HealthMap

Metformin and Vitamin B12 Absorption

• Yes, long-term use of the prescription drug metformin (commonly prescribed for type 2 diabetes and insulin resistance) is well-documented to impair the intestinal absorption of Vitamin B12.

Mechanisms of Action

• Calcium Dependence: Metformin-induced malabsorption of B12 is primarily mediated by interfering with the calcium-dependent membrane action in the terminal ileum, which is required for the absorption of the intrinsic factor-B12 complex.
• Reversibility: This negative effect on B12 status can typically be corrected or bypassed by supplemental oral calcium intake or by increasing dietary and supplemental B12 intake.

Clinical Recommendations

• Testing: Individuals taking metformin long-term should periodically have their serum Vitamin B12 levels monitored.
• Supplementation: If deficiency or borderline levels occur, appropriate B12 supplementation (often sublingual methylcobalamin) should be utilized, alongside ensuring adequate calcium nutritional status.