Review article: potential gastrointestinal effects of long-term acid suppression with proton pump inhibitors

This review examines the evidence for the development of adverse effects du e to prolonged gastric acid suppression with proton pump inhibitors. Potent ial areas of concern regarding long-term proton pump inhibitor use have inc luded: carcinoid formation; development of gastric adenocarcinoma (especial ly in patients with Helicobacter pylori infection); bacterial overgrowth; e nteric infections; and malabsorption of fat, minerals, and vitamins. Prolonged proton pump inhibitor use may lead to enterochromaffin-like cell hyperplasia, but has not been demonstrated to increase the risk of carcinoi d formation. Long-term proton pump inhibitor treatment has not been documen ted to hasten the development or the progression of atrophic gastritis to i ntestinal metaplasia and gastric cancer, although long-term studies are req uired to allow definitive conclusions. At present, we do not recommend that patients be tested routinely for H. pylori infection when using proton pum p inhibitors for prolonged periods. Gastric bacterial overgrowth does incre ase with acid suppression, but important clinical sequelae, such a higher r ate of gastric adenocarcinoma, have not been seen. The risk of enteric infe ction may increase with acid suppression, although this does not seem to be a common clinical problem with prolonged proton pump inhibitor use. The ab sorption of fats and minerals does not appear to be significantly impaired with chronic acid suppression. However, vitamin B-12 concentration may be d ecreased when gastric acid is markedly suppressed for prolonged periods (e. g. Zolllinger-Ellison syndrome), and vitamin B-12 levels should probably be assessed in patients taking high-dose proton pump inhibitors for many year s. Thus, current evidence suggests that prolonged gastric acid suppression wit h proton pump inhibitors rarely, if ever, produces adverse events. Neverthe less, continued follow-up of patients taking proton pump inhibitors for ext ended periods will provide greater experience regarding the potential gastr ointestinal adverse effects of long-term acid suppression.