Fiber is a term used for several plant materials that your body can’t digest. It is a polysaccharide (multiple molecule sugar) carbohydrate, but unlike starch and sugar, fiber cannot be broken apart by your digestive enzymes. A healthy diet needs a variety of fiber sources. Fiber promotes a healthy digestive system, and can reduce cholesterol levels. Healthy daily fiber intake for a 2,000-calorie-a-day diet should average about 30 grams. Unfortunately, most Americans get only half of what they need.