Increased Vitamin B12 Requirement Associated with Chronic Acid Suppression Therapy

BACKGROUND: Assimilation of vitamin B12 from dietary sources requires gastric acid. By decreasing acid production, the proton pump inhibitors (PPIs) and histamine2 (H2)-blockers may reduce vitamin B12 absorption. OBJECTIVE: To determine whether chronic acid suppression therapy is associated with the initiation of vitamin B12 supplementation, we conducted a retrospective case–control study using a state-wide Medicaid population. METHODS: Case patients were identified as those who initiated vitamin B12 supplementation during the study period. Four control patients were age-and gender-matched to each case. Patients (n = 109 844) with a paid claim between September 27, 1995, and September 27, 1997, were eligible for inclusion. Chronic acid suppression therapy was defined as treatment with H2-blockers or PPIs for ≥10 of the 12 months prior to the first vitamin B12 injection. Comparisons were made between the case and control groups regarding exposure to chronic acid suppression therapy. RESULTS: One hundred twenty-five cases were matched to 500 controls. Twenty-three patients (18.4%) had been exposed to chronic acid suppression therapy compared with 55 (11.0%) of the control group (p = 0.025; OR 1.82; 95% CI 1.08 to 3.09). CONCLUSIONS: Initiation of vitamin B12 supplementation was associated with chronic gastric acid suppression therapy.