Why starch cannot be used by the body until has been digested?

Starch cannot be used by the body until it has been digested because it is a complex carbohydrate that must be broken down into simpler sugars before it can be absorbed into the bloodstream. This process of digestion begins in the mouth when salivary amylase breaks down starch into smaller dextrin molecules. Once swallowed, the stomach secretes hydrochloric acid and pepsin, which further break down dextrins into smaller oligosaccharides. Finally, in the small intestine, pancreatic amylase, maltase, and sucrase break down the oligosaccharides into monosaccharides (glucose, fructose, and galactose) that can be absorbed into the bloodstream. Without digestion, starch would pass through the digestive system without being absorbed, and the body would not receive the nutrients it needs.