Cellulose is a kind of fiber, which is a dietary necessity because of the role it plays in digestion, explains Mayo Clinic. Fiber helps a person create healthy stool and maintain bowel health. It also helps control blood sugar levels, lower cholesterol levels and avoid overeating.
Most people do not eat enough foods that are naturally high in fiber, says Mayo Clinic. Fiber increases the size and weight of stool and softens it, which helps people avoid constipation or loose, watery stool. It can lower the risk of hemorrhoids and colon diseases. Soluble fiber lowers "bad" cholesterol levels and may have other healthy benefits like reducing blood pressure and inflammation. High-fiber foods take more time to chew so overeating is less likely, and a high-fiber meal lasts longer and feels larger.
Other food components like fats, proteins and carbohydrates are absorbed and used by the body, but fiber passes through the digestive system essentially intact, notes Mayo Clinic. Legumes, whole grains, vegetables and fruits are good sources of fiber. The Institute of Medicine recommends men under 50 to consume 38 grams of fiber daily and men over 50 to consume 30 grams. Women under 50 need 25 grams a day, and 21 grams is recommended for women over 50.