Vitamin B12
Body function
Nerve function; red blood cell production; DNA synthesis; energy metabolism
Daily requirement
2.4 mcg/day; absorption declines with age and with metformin/PPIs
Deficiency signs
Fatigue, nerve tingling, poor memory, low mood, mouth ulcers, pale skin
Excess risks
Very low toxicity; excess excreted. Rare: acne-like rash at very high doses
At-risk groups
Vegans, vegetarians, over-50s, people on metformin or PPIs, those with pernicious anaemia
Supplement forms
Methylcobalamin or cyanocobalamin; sublingual, injection (medical), oral tablet
Food sources
- Eggs (whole, boiled) — 2.6 mcg B12 per 2 eggs
Related symptoms
Educational information only — not medical advice. This content does not diagnose, treat, or replace consultation with a qualified healthcare professional. Always seek professional medical advice for symptoms, supplement use, or health concerns.