The Ileum is the Major Site of Absorption of Vitamin B12 Analogues

Spencer Shaw, Elizabeth Jayatilleke, Samuel Meyers, Neville Colman, Barry Herzlich, Victor Herbert

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Non‐cobalamin vitamin B12 analogues constitute a significant percentage of total corrinoids in human serum. The source and means of absorption of analogues and their significance are largely unknown. We studied the sites of production and absorption of IV analogues by measuring serum vitamin B12 and analogues in 93 patients with various gastrointestinal diseases: pernicious anemia (PA), ileal resections, ileitis, Crohn's colitis, ulcerative colitis, and irritable bowel syndrome (IBS). Patients with PA had normal analogue levels that were unchanged or that rose during cessation of B12, administration. Patients with IBS, Crohn's colitis, ulcerative colitis, and total colectomies had B12 analogues in the normal range. Patients with diseased or resected ileums had low B12 and analogues. These data suggest that serum B12 analogues are absorbed in the ileum by a mechanism independent of intrinsic factor, and that colonic bacteria and endogenous metabolism of vitamin B12 do not contribute significantly to their level.

Original languageEnglish
Pages (from-to)22-26
Number of pages5
JournalAmerican Journal of Gastroenterology
Issue number1
StatePublished - Jan 1989


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