Inflammatory Bowel diseases Journal, 2014 20, 1120-1128
Vitamin B12 is absorbed from the terminal ileum, which is the end portion of the small bowel. One third to half of patients with Crohn’s disease have disease affecting the ileum. It has therefore been traditionally believed, that patients with severe Crohn’s disease affecting the ileum or those patients who have had surgical removal of the terminal ileum are at a risk of vitamin B12 deficiency. Vitamin B12 deficiency can cause a type of anaemia (low haemoglobin) called megaloblastic anaemia and other symptoms due to abnormalities of the nervous system. In this paper, the authors did a systematic search of medical literature to assess if IBD predisposes to a deficiency of vitamin B12. Forty-two relevant research publications were identified. Through a systematic evaluation of these publications, the authors of this paper concluded that Crohn’s disease regardless of involvement of the ileum is not associated with higher risk of vitamin B12 deficiency. However, when patients have more than 20 cm of the ileum surgically removed, there is a risk of deficiency and warrants treatment with vitamin B12 supplementation. The authors also concluded that when a deficiency is suspected the diagnosis is properly confirmed because life long treatment with vitamin B12 (commonly as an intramuscular injection) may be necessary.
I think this paper is hugely beneficial to gastroenterologists to identify patients who are at risk of developing vitamin B12 deficiency and treat accordingly to avoid long term ill effects due to the deficiency. It will also help clinicians to avoid unnecessary treatments with B12 injections in patients who are at a low risk of developing deficiency.