Fermented foods: These are probiotic-rich foods that have been naturally preserved by bacteria, so they help the beneficial bacteria in your gut to grow. That leaves less room for the kinds of harmful bacteria that can cause illness.

Fermented foods include:

• Yogurt: Look for the phrase “live and active cultures” on the label. Even if you have lactose intolerance, there’s a good chance you can handle yogurt, since the bacteria also ferments and breaks down the lactose.
• Kefir: It’s a thick, tangy, fermented milk drink (pronounced kuh-FEAR) that’s been around for thousands of years. Look for it in the dairy aisle in plain and flavored varieties, and drink it straight or in smoothies.
• Miso: This thick paste made from soybeans and grain has a savory “umami” flavor. Stir it into salad dressings, marinades, and soup stock.
• Tempeh: Like tofu, this is made from soybeans, but it’s also fermented. It’s firmer and chewier than tofu and a great source of protein. Cut it into slices to bake or stir-fry.
• Sauerkraut: It naturally contains healthy bacteria. Check labels for simple products that contain only cabbage and salt.

Prebiotic foods: These plant foods actually work like “food” for probiotics, helping those good bacteria to grow and flourish in your gut. Foods that naturally contain prebiotics include:

• Onions: Whether you eat them raw or cooked, they help feed healthy gut bacteria.
• Bananas: Very ripe bananas are sweeter, but less ripe bananas will have more prebiotic power.
• Sweet potatoes: They work as a prebiotic and are a great source of fiber.
• Apples: They contain pectin, a starch that acts as a prebiotic. (Bonus: They’re one of the most filling fruits, so they’re good at satisfying hunger.)
• Chicory root: You can spot this ingredient on food labels. It’s often added to foods marketed as healthy or low-carb to add fiber. (Note: Some people can be sensitive to chicory root – learn more here.)

• Beans: They’re a high-protein swap for meat and deliver loads of fiber.
• Raspberries: All berries are good sources of fiber, but raspberries are one of the highest-fiber fruits around. Buy frozen if fresh are hard to find.
• Seeds like flaxseed and chia seeds: Add these fiber-rich seeds to oatmeal and smoothies. (Just be sure to choose ground flaxseed to get the benefits.)
• Oats: No matter what kind you choose – old-fashioned, quick, or steel-cut –they’re fiber-rich and also work as a prebiotic.
• Whole grains: For more fiber, trade white rice for brown, white pasta for whole-wheat, and egg noodles for barley noodles in soup.