Vitamin B12 Deficiency: Chemistry of Vitamin B12 and its Potential Effects

Alswaied, Khaulah Abdulaziz; Emam, Arwa Mohammad; Alhamed, Arwa Abdullah; Aljabaan, Turki Ali; Alzaher, Mohammed Abdullah; Alhizan, Khloud Awadh; Alqarni, Zainab Ali; Alharbi, Khlood Khaldan; Alshammari, Ebtesam Owaid; Al Dosari, Afnan Mohammed; Al Mutairi, Hala Halal; Alshikhi, Wasan Mohammed; Alanazi, Seham Ahmed; Al Enazi, Fahad Husayyan; Alotaibi, Suhoud Saud

doi:10.21608/ejchem.2025.396874.11949

Vitamin B12 Deficiency: Chemistry of Vitamin B12 and its Potential Effects

Document Type : Review Articles

Authors

Ministry of National Guard, Saudi Arabia

10.21608/ejchem.2025.396874.11949

Abstract

Background: Vitamin B12 (cobalamin) is an essential water-soluble vitamin crucial for DNA synthesis, fatty acid metabolism, and myelin sheath maintenance. Deficiency arises from dietary insufficiency, malabsorption (e.g., pernicious anemia, Crohn’s disease), or toxin exposure (e.g., nitrous oxide). Long-term deficiency leads to megaloblastic anemia and irreversible neurological damage, including subacute combined degeneration of the spinal cord (SCDSC).

Aim: This review examines the biochemistry, pathophysiology, clinical manifestations, and management of vitamin B12 deficiency, emphasizing diagnostic challenges and therapeutic strategies.

Methods: A comprehensive analysis of B12 absorption, metabolic roles, and deficiency etiologies was conducted. Diagnostic approaches (serum B12, methylmalonic acid [MMA], homocysteine levels) and treatment modalities (parenteral/oral supplementation) were evaluated.

Results: Deficiency manifests as macrocytic anemia (elevated MCV, hypersegmented neutrophils) and neurological symptoms (neuropathy, ataxia, cognitive decline). Elevated MMA and homocysteine confirm diagnosis, particularly in borderline serum B12 cases. Treatment involves intramuscular B12 (1000 mcg/month) or high-dose oral therapy (1000–2000 mcg/day) for malabsorption. Early intervention improves hematologic recovery, but neurological damage may persist if treatment is delayed.

Conclusion: Vitamin B12 deficiency requires prompt recognition and lifelong management in malabsorptive etiologies. Interprofessional collaboration (clinicians, dietitians, pharmacists) optimizes outcomes, particularly in high-risk groups (vegans, post-gastrectomy patients, elderly). Proactive screening and patient education are critical to preventing irreversible complications.

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