There are plenty of options, but fermented foods are one potent natural source of probiotics. Here, learn why fermented foods are so beneficial and which pack the biggest probiotic punch. But before you read on for our favorite fermented foods, it’s important to understand that if you haven’t been eating them already, you need to introduce them slowly, says Ali Miller, R.D., L.D., CDE, author of The Anti-Anxiety Diet. Probiotic foods are powerful and can cause some GI distress if you go from zero to 100 too quickly. Your GI tract can also get a boost from the benefits of fermented foods. One study found that highly fermented foods increased microbiome diversity and decreased inflammatory activity in the gut2. “Kombucha is a unique probiotic food because of its SCOBY culture,” says Miller. “Its SCOBY includes saccharomyces boulardii, which has many benefits for digestion and dermatitis.” While experts agree3 that there need to be more studies on humans to determine the health benefits of kombucha, some research suggests that other components of kombucha, like the polyphenol compounds from tea, are linked to a variety of health benefits4, including reduced cholesterol levels, decreased blood sugar levels, possible reduced risk of some cancers, and improved liver and GI functions. Kombucha is also high in glucaric acid, which provides important support for detoxification5. “If you’re counting on kombucha to repopulate your gut with beneficial bacteria, I think it’s necessary to upgrade your fermented food regimen,” Ellen Vora, M.D., holistic psychiatrist, told mbg. “Add A-list ferments like sauerkraut and kimchi along with starchy tubers like sweet potato to really shift your gut flora.” “Kefir has a larger variety of beneficial probiotics compared to yogurt, so this will help promote healthy digestion and microbiome health,” William Cole, D.C., IFMCP, functional nutrition expert, told mbg. It also contains B vitamins, vitamin K2, and tryptophan—an essential amino acid that’s a precursor to mood-stabilizing serotonin. Some pickled vegetables, like sauerkraut and lacto-fermented pickles, are also fermented. Even better, soy foods of all varieties contain omega-3 fatty acids, which can reduce the risk of cardiovascular disease11 and improve brain health12. And soy’s isoflavone phytochemicals may help prevent postmenopausal bone loss13 and some cancers14. Yogurt is also high in protein—Greek yogurt can have 18 to 20 grams per serving—and calcium, which makes it a wise choice for maintaining balanced blood sugar and boosting bone health.