This article in the Drug and Therapeutics Bulletin (DTB) reviews the issues around adopting an oral vitamin B12 replacement regimen more widely in the UK. It discusses the following topics:

• Vitamin B12 deficiency

• Diagnosing deficiency

• Ways of replacing vitamin B12

• Doses recommended in UK

• How effective is high-dose oral replacement?

• Comparison with intramuscular therapy

• Cautions with vitamin B12

• Costs

The conclusion of the bulletin is that most patients without a dietary deficiency should also respond well to daily doses of 1 mg oral cyanocobalamin, though this is an unlicensed indication in the UK. The authors recognised that some patients may still require parenteral vitamin B12 if they have malabsorption across the entire gastrointestinal tract or poor adherence to oral therapy. They call for a licensed 1 mg vitamin B12 tablet to become available in the UK and for further studies to determine whether high-dose oral therapy is suitable for patients with vitamin B12 deficiency and severe neurological defects.