Probiotics, live bacteria found in fermented foods, can do your gastrointestinal tract a world of good. “Consuming foods high in probiotics can help you maintain good gut health and support a diversity of bacteria in your gut,” says professor Dhyanesh Patel, M.D. Upping your intake of probiotics may lead to a stronger immune system and improved digestion. Good sources include yogurt, kefir, kimchi, sauerkraut, miso, tempeh, and kombucha. There’s also a market for probiotics in capsule form, but it can be hard to know which one is right for you. “This is a field where one size doesn’t fit all,” says Patel. Start with probiotic-rich foods, and if you’re still not happy with how your digestive business is going, talk to your doctor about which probiotics might work for you.