiotics to help regulate their digestive health, but what happens when we send probiotics to space for three years? UF/IFAS researchers hope to find out.

NASA is planning several Mars missions that would require humans to be away from Earth for about three years. This includes the time to get to Mars, time on Mars and the time traveling back to Earth. Maintaining the health of astronauts on these long-term missions is critical and digestive health plays a major role in that.

Probiotics are living microorganisms that help maintain a healthy digestive system. With the help of UF/IFAS researchers, NASA is exploring the idea of adding probiotics to astronauts’ diets for long-term space flight.

“With long term missions on the International Space Station where astronauts spend several months to a year in space, researchers have found that astronauts undergo microbiome changes to their intestinal system,” said Wayne Nicholson, UF/IFAS microbiology and cell science professor. “In spaceflight, the gut microbiome undergoes alterations in overall population density and in the relative abundances of particular bacteria.”

“Human cells make up only half of the body’s total cell count; the other half are microbes,” he said. “These microbes are incredibly important to human health. As we know, on Earth, when people have problems with their intestinal flora, they can take probiotics to improve their gut health. There has been very little research done on the gut health of astronauts, so we are exploring different probiotics that they could take on this three-year trip to keep their gut health in shape.”

In Nicholson’s lab, researchers study how bacteria respond to strange environments like space and other planets, including Mars.

“The second challenge for us to consider is that NASA plans to take all of the items the astronauts need for the entire three-year mission with them on the trip,” Nicholson said. “They do not plan to grow materials on Mars for this mission, so everything packed has to last for three years. We have to understand if the three-year shelf life is possible for probiotics.”

One of the major factors to consider that may impact the probiotics is radiation from the space environment. This project takes three common commercially available probiotics and exposes them to a simulation of radiation exposure they would encounter on a trip to Mars.

After exposure at the NASA Space Radiation Lab, UF/IFAS researchers will measure the probiotics’ ability to survive the trip to Mars and passage through the gut once consumed by astronauts. To be effective, the probiotics must survive exposure to stomach acid and make it from the small intestine to the large intestine where they live. The radiation exposure may compromise their success.

“While we do not have the results of this experiment yet, I suspect that the radiation doses on a trip to Mars and back are not so severe that freeze-dried bacteria, like those found in probiotics, will be killed,” Nicholson said. “Humans are susceptible to much lower radiation doses than bacteria.”