“Your body actually has more bacterial cells than human cells,” says Katie Goldberg, MCN, RDN, owner of Katie Goldberg Nutrition. Probiotics are one of the most-discussed forms of this healthy bacteria that keep our systems running at peak condition. So we spoke with nutrition experts to get the actual probiotic definition and to discover the truth about whether we need to worry about including more probiotic foods and probiotic supplements in our routine.

What Are Probiotics, Exactly?

Probiotics are beneficial live bacteria in our digestive system, or “gut.” There, they impact digestion, of course. “A healthy gut has also been linked to the prevention of many health conditions such as skin conditions like eczema, autoimmune disorders, and even obesity and diabetes, so the benefits extend far beyond good digestion,” says Sarah Gold Anzlover, MS, RDN, registered dietitian nutritionist and owner of Sarah Gold Nutrition. Research has also linked probiotics to boosted immunity, mental health, and mood. According to the Journal of Probiotics & Health, dozens more studies are in the works to see if probiotics can also impact:

Reduce the incidence of colds and the fluTreat kidney stonesPrevent gum disease and tooth issuesCombat antibiotic-resistant bacteriaFight cancer

Do I Need to Add Probiotics to My Diet?

“Most people can benefit from including probiotics in their diet, and many of us don’t get enough,” Anzlover says. “Stress, our environment, our diet, and antibiotic use can all deplete the good bacteria in our gut and results in an even greater need for consuming probiotics. If you’ve recently taken antibiotics, you may benefit from a greater dose from supplements to restore the good bacteria.” Increased consumption of probiotic foods is often recommended for those recovering from food poisoning or other infections that require treatment via antibiotics. As the name suggests, these medications kill off good and bad bacteria, says Tanya Freirich, MS, RDN, registered dietitian nutritionist and owner of Tanya B Nutrition. “Generally healthy people will also have little probiotic side effects from consuming these foods, most often a little bit of gas,” Freirich says. Eating prebiotics is just as important as consuming probiotics, “A non-digestible component found in vegetables, whole grains, and some fruits, which acts as food to foster the growth of more probiotics naturally,” Anzlover adds.

What Are the Best Probiotic Sources?

According to our nutrition pros and the Journal of Probiotics & Health, a probiotic guide for foods will include:

Yogurt Kefir Tempeh Miso Kimchi Sauerkraut Miso soup Natto (fermented soybeans)

If something has been fermented, it likely contains at least a small amount of probiotics. To get the most significant health benefits, include a mix of these foods several times weekly. “Getting a variety of these foods as well as keeping processed sugars to a minimum is key to keeping your microflora flourishing,” says Emily Henry, RDN, registered dietitian nutritionist for MealShare, a mindful eating app that connects consumers to dietitians.

Do I Need a Probiotic Supplement?

“People with compromised immune systems and pregnant women may want to avoid certain fermented foods for food safety reasons, and steer clear of probiotic supplements since supplements are not well regulated,” Anzlover says. In fact, while a 2020 report estimates that the probiotics market will be worth $76.7 billion by 2027, research published in the Annals of Internal Medicine has found that the safety of these supplements is far from guaranteed. “Check with your doctor or a dietitian that specializes in your condition to see what is safe for you and to get his or her recommendation for the healthiest probiotic supplement options,” Anzlover recommends.