Reading the diary
The diary links symptoms to specific foods. Bloating, gas, cramps, and loose stool appeared within 2 hours after fresh milk, ice cream, and tea with fresh milk. No symptoms followed plain yogurt or aged hard cheese. The foods that caused symptoms are all high in lactose; the tolerated foods are dairy products that are low in lactose. The pattern points to lactose as the trigger, not dairy as a whole.
The mechanism of lactose intolerance
Lactose, the sugar in milk, is digested by the brush-border enzyme lactase in the small intestine. When lactase activity is low, undigested lactose reaches the colon, where it draws water into the bowel by osmosis and is fermented by bacteria, producing gas and short-chain fatty acids. The result is bloating, flatulence, cramps, and loose stools within a few hours of a high-lactose food. Yogurt is tolerated because its live bacteria partly digest the lactose, and aged hard cheese loses most of its lactose during fermentation and ripening.
| Food | Lactose content | Her response |
|---|
| Fresh milk | High | Bloating, loose stool |
| Ice cream | High | Bloating, gas, loose stool |
| Tea with fresh milk | High | Cramps, loose stool |
| Plain yogurt | Low | No symptoms |
| Aged hard cheese | Very low | No symptoms |
Why the other conclusions are not supported
Stopping all dairy is not supported because she tolerated yogurt and cheese, and removing dairy completely would put her calcium intake at risk. A cow's milk protein allergy is unlikely because yogurt and cheese contain the same milk proteins yet caused no reaction. Dairy fat cannot explain the pattern either: aged hard cheese is high in fat and was tolerated. Watch out! Diary questions are solved by finding what the symptom-producing foods share that the tolerated foods lack.
Exam takeaway
In lactose intolerance, clients reduce lactose to the amount they tolerate rather than eliminating dairy. Options include lactose-free milk, yogurt, aged cheese, taking small portions of milk with meals, and lactase supplements, while keeping calcium and vitamin D intake from tolerated sources. Key point! Symptoms after milk and ice cream but not after yogurt or aged cheese indicate lactose intolerance.