Over the last few years, there's been a lot of buzz about probiotics, the so-called "good" bacteria that reside in the gut. They're believed to offer a wide range of health benefits, from a robust immune system to improved digestion. Not long after we started hearing about probiotics, prebiotics became a thing. Prebiotics are "most soluble fibers and resistant starches" that those good gut bacteria rely on for food, says Emilie Vandenberg, a registered dietitian at the Ohio State Universit...