Head to the store, pick up a bottle of Kefir, and start drinking it daily, says Dr. Kris Clark, director of sports nutrition at Penn State. A fermented liquid yogurt-type of drink containing live cultures, Kefir can be used instead of milk on cereal, as part of a smoothie, or consumed straight from the bottle. "No product on the market exists with higher levels of probiotics — 12 or more depending on the product chosen," Clark says. "Probiotics are key ingredients for promoting optimal gut health, the headquarters of immune function."
Studies have shown that kefir can diversify your gut bacteria, fight off bad bacteria, and boost your immune system. It's also packed with nutrients (including B vitamins, calcium, and protein) that can strengthen your bones and improve digestion (especially if you're lactose intolerant). It's no surprise that kefir is said to derive from the Turkish word keif — or "good feeling."
But if the drink isn't to your taste, there's still ways you can maintain a solid microbiome. "Kefir, pickles, yogurt, and sauerkraut all have healthy bacteria to help your gut," says Pegha Jalali, a registered dietitian at NYU Langone Medical Center.