Ask the Doctors: Probiotics and prebiotics are both key to gut health

Dear Doctors: I want 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?

Answer: Tthe gut microbiome refers to the trillions of microorganisms that make our digestive tracts home. These include the vast colonies of bacteria, fungi, protozoa, friendly viruses and other microbes that interact with our bodies and, in many cases, help keep us healthy.

Research keeps uncovering ways that the gut plays a role in health, including how it affects the immune system, blood-sugar regulation, the cardiovascular system, cholesterol, weight and even mental health.

With some simple lifestyle choices, you can improve your gut health. To understand how, we should define two important terms — the probiotics you mention and prebiotics, equally important to the gut microbiome.

Probiotics refers to the good microbes living in our guts. A wide variety of probiotics is available as dietary supplements and also can come from foods such as yogurt, kefir and naturally fermented food and drinks. The jury is out on whether probiotic supplements actually help gut health.

Perhaps more important are prebiotics. These are indigestible carbohydrate found in fiber-rich foods including fruits, vegetables, seeds, beans and legumes. Prebiotics pass through the digestive system to the colon largely intact. They provide a food supply for the probiotics living in our gut. So it’s important to eat a wide range of fresh fruits, vegetables and other prebiotics.

In addition to what you do eat, gut health depends on steering clear of certain foods. Recent studies have shown eating a lot of simple carbohydrates can tip the balance of gut bacteria to microbes associated with low-grade inflammation. That’s the opposite of what you want to achieve. The occasional sweet won’t wreak havoc, but people who regularly eat a lot of sugar or highly processed foods should rethink that.

Studies also have found that the denizens of our gut microbiome respond positively to exercise. A 2017 study linked 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.

Dr. Eve Glazier is an internist and associate professor of medicine at UCLA Health. Dr. Elizabeth Ko is an internist and assistant professor of medicine at UCLA Health.