BiomarkersVitamin B12

Vitamins

Vitamin B12

For nerves, energy and red blood cells

On your report it may say: Cobalamin, Serum B12

Vitamin B12 keeps nerves healthy and helps make red blood cells. It comes almost only from animal foods, so vegetarians and vegans are at high risk of running low, which is very common in India.

Updated 2026-10-26

Typical ranges · pg/mL

Deficient below 200
Borderline 200–300
In range 300–900
High 900+

pmol/L = pg/mL × 0.738

Borderline results are often checked further with homocysteine or methylmalonic acid.

Ranges vary by lab, age and sex. The range printed on your report applies.

If it's low

Your body may not have enough B12 for nerves and red blood cells. Untreated, nerve damage can become permanent.

Common causes

  • Vegetarian or vegan diet
  • Metformin or acid-reducing medicines
  • Age over 50 (less stomach acid)
  • Gut conditions or surgery
  • Pernicious anaemia (an autoimmune condition)

What you might notice

  • Tiredness and weakness
  • Tingling or numbness in hands and feet
  • Poor memory or low mood
  • Sore, smooth tongue
  • Pale skin

If it's high

High B12 usually reflects supplements or injections and is not harmful in itself. A high level with no supplements should be checked by a doctor.

Common causes

  • Supplements or injections
  • Liver conditions
  • Some blood disorders

What you might notice

  • Usually no symptoms

Testing

Who should test
Vegetarians and vegans, people over 50, anyone on metformin or acid blockers, and anyone with tingling, memory changes or anaemia.
How to prepare
No fasting needed. Stop B12 supplements for a few days first if your doctor asks.
When to retest
8–12 weeks after starting supplements.

What can help

Food sources

Dairy (milk, curd, paneer)EggsFish and meatFortified foods

See a doctor promptly if you have numbness, balance problems or memory changes, or a very low level.

Common questions

Is a 'normal' B12 always fine?

Not always. Levels between 200 and 300 can still mean deficiency in some people.

Can curd and milk give enough B12?

They help, but many vegetarians still need a supplement.

Explore further

Sources

  1. NIH Office of Dietary Supplements: Vitamin B12 fact sheet for health professionals

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For general education only, not medical advice. Ranges shown are typical for adults; the range printed on your lab report applies. Talk to a qualified doctor about your results.