THE RECENTLY described syndrome of intestinal lactase deficiency associated with milk intolerance in an adult1-4 has renewed interest in lactose absorption. This study was undertaken because no detailed data on the oral lactose tolerance test in the normal adult were available. The majority of normal individuals in the present study experienced diarrhea associated with little or no rise in their blood sugar levels after receiving an oral lactose load.
The 25 subjects tested (Table) were either adult hospital patients ready for discharge or young male physicians. None of the subjects had gastrointestinal or hepatic disease, diabetes, hypoglycemia, milk intolerance, or diarrhea. Twenty-one of the subjects received 100 gm of lactose dissolved in 500 ml of water. Four other subjects received 50 gm lactose in 500 ml of water. Following an overnight fast, blood specimens were obtained in the fasting state and at intervals during two hours after