Postgastrectomy malabsorption frequently follows gastric surgery. The small size of the gastric remnant causes inadequate mixing of food with digestive juices, particularly after a gastroenterostomy. With the loss of the pylorus, there may be rapid gastric emptying, poor mixing of bile and pancreatic secretions, and rapid transit down the small intestine. Incoordinated secretion and poor mixing of bile and pancreatic juice leads to fat maldigestion. Bacterial contamination in a blind loop (with gastroenterostomy) results in maldigestion of fat, carbohydrate, protein, vitamins and minerals. Gastric surgery that allows food to enter into the upper small intestine without dilution and with minimal digestion may "unmask" mild and subclinical celiac disease, lactase deficiency or pancreatic insufficiency.