Within our gut resides a vast ecosystem that guides countless facets of health and performance. Emerging research shows that your gut microbiota may impact many different and seemingly unrelated aspects of health and bodily function, including appetite and body weight regulation, lifespan, mood, cognition, and even athletic performance. We also know that the gut plays a role in the immune system. In fact, it is thought that over 70% of the body’s immune cells reside in the gut. Throughout life, gut microbes shape and regulate the immune system, and the immune system in turn guides the composition of the flora in the gut. We think gut microbes work a lot of their magic by generating crucial metabolites, and these metabolites can help modulate the immune system response to invading viruses. For example, one remarkable study from a couple years ago found feeding mice a high-fiber diet increased their probability of survival when the rodents were infected with influenza, and it appeared to be due to increased production of SCFAs. So, does this mean that eating lots of fiber can help protect us from getting sick? What other components of the diet might modulate the immune system? And how does aging figure into this puzzle - could maintaining a healthy gut microbiome help protect older adults, who are generally at greater risk of infection? On this episode of humanOS Radio, I speak with Lucy Mailing. Lucy has a Phd in Nutritional Sciences from the University of Illinois. Her research focused on the effects of diet and exercise on the gut microbiome and gut barrier function in states of health and disease. She recently wrote a broad overview on what we know - and what we don’t know - about the role of the gut in the immune system, as well as some ideas of what we can do to support the gut-immune axis. This is, obviously, a very important and painfully relevant topic, so we knew we had to have her on to discuss it. To learn more about how gut health affects resistance to infections, check out the interview!