Lactase is a digestive enzyme that catalyzes the break down of lactose, a sugar found in milk. Lactase functions best within limited ranges of both temperature and pH in its given environment, making it dependent on both factors for it to perform this essential reaction. If lactase is rendered nonfunctional because of temperature or pH extremes, the breakdown of lactose stops. When this breakdown ceases in the human body due to insufficient or ineffective lactase, the result is lactose intolerance.
