Omeprazole and calcium absorption
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Omeprazole and Calcium Absorption: Effects and Mechanisms
Omeprazole, Gastric Acid Suppression, and Calcium Absorption
Omeprazole is a proton pump inhibitor (PPI) that reduces stomach acid production. Several studies show that this acid suppression can decrease calcium absorption. In both animal and human studies, omeprazole increased gastric pH and led to a reduction in apparent calcium absorption, especially when higher doses were used or when calcium was provided as calcium carbonate, which requires an acidic environment for optimal absorption 1257.
Short-Term Omeprazole Use and Calcium Homeostasis
Short-term use of omeprazole (30 days) in young adults and postmenopausal women has shown mixed results. Some studies found a borderline decrease in serum calcium and an increase in bone turnover markers, suggesting reduced calcium absorption, particularly in individuals with vitamin D deficiency . However, other research in healthy adults and postmenopausal women found no significant reduction in fractional calcium absorption after 30 days of omeprazole use, indicating that short-term hypochlorhydria may not always impair calcium absorption from food 48.
Calcium Source Matters: Calcium Carbonate vs. Other Forms
The form of calcium supplement is important. Calcium carbonate absorption is more dependent on stomach acid, and omeprazole significantly reduced its absorption in postmenopausal women. In contrast, calcium from sources like sour milk beverages or soluble fiber-enriched milk was less affected by omeprazole, possibly because these forms are less reliant on gastric acidity for absorption 17.
Special Populations: Dialysis Patients and Hypercalcemia
In dialysis patients, omeprazole reduced the post-meal increase in plasma calcium, supporting the idea that gastric acid is important for calcium absorption in this group as well. However, in clinical practice, omeprazole did not significantly reduce hypercalcemia in dialysis patients using calcium-based phosphate binders, suggesting limited benefit in this context 59.
Potential Solutions: Dietary Modifications
Adding dietary acids like lactic acid or consuming sour milk beverages increased calcium absorption in rats treated with omeprazole, even when gastric pH remained high. This suggests that certain dietary modifications may help counteract the reduced calcium absorption caused by PPIs .
Clinical Implications and Recommendations
The evidence suggests that omeprazole and other PPIs can reduce calcium absorption, especially from calcium carbonate supplements and in individuals with low vitamin D levels or those at risk for osteoporosis. However, the effect may be less pronounced with dietary calcium or other supplement forms. Clinicians should be aware of these interactions, especially in populations at risk for bone loss or those requiring long-term PPI therapy 2346.
Conclusion
Omeprazole can decrease calcium absorption by raising gastric pH, particularly affecting calcium carbonate supplements and certain at-risk populations. The impact is less clear with dietary calcium and over short-term use. Dietary strategies, such as using more soluble forms of calcium or adding dietary acids, may help mitigate this effect. Awareness of these interactions is important for managing bone health in patients on long-term omeprazole therapy.
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