Final answer:
Lactose intolerance is a genetic defect that leads to non-digestion of lactose and intolerance to milk. Individuals with lactose intolerance should avoid foods containing lactose to prevent symptoms.
Step-by-step explanation:
Lactose intolerance is a genetic defect in which the enzyme lactase is deficient or absent. This leads to non-digestion of lactose and intolerance to milk. It is not an allergy to dairy products. Individuals with lactose intolerance should avoid foods containing lactose to prevent symptoms like bloating, cramps, nausea, and vomiting.