Disturbances in Fat Digestion Induced by Acidic Jejunal pH Due to Gastric Hypersecretion in Man

Abstract

The disorders of fat digestion caused by low intrajejunal pH were studied prior to operation in a patient with a gastrin-producing islet cell tumor (proved by bioassay), gastric hypersecretion, steatorrhea, and normal histological appearance of the jejunum. Samples of small intestinal contents were analyzed for pH, digestive enzymes, lipolytic products, and bile acids after administration of test meals; in vitro pH manipulation was carried out to define the reversibility of the observed changes. Irreversible inactivation of pancreatic lipase attributable solely to an acidic intrajejunal pH produced by gastric hypersecretion was the major defect. Consequent failure to form dispersible lipolytic products resulted in a low concentration of lipid in the micellar phase. In addition, the concentration of bile acids was low in acidic samples because of extensive dilution by gastric secretion as well as precipitation of glycine dihydroxy conjugated bile acids. In vitro neutralization caused the precipitated bile acid to enter solution but did not increase micellar lipid. When neutral samples, in which lipolysis proceeded normally, were acidified in vitro, the lipolytic products passed from the aqueous to the oil phase and bile acid precipitation also occurred. However, since lipolysis was greatly reduced in all acidic samples, inactivation of pancreatic lipase appeared to be the initial and dominant digestive abnormality.