This is the indigestible material in food. Mainly composed of cellulose from plant cell walls.
They are found in full cereals, fresh fruit fibres like lemons, oranges, mangoes and vegetables.
Importance of roughage.
•It rubs against the walls of the alimentary canal stimulating secretion of digestive enzymes and mucus to lubricate the epithelial lining.
•Roughage enhance peristalsis since as they rub against the walls of the alimentary canal, they stimulate contraction and relaxation of the muscles.
• Roughage is an absorbent; it extracts water from the alimentary canal making the fecal matter bulky and moist hence can be easily propelled by peristaltic movements. This prevents constipation.