The Intestine Plays a Substantial Role in Human Vitamin B6 Metabolism: A Caco-2 Cell Model

Research output: Contribution to journalArticle


Background: Vitamin B6 is present in various forms (vitamers) in the diet that need to be metabolized to pyridoxal phosphate (PLP), the active cofactor form of vitamin B6. In literature, the liver has been reported to be the major site for this conversion, whereas the exact role of the intestine remains to be elucidated. Objective: To gain insight into the role of the intestine in human vitamin B6 metabolism. Materials and Methods: Expression of the enzymes pyridoxal kinase (PK), pyridox(am)ine phosphate oxidase (PNPO) and PLP-phosphatase was determined in Caco-2 cells and in lysates of human intestine. Vitamin B6 uptake, conversion and excretion were studied in polarized Caco-2 cell monolayers. B6 vitamer concentrations (pyridoxine (PN), pyridoxal (PL), PLP, pyridoxamine (PM), pyridoxamine phosphate (PMP)) and pyridoxic acid (PA) were quantified by ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) using stable isotope-labeled internal standards. Results: The enzymatic system involved in vitamin B6 metabolism (PK, PNPO and PLP-phosphatase) is fully expressed in Caco-2 cells as well as in human intestine. We show uptake of PN, PM and PL by Caco-2 cells, conversion of PN and PM into PL and excretion of all three unphosphorylated B6 vitamers. Conclusion: We demonstrate, in a Caco-2 cell model, that the intestine plays a substantial role in human vitamin B6 metabolism.


  • Monique Albersen
  • Marjolein Bosma
  • Nine V.V.A.M. Knoers
  • Berna H.B. de Ruiter
  • Eugène F. Diekman
  • Jessica de Ruijter
  • Wouter F. Visser
  • Tom J. de Koning
  • Nanda M. Verhoeven-Duif
External organisations
  • University Medical Center Utrecht
  • University Medical Center Groningen
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Physiology
Original languageEnglish
Article numbere54113
JournalPLoS ONE
Issue number1
Publication statusPublished - 2013 Jan 14
Publication categoryResearch
Externally publishedYes