Vitamin B12 and Folate Deficiency

🧭 When to suspect (vitamin B12 and folate deficiency)

Vitamin B12 and folate are both needed for DNA synthesis and red-cell production, and B12 is additionally essential for myelin integrity.

• That is why deficiency can produce haematological problems (a macrocytic anaemia), neurological problems, or both.

• The two deficiencies frequently coexist, so folate and B12 are always checked and interpreted together.

Do not wait for anaemia. B12 deficiency can present with neurological symptoms and a completely normal blood count, so a normal FBC never excludes it.

Current guidance recommends offering a B12 test to anyone with at least one symptom or sign and at least one risk factor; use clinical judgement where there are symptoms but no obvious risk factor.

Symptoms or signs such as:

• Unexplained fatigue

• Paraesthesia

• Balance problems

• Glossitis

• Cognitive ‘brain fog’

• Visual disturbance

Raise suspicion particularly with:

• A vegan or restricted diet

• Autoimmune gastritis (the cause historically called pernicious anaemia)

• Previous gastric or bariatric surgery or terminal ileal resection

• Coeliac or other autoimmune disease

• Long-term metformin or proton pump inhibitors

• Recreational nitrous oxide use

• Pregnancy where anaemia is not responding to iron

Source: NICE NG239 · MHRA Drug Safety Update