Now more than ever, I wish I had a megaphone and release. It’s a vicious cycle, but it can be broken with attention could stand on a table to shout to the world about the importance of gut health. As a gastroenterologist, Georgetown Med 2006 alumnus, and author of Fiber Fueled: The Plant-Based Gut Health Program, I’m happy to see this forgotten organ finally get some of the attention it deserves. But clearly there is a lot of room for improvement, when most Americans think of bone broth and probiotics as the backbone of a healthy gut. (They’re not!)
Let’s start with the basics. Inside each of us is around 39 trillion microbes. Mostly bacteria but also fungi, sometimes parasites, and my personal favorite—the archaea. These microbes actually outnumber our human cells—yes, you are less than 50 percent human—and they account for 99.5 percent of our genetic code.
Although these microbes are invisible, they are as alive as you and I and they’ve been a part of human history from the very beginning. Through three million years of coevolution, we’ve grown to trust these microbes with essential functions in our health. They are critical to digestion and allow us access to the nutrients in our food. They strongly influence inflammation and immunity. Did you know that 70 percent of our immune system resides in our gut? Through bioactive molecules, these microbes affect our metabolism, including our weight balance, insulin sensitivity, and satiety. They regulate estrogen and androgen balance. They affect our mood and cognition. There’s even evidence to suggest that they control our cravings. In short, they are powerful!
Consider the role of these microbes in the era of COVID-19. Our immune system is our shield against this virus. We need it optimized to defend us, and there are numerous studies showing a direct connection between our gut microbes and immune system. When they are strong, our immune cells are strong. When they are disturbed, which we call dysbiosis, then our immune cells are disturbed as well. You’ll find dysbiosis present in all cases of autoimmune disease.
The same is true with our mood. In times of stress, the brain releases corticotropin-releasing hormone (CRH), which is known to have an adverse effect on our gut microbes. Ninety percent of the serotonin and fifty percent of the dopamine in our body are produced in the gut. When the gut microbes are negatively affected, they alter the balance of serotonin, dopamine and other neurotransmitters, and their precursors. The result can be anxiety and fear, which leads to increased CRH to the gut microbes.
Sadly, we have done more than just neglect our little friends. The changes in our diet and lifestyle over the last century have been an all-out assault on their health, and we are exacerbating these issues by doubling down on our unhealthy habits under the stress of COVID-19. We’ve traded real food that’s derived from the dirt for a diet of mostly processed, fried, or hormone- and antibiotic-laden foods. We strip out the fiber, the preferred food of our microbes, and replace it with preservatives, emulsifiers, colorants, and other chemical additives. We’ve stopped moving and instead spend our days at a desk and our nights on a couch inside a hyper-sterile human-built edifice. We’ve shunned “early to bed, early to rise” and instead spend all night on Twitter, with the blue light from our tablet disrupting our circadian rhythm. My friends, we have transitioned into an overfed, undernourished, and hyper-medicated life that is unfriendly to our gut microbes.
So what’s the solution? It’s rather simple. We need to get back to the basics by restructuring our diet and lifestyle. There are no shortcuts, no supplements that take us from a C- gut to an A+. Instead, we should form healthy habits. When we do this, small changes start adding up to massive results. Exercise, a good night’s rest, human connection, and time spent outdoors are all important to the health and balance of our gut microbes.
But the most important thing is the food we eat. Researchers running the American Gut Project, the largest study to connect diet and lifestyle to the health of our microbiome, found that the single most powerful predictor of a healthy gut is the diversity of plants in our diet. Why’s that? All plants contain fiber. In fact, they contain unique types of fiber. Not all fiber is created equal! There’s tremendous biochemical variety in this highly complex category. Our gut microbes love fiber, but they are picky eaters. Not all microbes eat the same fiber: some microbes prefer black beans while others feast on kale. So for us to feed all of our gut microbes, we must eat a diet with as many varieties of fruits, vegetables, whole grains, seeds, nuts, and legumes as possible.
It’s fascinating to consider that the key to human health comes from something that isn’t even human. We really do need these microbes for optimal digestion, immune and metabolic health, and hormonal and mood balance. Now more than ever, we should be making choices to nurture and support these microbes so that if and when we need them, they’ll be there for us.
