Quick answer
Vitamin B12 deficiency causes tiredness, tingling in hands and feet, memory problems and anaemia. It is diagnosed with a blood test — below 200 pg/mL is deficient and 300–900 pg/mL is normal. Vegetarians and people on metformin are at higher risk.
Signs of B12 deficiency
- Fatigue and weakness
- Tingling, numbness or burning feet
- Memory problems and low mood
- Sore tongue or mouth ulcers
- Pale skin and breathlessness
Who is at risk?
- Vegetarians and vegans (B12 comes mainly from animal foods)
- Adults above 50
- People taking metformin or acid-reducing medicines long-term
- People with stomach or intestinal surgery or disease
B12 levels explained
| B12 level | Status |
|---|---|
| Below 200 pg/mL | Deficient |
| 200–300 pg/mL | Borderline |
| 300–900 pg/mL | Normal |
Frequently asked questions
Is fasting needed for a B12 test?
Fasting for 6–8 hours is preferred.
Can B12 deficiency be reversed?
Yes. With tablets or injections prescribed by a doctor, levels usually improve within weeks to months.
Medical disclaimer: This information is for general awareness only and is not a substitute for professional medical advice. Please consult a qualified doctor to interpret your results and before starting or changing any treatment.