Vitamin B12 Deficiency and Its Neurological Effects

Impact of vitamin B12 insufficiency on haematopoiesis and the nervous system.

Written by: Saygı Hospital Health Guide Editorial Board

Last updated: June 11, 2026

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Dahiliye (İç Hastalıkları) department. Book Appointment →

What is Vitamin B12 Deficiency and Its Neurological Effects?

Vitamin B12 (cobalamin) deficiency disrupts DNA synthesis, leading to megaloblastic anaemia and damage to the myelin sheath of the nervous system. The most common causes are pernicious anaemia (autoimmune gastritis), malabsorption and inadequate intake.

Neurological involvement, termed subacute combined degeneration, affects the dorsal columns (loss of proprioception, ataxia) and lateral corticospinal tracts (spasticity, weakness). Peripheral neuropathy and cognitive impairment are also frequent.

Without early treatment, neurological damage may become permanent. Importantly, folate supplementation can mask the anaemia of B12 deficiency but does not prevent neurological injury; therefore both vitamins must be evaluated together.

Symptoms

Fatigue, pallor and dyspnoea (anaemia signs)

Numbness and tingling in hands and feet

Balance impairment and gait difficulty

Memory loss and cognitive slowing

Burning and smooth tongue (glossitis)

Depression and irritability

Risk Factors

Pernicious anaemia (autoimmune gastritis)

Vegetarian/vegan diet

Gastric bypass surgery

Chronic atrophic gastritis

Metformin use

Advanced age

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

Numbness in hands or feet, or balance disturbance
Memory loss or concentration difficulty
Macrocytic anaemia detected on full blood count
Routine monitoring after vegan diet or gastric surgery

Treatment Methods

Intramuscular cyanocobalamin injections (initially daily, then monthly)

High-dose oral B12 (1,000-2,000 µg/day in mild deficiency)

Lifelong therapy in pernicious anaemia

Early and aggressive treatment when neurological signs are present

Folate supplementation only after excluding B12 deficiency

Which Department to Visit?

You can visit our Dahiliye (İç Hastalıkları) department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

Learn About Dahiliye (İç Hastalıkları) Department

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.