The Critical Role of Vitamin B12
Vitamin B12, or cobalamin, is an essential nutrient vital for nerve and blood cell health and DNA synthesis. Deficiency can cause serious issues, including anemia, fatigue, neuropathy, and cognitive problems. While diet is a source of B12, certain medications disrupt absorption.
How Medications Interfere with Vitamin B12 Absorption
Drug-nutrient interactions are a significant concern. Many medications lower B12 levels by reducing the stomach acid needed to release B12 from food or by interfering with absorption in the small intestine. Long-term use increases deficiency risk.
Gastric Acid Inhibitors: PPIs and H2 Blockers
These drugs treat heartburn and ulcers.
- Proton Pump Inhibitors (PPIs): Drugs like omeprazole (Prilosec) and lansoprazole (Prevacid) suppress gastric acid. Long-term use (two or more years) is linked to increased B12 deficiency risk, especially at higher doses.
- H2 Blockers: Including famotidine (Pepcid AC), these also reduce stomach acid, hindering B12 absorption from food. Long-term use is associated with elevated deficiency risk.
Metformin: A Common Diabetes Medication
Metformin, used for type 2 diabetes, commonly reduces B12 levels. Risk increases with dose and duration. It's thought to interfere with B12 absorption in the ileum. Long-term use is linked to deficiency, anemia, and neuropathy.
Other Medications of Concern
Other drugs impacting B12 include:
- Colchicine: For gout, this can cause B12 malabsorption by affecting the ileal mucosa.
- Chloramphenicol: This antibiotic can interfere with B12's therapeutic effects, potentially impairing bone marrow function.
- Antiseizure Medicines: Older drugs like phenytoin (Dilantin) may lower B12 absorption.
- Aminosalicylic Acid (Paser): Used for digestive issues, it can lower B12 absorption.
- Vitamin C: Some sources suggest taking vitamin C at the same time as vitamin B12 might reduce the available B12. It is often recommended to take them at least two hours apart.
| Medication Class/Name | Brand Names (Examples) | Mechanism of Interaction | Risk Factors |
|---|---|---|---|
| Proton Pump Inhibitors (PPIs) | Prilosec, Nexium, Prevacid | Reduces stomach acid | Long-term use (>2 years), higher doses |
| H2 Blockers | Pepcid AC, Tagamet HB | Reduces stomach acid | Long-term use (>1 year) |
| Metformin | Glucophage, Fortamet | Impairs absorption in the ileum | High dose, long duration of use |
| Colchicine | Colcrys, Mitigare | Alters ileal mucosa function | Long-term therapy |
| Chloramphenicol | N/A | Interferes with bone marrow response to B12 | Concurrent use for anemia treatment |
Managing Interactions and Preventing Deficiency
Taking these medications long-term doesn't always require stopping them, but management is key.
- Monitoring: Periodic B12 level monitoring is advised for patients with risk factors, especially those on long-term metformin or acid inhibitors. Symptoms like fatigue, a sore tongue, or neuropathy warrant medical discussion.
- Supplementation: Deficiency can be corrected with B12 supplements, which don't require stomach acid for absorption and are effective even with PPIs or H2 blockers. Options include oral, sublingual, or injectable forms.
- Consult a Healthcare Professional: Always discuss medications and supplements with your doctor or pharmacist. They can assess your risk, recommend monitoring, and guide management to prevent nutrient depletion.
Conclusion
While treating various conditions, common medications can deplete vitamin B12. PPIs, H2 blockers, metformin, colchicine, and others can interfere with absorption. Recognizing deficiency signs and discussing monitoring and management with a healthcare provider can mitigate this risk, maintaining both treatment goals and nutritional health.
For more information from a trusted source, you can visit the NIH Office of Dietary Supplements Vitamin B12 Fact Sheet for Consumers.
