This Is the #1 Predictor of a Healthy Gut Microbiome, According to a GI Doctor

Research shows that maintaining a well-balanced gut microbiome is an integral part of both short- and long-term health. After all, a properly functioning gastrointestinal system is the foundation for the health of your entire body, with the ability to impact everything from your cardiovascular system and chronic disease risk to your mood, memory, and cognitive functioning.

“There are a large number of medical conditions that have been associated with damage to the gut microbiome,” says Will Bulsiewicz, MD, a gastroenterologist and New York Times bestselling author of Fiber Fueled and The Fiber Fueled Cookbook. This includes digestive disorders, immune disorders, and hormonal disorders (think everything from PCOS to depression and anxiety).

According to Dr. Bulsiewicz, there is one action we can all be taking to significantly move the dial towards a healthy, well-functioning digestive tract—no fancy supplements or complex dietary changes required. Ready for it? The key to improving your gut microbiome, he says, lies in a thorough trip through the produce aisle. There is no one magical superfood here to save you from your digestive woes: The solution comes down to a question of diversity. Put simply, the more different types of plants you eat, the better the health of your gut microbiome.

Microbiome 101

The term microbiome tends to get thrown around pretty casually in the wellness world, so if you’re wondering what it exactly means, you’re not alone. “The microbiome is a collection of invisible microbes that are a part of our body,” says Dr. Bulsiewicz. These microbes are found on your skin, in your mouth, and in your large intestine (also known as your colon). They’re highly concentrated in your colon—38 trillion, to be exact—and are intimately intertwined with your overall health.

“The bacteria in your microbiome (aka, your gut flora) are not just passengers; they’re actually trying to help you thrive and be the healthiest human possible,” says Dr. Bulsiewicz. He explains that the microbes aid greatly in digestion, which is the process of breaking down the food you eat into useful nutrients for your body. “But in addition to our digestive health, research shows that the microbiome is also deeply connected to our energy levels, immune system, hormones, mood, brain health, and even the expression of our genetic code,” Dr. Bulsiewicz says. Given the important responsibility that the microbiome plays in our overall functioning, it makes sense that when the microbial system is not in balance, our overall health can suffer.

What it means to have a healthy gut microbiome

You chug water all day, eat plenty of fiber, and load your plate with sauerkraut, but how do you actually know if you have a healthy gut microbiome (or lack thereof)? According to Dr. Bulsiewicz, because we rely on the microbes in our large intestine to break down our food, the first sign that something is amiss is digestive distress. This could manifest as gas or bloating, abdominal discomfort, diarrhea, or constipation. Gut imbalances may also cause you to feel more fatigued than usual or notice something off with your bowel movements (such as bloody stools or straining).

A person with a well-balanced gut microbiome, on the other hand, doesn’t generally suffer from digestive pain in their daily life, and is able to eat a variety of foods without restriction. (The exception, of course, is for those who have a food allergy, sensitivity, or other condition—Dr. Bulsiewicz affirms that it’s perfectly possible to avoid certain food groups and still have a health gut.) He is also quick to point out that even if you have a healthy microbiome, you could still deal with some distressing symptoms if you, say, chugged five shots of espresso or drank an entire bottle of wine. But for the most part, people with a strong gut microbiome can follow their regular eating habits and not have to worry too much that they’re going to suffer a consequence (again, being mindful of food allergies and intolerances).

To improve the health microbiome, focus on the numbers

If you’re feeling like your gut health may be less than stellar, there is good news: Important clinical research has helped us uncover what the top predictor is for a healthy gut microbiome, and it’s something that you can take control of. As part of the American Gut Project, researchers studied over 11,000 people from around the world and looked at the intersection between diet and lifestyle and the health of a person’s gut microbiome. What they uncovered through their analysis of all the data was that there was one clear indicator of a healthy gut microbiome, and that was the diversity of plants in their diet.

Dr. Bulsiewicz explains that every single plant has a unique blend of fiber and prebiotics, which feed the microbes that live in your digestive tract. “These microbes are as alive as you and I are. It’s easy to dismiss them, because you and I can’t see them. But they they need to eat, and they have their own unique dietary preferences,” he says. The more types of plants you consume and the wider the range you embrace in your diet, the more and different types of fibers and polyphenols you get. This means you’re providing more food for the diverse species of microbes, which helps (literally) empower them to work hard and better support your digestive system.

So… what exactly is ‘diverse’?

According to Dr. Bulsiewicz, the fact that so many people struggle with an unhealthy gut really stems from the fact that most are not eating nearly enough plants overall. “The average American’s diet is only 10 percent plant-based, and 75 percent of the calories we consume that do come from plants are coming from only three plants in our diet: Wheat, soy, and corn,” he says.

What researchers for the American Gut Project identified was that no matter what diet was followed, participants who ate more than 30 different plant types per week had the healthiest gut microbiomes. 30 may sound like a lot, but Dr. Bulsiewicz recommends “gamifying” the process to eliminate some of the overwhelm. “Assign plant points where every new plant is one point,” he says. “Then try putting a sheet of paper on the refrigerator and keeping track of how many plant points you get at every meal. And play against your family members or your kids!” A little healthy competition to get the whole fam excited about healthy eating? We’re in.

Once you start making an active effort to throw an extra handful berries, banana, and greens in your smoothie or put together a soup with a whole medley of vegetables, you’ll find that it’s a lot easier than you think to hit your target. It just requires a little effort upfront to stray beyond just your tried-and-true romaine lettuce, almonds, and brown rice. Stocking up on new varieties of produce, grains, legumes, and seeds is going to add tons of new and nuanced flavor to your meals, too—major plus. Exploring what’s in season at your local farmers market can also be a fun way to explore new ingredients you might not have put on your grocery list.

Keep in mind that this is not meant to be restrictive in any regard. In fact, a well-balanced microbiome requires quite the opposite: It’s all about more. Focus on adding new and different plants in to your diet, rather than taking anything out, to help your digestive system—and overall health—thrive.

Bottom line? No matter how you choose to start improving the health of your gut microbiome, you’ll be thanking yourself for years to come.