Which statement about carbohydrate digestion in the mouth is true?

Which statement about carbohydrate digestion in the mouth is true?

• A. Carbohydrate digestion occurs only in the mouth
• B. Carbohydrate digestion begins in the mouth due to alpha amylase from salivary glands
• C. Carbohydrate digestion begins in the stomach due to pepsin
• D. Carbohydrate digestion is completed before entering the small intestine

Answer: (B)

Carbohydrate digestion begins in the mouth because salivary alpha-amylase from the salivary glands starts breaking down starch right as you chew. This enzyme cleaves internal alpha-1,4 glycosidic bonds, producing smaller sugars like maltose, maltotriose, and dextrins. However, this digestion is limited in the mouth because the acidic environment of the stomach inactivates salivary amylase, so most carbohydrate digestion does not complete there. The real work continues in the small intestine with pancreatic amylase and brush-border enzymes that finish breaking down disaccharides into monosaccharides. Pepsin in the stomach digests proteins, not carbohydrates, so it doesn’t contribute to carbohydrate digestion. Therefore, the true statement is that carbohydrate digestion begins in the mouth due to alpha amylase from the salivary glands.

Carbohydrate digestion begins in the mouth because salivary alpha-amylase from the salivary glands starts breaking down starch right as you chew. This enzyme cleaves internal alpha-1,4 glycosidic bonds, producing smaller sugars like maltose, maltotriose, and dextrins. However, this digestion is limited in the mouth because the acidic environment of the stomach inactivates salivary amylase, so most carbohydrate digestion does not complete there. The real work continues in the small intestine with pancreatic amylase and brush-border enzymes that finish breaking down disaccharides into monosaccharides. Pepsin in the stomach digests proteins, not carbohydrates, so it doesn’t contribute to carbohydrate digestion. Therefore, the true statement is that carbohydrate digestion begins in the mouth due to alpha amylase from the salivary glands.