Drug-Induced Vitamin B12 Deficiency: Current Evidence, Diagnostic Challenges, and Therapeutic Strategies

Background/Objectives: Drug-associated vitamin B12 deficiency has emerged as a significant concern in clinical nutrition, as long-term use of metformin and proton pump inhibitors (PPIs) is common and may compromise cobalamin status through different physiological mechanisms. This narrative review summarizes mechanisms, risk profiles, diagnostic pitfalls, monitoring strategies and treatment options for vitamin B12 deficiency associated with chronic medication use.

Methods

A narrative literature review was conducted by searching major biomedical databases and screening reference lists to identify relevant clinical studies, meta-analyses, narrative and systematic reviews, and clinical practice guidelines on vitamin B12 physiology, drug–nutrient interactions, biomarkers of cobalamin status, and supplementation strategies.