OMEPRAZOLE THERAPY CAUSES MALABSORPTION OF CYANOCOBALAMIN (VITAMIN-B12)

Objective: To evaluate protein-bound cyanocobalamin (vitamin B-12) absorption before and after omeprazole (Prilosec) therapy in healthy male volunteers. Design: Clinical trial in which each volunteer served as his own control. Setting: Outpatient department of a university medical center. Participants: Ten healthy, male volunteers 22 to 50 years old. Intervention: Each participant had a modified Schilling test (protein-bound cyanocobalamin) and a gastric analysis, as well as measurements of serum vitamin B-12, gastrin, and folate levels. Five patients were then randomly assigned to take either 20 mg or 40 mg of omeprazole daily. After 2 weeks of omeprazole therapy, these tests were repeated. Measurements: The modified Schilling test, gastric analysis, serum gastrin level, folate level, and cyanocobalamin level. Results: At the end of the 2-week treatment period, cyanocobalamin absorption decreased from 3.2% to 0.9% (P = 0.031) in participants receiving 20 mg of omeprazole daily. In patients taking 40 mg of omeprazole daily, cyanocobalamin absorption decreased from 3.4% to 0.4% (P <. 0.05). Conclusions: Omeprazole therapy acutely decreased cyanocobalamin absorption in a dose-dependent manner.