Dietary fiber , also known as roughage , includes the parts of plant foods your body can’t digest or absorb. Unlike other food components, such as fats, proteins, or carbohydrates — which your body breaks down and absorbs — fiber isn’t digested by your body . Fiber is however an important source of food for our gut bacteria (microbiome). Sources of fiber include: Whole grains : Oats, brown rice, quinoa, and whole wheat. Legumes : Split peas, lentils, and beans. Vegetables : B