First things first: Let’s define these food groups. Fiber is a type of complex carbohydrate found exclusively in plants that isn’t broken down in the digestive tract and, therefore, helps with satiety, digestion, blood sugar balance, healthy bowel movements, and microbial balance (i.e., good versus bad gut bugs). Fiber-rich staples include buckwheat, barley, kale, broccoli, lentils, and more—you can find a full list here, as well as our favorite fiber supplements.
Fermented foods, on the other hand, are created through fermentation (duh), in which components of foods, like the natural sugars, are broken down by yeast and bacteria and result in food chock-full of probiotics (aka, the good bugs). Some examples include kombucha, kimchi, sauerkraut, miso, and yogurt, plus others.