This spicy, robust fermented cabbage is a traditional Korean condiment. Like sauerkraut, it delivers lots of good bacteria right to your gut. Kimchi is usually made with onions, which act as a prebiotic feeding the healthy bugs in your intestine, says Rumsey. And garlic is also a popular add-in, further cranking its prebiotic muscle. Just make sure you go for the unpasteurized kind, since good bacteria are killed off during the pasteurization process.