Ambulatory care increased vitamin B12 requirement associated with chronic acid suppression therapy.

Background: Assimilation of vitamin B(12) from dietary sources requires gastric acid. By decreasing acid production, the proton pump inhibitors (PPIs) and histamine(2) (H(2))-blockers may reduce vitamin B(12) absorption.

Objective: To determine whether chronic acid suppression therapy is associated with the initiation of vitamin B(12) supplementation, we conducted a retrospective case-control study using a state-wide Medicaid population.