Intrinsic factor (IF) is the gastric protein that promotes the intestinal uptake of vitamin B12 . Gastric IF from animal sources is used in diagnostic tests and in vitamin pills. However, administration of animal IF to humans becomes disadvantageous because of possible pathogenic transmis-sion and contamination by other B12binders. We tested the use of recombinant plants for large-scale production of pathogen-free human recombinant IF. Human IF was successfully expressed in the recombinant plantArabidopsis thaliana
