To examine the literature surrounding the effects of omeprazole on oral iron absorption and discuss the long-term use of omeprazole and its effect on vitamins C and B 12 , calcium, and magnesium absorption.
The PubMed and MEDLINE databases were searched for reports published in English between January 1968 and August 2012, using the terms absorption, ascorbic acid, proton pump inhibitor, omeprazole, magnesium, calcium, ferrous sulfate, iron, and drug interactions.
Study Selection and Data Extraction
Studies and reports published in English were selected for review. In some cases, reference citations from selected review articles were evaluated as well.
Several micronutrients require an acidic environment for optimal absorption. Iron, vitamin C, and vitamin B 12 absorption are dependent on the intestine's acidic environment. Several studies and case reports describe associations of omeprazole with altered calcium, magnesium, and vitamin B 12 absorption. To date, there have been no prospective trials evaluating the effect of proton pump inhibitors (PPIs) on iron absorption.
Existing data support the conclusion that the acid-suppressing effect of omeprazole can have important clinical implications for vitamin and mineral therapy. Clinicians should be cognizant of this issue in practice. Further studies exploring the relationship of PPIs and iron deficiency are warranted, especially in high-risk populations such as the elderly.