The theme song of an ’80s sitcom goes, “You take the good, you take the bad/You take them both and there you have/The facts of life.” The same can be said of our gut microbiome, the complex system—comprising 300 to 500 species of good and bad bacteria—that affects not just our digestive system but also has links to mental health, autoimmune diseases, endocrine disorders, cancer and more.

Over the past couple of decades, scientists have amassed a wealth of knowledge about the gut, beyond that one long input/output tube that we think of as our digestive system. It turns out, there’s a whole lot going on in there, and paying attention to what we put in our bodies can greatly affect all of our other systems, from our ability to fight off disease to our moods.

“So in our guts, we grow bacteria, good and bad,” says Samantha Coogan, director of the Didactic Program in Nutrition and Dietetics at UNLV. “That bacteria affects bloating or digestion, proper digestion, indigestion, things of that nature. So when we overconsume foods that promote bad bacterial growth, we start to see infections arise, some longer-term complications and then just overall GI [gastrointestinal] discomfort in general.”

The kind of flora that proliferates in our gut is tied directly to our diet. Fiber promotes the colonization of good bacteria, while excessive sugar and processed foods wreak havoc on the microbiome (see sidebar). And while there are long-term health implications to poor gut health, there are also immediate repercussions to an imbalance of bacteria. The most obvious and noticeable, Coogan says, is excessive flatulence and burping. An occasional occurrence is normal, but if it’s a persistent condition, it might be an indication that you should get your GI tract examined.

Another clue is your bowel movement. “It’s the one part of dietetics that nobody ever wants to talk about, but our feces and our urine tell us a lot about our health,” Coogan says. “So [don’t be] afraid to look into the toilet to see what your feces actually looks like, because the different colors and shapes will also give you an indication as to what your gut is actually performing like.”

Also, Coogan says, “How often you actually have a bowel movement is another indicator. It’s most common for people to have at least one to two bowel movements per day. There are anomalies in between—traveling, stress and the like. But if you’re going days without a bowel movement, that could also be a cause for concern.”

The long-term health implications of poor gut health and bacterial overgrowth can be serious, according to Coogan. It can potentially lead to short bowel syndrome, as well as diverticulitis, in which small, bulging pouches develop in the digestive tract, causing a lot of pain. Constant inflammation in the gut could also exacerbate autoimmune disease like Crohn’s disease or ulcerative colitis.

But the good news is that you can be proactive in creating a welcoming environment in your gut for probiotic (live bacteria found in certain foods such as yogurt) and prebiotic bacteria (beneficial bacteria that digest fibrous elements from certain types of carbs) by being discerning about the food you eat.

“They’re two different types of bacteria that work best in conjunction with each other and have a synergistic effect,” Coogan says. “Basically, they come in and try to fight off as many foreign bodies as they’re able to.”

Good gut foods

UNLV nutritionist Samantha Coogan has come up with an easy way to remember which foods are good for the gut: the three Fs and the three Ps.

Fiber-rich. These foods tend to promote bifidobacteria, good bacteria that aid the gut lining. So incorporate more fruit, vegetables, whole grains, legumes, nuts and seeds in your diet.

Fermented. Foods full of lactobacilli bacteria, beneficial for promoting gut health. These include yogurt, kombucha, sauerkraut, tempeh, kimchi and pickles.

Limiting fake foods. Artificial sweeteners and processed sugars are culprits for bloating and poor bacterial health. They promote infection and overgrowth in certain areas over a long period of time. So yes, give up that Diet Coke.

Prebiotics.Types of dietary fiber the healthy bacteria in your gut love to eat. Examples include dandelion greens, asparagus, bananas, apples and flaxseeds.

Probiotic. Though you can add probiotic supplements (available in health food stores) to your diet, Coogan says it’s easy enough to get it from a regular diet. The fermented foods mentioned above contain plenty of probiotics for your daily needs.

Polyphenols. Another great way to promote gut health, Coogan says. Find them in green tea, cocoa, grape skins, almonds, berries, broccoli and other fruits and vegetables that also fall into the fiber category.