Final answer:
The symptoms of bloating, diarrhea, and dehydration after consuming dairy suggest a deficiency in lactase, leading to lactose intolerance.
Step-by-step explanation:
Individuals that present with bloating, diarrhea, and dehydration after consumption of dairy products are most likely deficient in lactase. This condition, known as lactose intolerance, occurs when the absorptive cells of the small intestine do not produce enough lactase enzyme to digest lactose, the sugar found in milk. As lactose is not properly digested, it moves to the large intestine where it is fermented by bacteria, causing symptoms such as gas, abdominal cramps, and diarrhea. Avoidance of lactose or taking lactase supplements can alleviate these symptoms.