Final answer:
Lactase production ceases in adulthood for lactose intolerant individuals due to a deficiency of the enzyme lactase.
Step-by-step explanation:
Lactase production ceases in adulthood for individuals who are lactose intolerant. Lactose intolerance is a condition where the body does not produce enough of the enzyme lactase, which is needed to digest the milk sugar lactose. This condition is more common in certain populations, such as Asians and adults of European descent, and can result in symptoms like diarrhea and vomiting when consuming milk.