ASK THE DOCTORS

Both probiotics and prebiotics key to healthy gut

Dear Doctor: My big New Year’s resolution was to get my gut into better shape. I’m not talking about a flat stomach — after having three kids, that ship has sailed — but about the gut microbiome. Do I need to take probiotics?

Dear Reader: Considering the abundance of foods and drinks with which many of us celebrate the weeks between Thanksgiving and Jan. 1, the new year is a logical and appropriate time for a gut reset. And, yes, we’re talking about the gut microbiome here, which is the collection of trillions of microorganisms that call our digestive tracts home. These include the vast and varied colonies of bacteria, fungi, protozoa, friendly viruses and other microbes that interact with our bodies and, in many cases, help to keep us healthy. Research into the microbiome continues to uncover the many ways in which gut health plays a role in general health, including how it affects processes as varied as the immune system, blood sugar regulation, the cardiovascular system, cholesterol, weight and even mental health.

The good news is that, with several simple lifestyle choices, you can improve your gut health. To understand how, we should define two important terms — the probiotics that you mention and another equally important piece of the gut microbiome puzzle, prebiotics. Probiotics is the word we use to describe the good microbes living in our guts. A wide variety of types and strains of probiotics are now available as dietary supplements, and in food sources such as yogurt, kefir and naturally fermented foods and drinks. The jury is still out as to whether or not probiotic supplements are actually helpful in achieving and maintaining gut health.

Perhaps more important are prebiotics. These are a type of indigestible carbohydrate that are found in fiber-rich foods, including fruits, vegetables, seeds, beans and legumes. Prebiotics pass through the digestive system and arrive in the colon largely intact. There, they provide a food supply for the all-important probiotics living in our gut. In order to support your microbiome, it’s important to eat a wide range of fresh fruit, vegetables and other prebiotics.

In addition to what you do eat, gut health depends on steering clear of certain foods. Unfortunately for those of us with a sweet tooth, recent studies have shown that a high intake of simple carbohydrates in the diet can tip the balance of gut bacteria to specific types of microbes associated with lowgrade inflammation. That’s pretty much the opposite of what you’re trying to achieve. The occasional sweet treat won’t wreak havoc on the gut, but people who regularly eat a lot of sugar or highly processed foods need to rethink their diets.

Gut health isn’t all about food. Studies have found that, just like our hearts, bones, muscles and mood, the denizens of our gut microbiomes respond positively to exercise. A study published in 2017 found a link between exercise and the bacteria that support weight loss. Add in adequate sleep and managing stress, and you’re on your way to a healthier gut in 2021.

(Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D., is an internist and assistant professor of medicine at UCLA Health.)