Background: The intestines are the major site of zinc absorption and excretion. Reduced gastric acid secretion and elevated gastric pH is an important factor affecting intestinal mineral absorption.
Methods: Gastric pH and volume, and basal and maximal acid outputs were measured in 14 healthy volunteers. Plasma zinc levels were then measured at baseline and 1, 2, 3 and 4 hours after oral administration of 300 mg zinc sulfate. The experiment was repeated after omeprazole administration (60 mg/day orally) for 7 days.
Results: Omeprazole administration significantly increased fasting gastric pH (5.5 versus 2.4; p < 0.001). Mean basal gastric acid output (1.6 vs 8.0 mEq/h; p < 0.001) and maximal acid output (20.6 vs 106.6 mEq/h; p < 0.001) decreased after omeprazole administration. Zinc absorption decreased after omeprazole administration (141  mg/dL/h) compared with pre-omeprazole values (245 ; p < 0.01).
Conclusion: Suppression of gastric acid secretion by omeprazole reduces intestinal absorption of zinc.