Comparison of whole milk and skim milk with aqueous lactose solution in lactose tolerance testing

Abstract

To compare whole milk and skim milk with an aqueous lactose solution in lactose tolerance testing, equivalent amounts of lactose present in whole milk, skim milk, or water were given to 21 healthy adults. Eleven of the 21 subjects were lactose intolerant on the basis of both criteria, i.e., maximum rise in blood glucose of less than 20 mg/100 ml above the fasting blood glucose level after ingesting 50 g lactose in water and experiencing gastrointestinal symptoms. On the average, the intensity of symptoms in the lactose-intolerant individuals was highest with the aqueous lactose solution, lower with skim milk, and lowest with whole milk. In the lactose-tolerant subjects, the mean rise in blood glucose was highest with aqueous lactose solution (37.3 mg/100 ml), lower with skim milk (26.7 mg/100 ml), and lowest with whole milk (13.5 mg/100 ml). Each of these means is significantly different from the other two (P < 0.005). Symptoms were not produced in any of the 10 lactose-tolerant subjects after the aqueous lactose solution, whole milk, or skim milk. The results indicate that some of the milk constituents have an effect on the responses to dietary lactose, presumably by causing a delay in gastric emptying and by a decrease in intestinal motility.