Omeprazole interaction with vitamin absorption
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Omeprazole and Vitamin B12 Absorption
Omeprazole, a proton pump inhibitor, reduces stomach acid, which is necessary for releasing vitamin B12 from food proteins. This reduction in acidity leads to decreased absorption of protein-bound vitamin B12, as shown in both short-term and long-term studies 245. The risk of vitamin B12 deficiency is especially relevant for elderly patients or those with poor dietary intake. However, some studies suggest that adding acidic drinks, like juice, can improve B12 absorption in people taking omeprazole 25. While a drop in B12 absorption is clear, not all studies agree on whether this leads to clinically significant deficiency within the first few years of therapy .
Omeprazole and Vitamin C (Ascorbic Acid) Absorption
Omeprazole-induced hypochlorhydria (low stomach acid) also lowers vitamin C levels in the stomach. This effect is seen both in fasting conditions and after eating nitrate-rich foods, with omeprazole further reducing gastric ascorbic acid concentrations 18. The decrease in vitamin C may have implications for gastric health, as vitamin C helps protect against the formation of potentially harmful compounds in the stomach .
Omeprazole and Calcium, Magnesium, and Vitamin D Absorption
Calcium and magnesium absorption can be impaired by omeprazole because these minerals also require an acidic environment for optimal uptake . Short-term use of high-dose omeprazole has been shown to affect bone turnover, likely by decreasing calcium absorption, especially in people who are already vitamin D deficient . This may contribute to the increased risk of bone fractures seen with long-term proton pump inhibitor use.
Omeprazole and Iron Absorption
Iron absorption is also dependent on stomach acidity. Omeprazole’s acid-suppressing effect may reduce iron absorption, although there is limited direct evidence from prospective trials . The clinical significance of this interaction, especially in high-risk groups, remains to be fully established.
Omeprazole and Vitamin K Absorption
Omeprazole can cause bacterial overgrowth in the small intestine due to reduced stomach acid. This overgrowth may increase the production of certain forms of vitamin K (menaquinones), which can partially compensate for dietary vitamin K deficiency, but not enough to fully restore normal vitamin K status .
Conclusion
Omeprazole can interfere with the absorption of several vitamins and minerals, particularly vitamin B12, vitamin C, calcium, magnesium, and possibly iron and vitamin K. The risk of deficiency is higher with long-term use and in vulnerable populations such as the elderly or those with poor dietary intake. Simple dietary adjustments, like consuming acidic drinks, may help mitigate some of these effects, but healthcare providers should monitor patients on chronic omeprazole therapy for potential nutrient deficiencies.
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