There’s plenty of buzz about healthy bacteria in some yogurts, supplements, and other foods. The stories range from study results to scam warnings. Here, two NASM experts clear up confusion and ofer a few surprising options of foods that contain probiotics. Spoiler: They’re definitely worth eating!

Having a healthy gut or gastrointestinal (GI) tract is largely a numbers game, says Dr. Geoff Lecovin, MS, DC, ND, L.Ac., CSCS, CISSN, NASM-CPT (CES, PES, FNS) and an NASM Master Instructor, who holds master’s degrees in nutrition, exercise science, and acupuncture. In the adult gut, there are 100 trillion live microbes, also called microbiota. These bacteria outnumber our own body cells 10 to 1, but thankfully not all of these microbes are pathogenic. Some are not only beneficial but essential. (1)

When it comes to these bacteria, “you’re basically trying to outnumber the bad guys with the good guys,” says Dr. Lecovin, owner of Northwest Integrative Medicine in Redmond, Wash. “Probiotics are live food ingredients that can alter this microbiota and confer health benefits,” he says. “They are symbiotic organisms that are there to live–and to help us live.” (1, 4)

Other probiotics-related numbers are also impressive. In 2015, probiotics made up $36.6 billion of the market in terms of ingredient sales, according to Global Market Insights, Inc. And this organization expects that figure to surpass $64 billion by 2023. (9) That’s probably not a bad thing: Research shows that people in Western countries have less diversity among bacteria in their GI tract than in previous years. Antibiotic overuse, excessive hygiene, smaller family sizes, and dietary changes (fewer whole foods, more simple carbs) are some of the things that have shielded Westerners from exposure to bacteria which, it turns out, is not entirely a good thing. (2, 4)

Despite research dating back over 30 years, several misconceptions surrounding lactic acid (lactate) still exist amongst fitness practitioners and the general public (1). Common misconceptions include that it was considered a primary cause of fatigue during exercise as well as the cause of delayed onset muscle soreness (DOMS) sometimes experienced 12-to-72 hours following exercise. Furthermore, it was also incorrectly regarded as a waste product of metabolism that would impair athletic performance if it was allowed to accumulate within the muscle cell.

On the contrary, we have come to learn that lactic acid (lactate) is more friend-than-foe and actually serves as a viable energy reserve for both our aerobic and anaerobic pathways (2, 3). It is true that the accumulation of this product during intense exercise can alter muscle pH and impede muscle contraction while simultaneously activating pain receptors (aka acute muscle pain), but this issue normally resolves itself within 30 to 60 minutes following the cessation of an exercise bout (3). The DOMS experienced over subsequent hours to days has nothing to do with this metabolic by-product, but is believed to be more aligned with microtrauma occurring within the muscle fibers due to excessive loads or volumes of eccentric muscle action.