A review by experts in the field of lactose digestion addressed the question, “How often does lactose malabsorption result in symptoms of intolerance that require treatment?” Upon a comprehensive review of physiology and the results of well-controlled blinded trials, these experts concluded that “the clinical significance of lactose malabsorption has been overestimated by both the lay public and physicians.” Consuming a cup of milk with a meal “usually does not cause perceptible symptoms.”
The authors explain that many adults experience a genetically controlled decline after weaning in the lactase enzyme that digests lactose. This causes incomplete digestion or lactose malabsorption. The experts from this review say symptoms are more likely to occur when the amount of lactose consumed exceeds the 12 grams found in a cup of milk, or when lactose is consumed without other food. When counseling patients experiencing symptoms of lactose intolerance, they advise them to limit the amount of milk they consume to 2 cups per day, and divide it between two separate meals. To meet the 2010 Dietary Guidelines recommendation of three servings, lactose-free products may need to be used. They say in most cases, this simple approach is all that is needed.
Levitt M, Wilt T, Shaukat A. Clinical implications of lactose malabsorption versus lactose intolerance. J Clin Gastroenterol. 2013;47(6):471-480.