Vitamin B12 (cobalamin) is a unique vitamin that is not found in plant foods in an absorbable form. Its deficiency develops slowly (over years), but the consequences can be irreversible: damage to the nervous system and megaloblastic anemia. Find out who is at risk and how to determine the deficiency.
Why do you need vitamin B12
- Synthesis of myelin – the protective sheath of nerve fibers
- Hematopoiesis — maturation of erythrocytes in the bone marrow
- DNA synthesis — together with folic acid
- Methylation is a key process in the work of genes and detoxification
- Synthesis of neurotransmitters – serotonin, dopamine
Symptoms of B12 deficiency
B12 deficiency is disguised as various diseases:
Neurological:
- Numbness and tingling in hands and feet
- Violation of balance and coordination
- Muscle weakness
- Deterioration of memory, dementia
- Depression and psychosis (rare)
Hematological:
- Megaloblastic anemia – large, immature red blood cells
- Pale or slightly jaundiced skin
- Shortness of breath and palpitation on exertion
General:
- Chronic fatigue
- Inflammation and “burning” tongue (glossitis)
- Aphthous ulcers in the mouth
Who is at risk
- Vegans and vegetarians — B12 is found only in products of animal origin
- People over 50 — the production of intrinsic factor decreases (necessary for the absorption of B12)
- Patients on metformin — the drug reduces the absorption of B12 in the intestine
- Taking a PPI (omeprazole) — stomach acidity decreases, absorption worsens
- Diseases of the stomach and intestines — atrophic gastritis, Crohn’s disease
- After operations on the stomach — resection, bariatric surgery
B12 analysis: what to look for
Serum B12 is a first step, but not accurate enough. It is optimal to check:
- Serum B12: the norm is 200–900 pg/ml; the risk of deficiency is below 300 pg/ml
- Homocysteine: increases with B12 and folate deficiency. The norm is up to 15 μmol/l
- Methylmalonic acid (MMA): the most sensitive marker of cellular B12 deficiency
Forms of vitamin B12
- Methylcobalamin is an active form that does not require conversion; better for the nervous system
- Adenosylcobalamin is an active form for mitochondria and energy
- Hydroxycobalamin is a natural form from food, well absorbed
- Cyanocobalamin is a synthetic, cheap form; needs conversion; not recommended
Dosage and reception
- Prophylaxis for vegetarians: 250-500 mcg/day methylcobalamin
- Deficiency correction: 1000 mcg/day for 3 months
- After 50 years: 500–1000 mcg/day (impaired absorption through the gastrointestinal tract)
For severe deficiency or malabsorption, the doctor may prescribe B12 injections — they bypass the gastrointestinal tract.
Conclusion
B12 deficiency is a hidden threat for millions of people. If you’re vegan, taking metformin or PPIs, or over 50, get your B12 and homocysteine levels checked. Early correction prevents irreversible neurological damage.
