Diminished supply | |
Vegan nutrition | |
Alcohol abuse | |
Parasitic infections (e.g. fish tapeworm) | |
Reduced food intake (older people) | |
Pregnancy (relative deficit) | |
Disruption of cobalamin processing in the stomach | |
Gastric bypass/post-gastrectomy | |
Chronic gastritis (e.g. induced by alcohol abuse, helicobacter pylori infection) | |
Autoimmune gastritis resulting from antibodies reacting with parietal cells (pernicious anaemia) | |
Proton pump inhibitors and H2-receptor antagonists (sustained release of cobalamin) | |
Metformin, cytostatics, methyldopa, aminoglycosides e.g. (medicinal side effect) | |
Intestinal resorption problems | |
Intestinal bypass/ileal resection | |
Pathogenic intestinal flora | |
Ulcerating colitis | |
Crohn’s disease | |
Zollinger-Ellison syndrome | |
Imerslund-Gräsbeck syndrome | |
Defective transport and intracellular metabolism | |
Congenital deficiency in transcobalamin II | |
Congenital deficiency in various intracellular enzymes |