Changes in plasma free fatty acid concentration following oral lactose tolerance tests as a test for lactose absorption in infants and children.

Abstract

Changes in blood glucose and plasma free fatty acid (FFA) following oral lactose tolerance tests (LTT) were measured in three groups of children. In three out of seventeen infants with secondary lactose intolerance, only a small increase (less than 25 mg/100 ml) in glucose was found, but a normal decline (more than 50% of fasting value) in FFA concentration occurred. Resumption of milk feeding proved that they were not intolerant to lactose. Six infants (37%) without lactose intolerance who were on a normal lactose-containing diet showed only small increases in glucose; five of them showed a normal decline in plasma FFA. Nine out of thirteen children with no symptoms following oral LTT failed to show an increase in blood glucose, while in only one there was a decline of less than 50% in FFA concentration. Our results suggest that measurement of plasma FFA following oral LTT may be a more reliable test for cleavage and absorption of lactose than LTT alone, but for the final evaluation of this test a study of larger groups is obviously needed.