Lactose intolerance is the inability to digest dairy products because of the absence of which enzyme?

• A. Amylase
• B. Lactase
• C. Protease
• D. Lipidase

Answer: (B)

Lactose intolerance occurs when the enzyme that normally splits lactose into simpler sugars is missing. Lactose, the sugar in milk, must be cleaved by lactase in the small intestine to become glucose and galactose, which can be absorbed. Without lactase, lactose remains intact, draws water into the gut, and is fermented by bacteria, causing symptoms after dairy consumption. Amylase digests starch, protease digests proteins, and lipase digests fats, so those enzymes don’t address lactose digestion.