Can vitamin B12 deficiency cause anaemia?

Vitamin B12 helps the bone marrow make red blood cells that carry oxygen. When the body does not have enough B12, cells may develop abnormally and fail to work efficiently. This can produce anaemia, with tiredness, weakness, breathlessness on exertion, dizziness or a pale appearance. The deficiency may relate to diet, reduced absorption, stomach or bowel conditions, or some medicines. Symptoms can overlap with other causes of anaemia, so a symptom alone cannot identify the cause.

Arrange a medical assessment if tiredness or other symptoms persist. A clinician may review your diet, medicines and health history and request blood tests, including a blood count and vitamin levels. Treatment depends on why B12 is low and may involve prescribed supplements by mouth or injection. Do not rely on iron treatment alone unless testing shows iron deficiency; different forms of anaemia need different treatment.

Seek prompt medical help for chest discomfort, severe breathlessness, fainting, confusion, marked weakness or a fast heartbeat with feeling unwell. Numbness, balance changes or new difficulty walking also deserve timely assessment because B12 deficiency can affect nerves as well as blood cells.

Ask which blood tests are needed, what may be causing the deficiency, whether your medicines or diet affect absorption, and how treatment will be monitored. Ask when symptoms should begin to improve and whether nerve symptoms need separate assessment.