Gut microbiome – interior digestive ‘city’ and how to navigate it

Over the last 15 years medical researchers have discovered that digestive health matters far more than we used to think. The gut microbiome is becoming a dominant field in medicine—how we modify it, how we keep it healthy, and how it affects not just the gut, but every organ and system in your body.

City inside your gut

When we talk about the “gut,” people think of the stomach. But in my world, when we say “gut,” we’re talking about the entire gastrointestinal (GI) tract, which includes all the organs of the digestive system—all the way from gums to the end of the line.

You can think of your gut microbiome as a city. There are millions of microorganisms living inside the GI tract—bacteria, fungi, archaea, viruses, and bacteriophages—and they must function together and in relationship to their host (you). As in a city, you need diversity of occupations for the whole system to work well. If a certain type of bacteria with a particular function dies, there are problems throughout the whole system. This is in part why there’s rarely a simple solution when a person is experiencing digestive problems. The GI system is astoundingly complex.

There are many products on the market claiming to help with gut health—supplements, probiotics, kombucha, fiber, etc. When I see patients with gut problems, I wish it were as simple as telling them to take a probiotic and wash it down with kombucha, but it’s not. There is little to no evidence that such products do any good. Probiotic research has been going on for decades, and we really haven’t found any breakthroughs.

The only things we know for sure make a positive impact on gut health are quite simple: a healthy diet, exercise, avoid medications you don’t really need, and potentially intermittent fasting.

Gut and immune health

After bone marrow, your gut is the second biggest immune system in your body. A lot of the immunotherapies being studied now are focused on gut health because many of the diseases that affect immunity also affect and are affected by the gut. COVID-19 is a prime example. There’s research indicating that the health of a person’s microbiome may influence the severity of their COVID-19 symptoms, as well as the strength of their body’s immune response to fight the infection.

I expect in another decade or two, gut health will be as commonly discussed as heart health. I’m delighted to be on the forefront of some of this research. We have a lot to learn. We’re studying millions of bacteria, each with its own set of genes. And we’re trying to figure out how to modify them, so people feel good without side effects. It’s a tricky and exhilarating challenge.

ALI REZAIE, M.D., M.SC., F.R.C.P.C., is medical director for the GI Motility Program at Cedars-Sinai Medical Center in Los Angeles. He is one of Healthnetwork Foundation’s Service Excellence Award recipients in recognition of his superb patient care.