When astronauts stay in space for extended periods, they get bombarded with radiation. This accumulated radiation not only damages tissues. It will also damage the helpful bacteria in our intestines, our gut microbiome.
Radiation, unhealthy eating habits, and antibiotics will kill large colonies of gut bacteria. That is why seemingly harmless antibiotics can do more harm than good in healthy people. Probiotics have been prescribed for decades to restore the balance after a course. Returning your microbiome to its proper functioning can take months and in some case years. It turns out there is a much more powerful and quick acting method.
If we do a cell count, humans are mostly composed of microbes situated in our intestine. They digest the food for us, cultivating molecules our cells can actually use. They constantly interact with the inner lining of our intestines which is only a single cell wall thick. It acts both as a gate and defense system to let good molecules into our bloodstream and keep bad molecules out. Via the nervus vagus a direct connection exists between the gastrointestinal tract and the brain. It is no surprise then that at the other side of that wall, the majority of cells of our immune system are stationed, going into overdrive whenever potentially dangerous molecules are detected. In trying to prevent any overburdening of our immune system, it is important to keep this lining in good health. When it breaks down we have a condition called ‘leaky gut’, the leaking of harmful molecules into our bloodstream. Often passed down as pseudoscience mere decades ago, researchers are finding more and more workable clinical applications of research based on this insight.
Mind controlling bacteria
When patients undergo a fecal transplant (FT), literally an extraction from the colon of one person injected in the colon of a recipient, the composition of the bacteria in the recipient’s colon changes. Once beyond the ick-factor of having to ask a family member or stranger to donate part of his inner garden, the procedure can be life-changing. Fecal Transplants have even resulted in dramatic changes in behavior.
According to examples given in a book by Dr. Steven Gundry, The Longevity Paradox, How to Die Young at a Ripe Old Age (2019),* when researchers performed a transplant in mice models, from obese into skinny mice, the latter get fatter on an identical diet. In the 1930’ies, depressed institutionalized patients had enema’s to clean their colon and received enemas from normal happy subjects. Two-thirds of these patients lost all symptoms of depression. Finally, when taking bacteria from young animals guts and introducing them in the intestines of old animals, the latter become young again in the sense that their cells will get younger, they get more youthful energy and extend their lifespan by about 30%.
Not only do bacteria seem to control our appetite or cure our depression** they potentially hold the key to the fountain of youth in animals and humans.
Dr. Steven Gundry is not alone in signaling the importance of this research. As it turns out, modern science is rediscovering that Hippocrates (ca 460–370 BCE) was indeed correct when pointing out that ‘all health starts in the gut’. Already used in multiple clinical trials, FT is turning out to become a very powerful method in the toolkit of future medicine.
Space travel turns out to be very taxing on our microbiome, and preventative paths are being followed to reduce the impact where we can. This is especially important on long-duration deep space missions, where astronauts are no longer protected by Earths’ magnetosphere.
One way to do it is to have astronauts wear water jackets or composite plastic jackets with a high hydrogen content (a good radiation blocker). These would be thicker around the brain and gut. The downside is they impede movement somewhat. In the future, when the launch cost of materials erodes and mass allowances increase, a more ideal solution would be to shield habitats with thick water walls, allowing a shirt sleeve approach to the problem. While this works well -on Earth it is used in pools of nuclear power plants to keep radiation workers safe from the radiation of fuel rods-, for now, it is too costly to launch large volumes of water into orbit. As a result, the best current option is to create small radiation shelters. In case of a radiation emergency, (increased solar activity) astronauts gather all mobile materials around a small area and hide inside of it. While this is a suboptimal solution it does help in reducing a good fraction of the radiation dose.
On the curative side, we are becoming convinced that remediating damage to the microbiome might become a helpful strategy. Stools collected before the mission could be stored onboard in a small dedicated radiation shelter, keeping the colonies in perfect health.
After a radiation event, or in the case of reduced health, an astronaut on a long duration Deep Space mission could be inoculated with his own stool and given time, recover to better health. This implies that when humans will finally settle in Martian colonies, we will also have to plan for and build small Martian colonies of essential microbes. Another potential nightmare for the planetary protection crowd, the approach seems to be dictated by our gut.
Exploding rockets, suffocation, radiation, fecal transplants. We can only conclude that to be active in space travel you need guts.
*Dr. Steven Gundry, MD, FACS, FACC, is the director of the International Heart and Lung Institute in Palm Springs, California, and the founder/director of The Center for Restorative Medicine in Palm Springs and Santa Barbara. He is the author of The Longevity Paradox, How to Die Young at a Ripe Old Age (2019).
** Evrensel A, Ceylan ME. The Gut-Brain Axis: The Missing Link in Depression. Clin Psychopharmacol Neurosci. 2015;13(3):239–244. doi:10.9758/cpn.2015.13.3.239