Some individuals do not produce sufficient amounts of the enzyme lactase to digest the sugar lactose, present in milk and dairy products, and are referred to as “lactose intolerant”. Lactose is a disaccharide, which must be broken down by lactase into its constituent monosaccharides, glucose and galactose, before it can be absorbed. If not broken down, it remains in the small intestines and is passed along into the large intestine, a place it does not belong, with waste materials. The results can range from dehydration and diarrhea to intestinal cramps and bloating. The pain and bloating often experienced by the lactose intolerant after lactose ingestion are caused by intestinal bacteria that metabolize the lactose to which they are normally not exposed. Products of this fermentation include organic acids and various gases. Some products are available to allow lactose intolerant individuals to eat lactose containing products, and are meant to be ingested just before eating milk or dairy products.
Which of the following is a reasonable explanation of the observation that lactose intolerant individuals become dehydrated after lactose consumption?