Low B12 shows in the blood and the nerves.
Vitamin B12 helps the body make red blood cells and keeps the nerves healthy. It comes almost only from animal foods: milk, curd, paneer, eggs, fish and meat. Low B12 is very common in India, especially in vegetarians. It is easy to test for and to treat, and it is best found early, before the nerves are harmed.
In plain words.
Common causes: a vegetarian or vegan diet with little milk or curd; long use of metformin for diabetes, or of acidity tablets; older age; and conditions that stop the gut absorbing B12, such as pernicious anaemia or past stomach surgery.
Low B12 makes red cells that are too large and too few, so you become anaemic, tired and breathless. It also thins the protective coating on the nerves: tingling or numbness in the feet and hands, unsteady walking, poor memory or low mood.
Treatment is B12 by injection or tablets, depending on the cause and how low it is. Tiredness often improves within weeks. Nerves recover more slowly, and may not recover fully if the damage has gone on for a long time. That is why it is worth testing early.
Where B12 works
B12 helps the bone marrow make red cells, and keeps the fatty coating on the nerves healthy so signals jump quickly along them.
Red cells come out too few and too large: anaemia and tiredness. The nerve coating thins, signals slow, and the hands and feet tingle or go numb.
Go to hospital now if
- Sudden weakness or numbness of the face, arm or leg, or slurred speech: call 112. This may be a stroke.
- Leg weakness getting worse over days, new trouble walking, or losing control of urine or stools: go to hospital now.
- Severe breathlessness, chest pain or fainting: go to hospital now. Severe anaemia can strain the heart.
- Sudden confusion, or seeing or hearing things that are not there: go to hospital now.
Call 112 or go to the nearest emergency department. Ambulance: 108 (102 in some states).
See a doctor within a week or two if
- You have tingling or numbness in the feet or hands
- You have taken metformin for years and never had B12 checked
- You are vegetarian and feel tired or breathless
- You are pregnant or planning a pregnancy and eat little milk, curd or eggs
- Your memory is getting worse
Tests that help.
Not everyone needs every test. He decides which ones are worth doing for you.
| Test | What it tells |
|---|---|
| Vitamin B12 level | The first test. A borderline result may need the next one. |
| Homocysteine or methylmalonic acid | These rise when the body is truly short of B12. They help when the B12 level is borderline. |
| Complete blood count (CBC) with MCV | Shows anaemia, and whether the red cells are large (a high MCV). |
| Folate | Often checked alongside; it can be low too. |
| Intrinsic factor antibodies | Look for pernicious anaemia, in which the gut cannot absorb B12 from food. |
Have it ready.
Tick them off as you gather them. The ticks stay on this phone only.
Online, or in person?
Do not treat anaemia with folic acid alone before B12 has been checked. Folic acid can improve the blood count while nerve damage from low B12 carries on unseen. And do not stop metformin or acidity tablets on your own: B12 can be checked and topped up while you keep taking them.
A video call can
- Decide who needs testing, and which tests
- Plan B12 treatment by tablets or injections, and for how long
- Look for the cause, so it does not come back
- Follow your blood counts and symptoms as they recover
Needs a visit in person
- Blood tests, at a laboratory or by home collection
- B12 injections, at a clinic or by a nurse at home
- Examination of the nerves, when walking or feeling is affected
- Any sign in the red box: that is an emergency
Talk it through with Dr. Arya.
Bring your reports and medicines to a video consultation. He goes through them with you, in plain words, and says clearly if you need to be seen in person.
Book a video consultationDr. Prabhat Arya · MBBS, MD (Internal Medicine) · Delhi Medical Council Reg. No. DMC-83759