Mucosal enzyme activities in the functioning intestine one and six months after jejuno-ileal by-pass operation for obesity.

Enzyme activity changes in the functioning segment (the shunt) of the small intestine during the first 6 months after by-pass operation for obesity were investigated. At the ligament of Treitz no significant changes in disaccharidase activities occurred, whereas two intracellular beta-galactosidases showed increased activities after 1 month. In the jejunal part of the shunt (studied in patients operated on with a long jejunal functioning segment) there was an in most cases temporary decrease in lactase activity after 1 month. Other enzymes studied showed less pronounced changes. In the ileal part of the shunt (studied in patients operated on with a long ileal functioning segment) the initially low enzyme activities increased especially after 6 months towards the levels normally seen in the jejunal mucosa. The lactase activity, however, remained low also after 6 months. Adaptive changes in the functioning small-intestinal segment is probably an important factor in weight stabilization and, in some cases, in the weight increase that recurs after the initial period of rapid weight loss after by-pass operation for obesity.