The primary dietary fiber known for its benefits to digestion is "cellulose." Cellulose is a complex carbohydrate found in the cell walls of plants and is a major component of dietary fiber. It is not digestible by human enzymes, which means it adds bulk to stool and aids in the movement of food through the digestive tract, promoting regular bowel movements and preventing constipation. High-fiber foods, including fruits, vegetables, whole grains, and legumes, are rich in cellulose and other types of fibers, offering additional health benefits such as improved gut health and reduced risk of chronic diseases.