Vitamin B12 deficiency may have a large variety of causes. In the intricate B12 absorption process a lot can go wrong. All causes listed below can lead to low B12 blood levels and have been described in specialist literature:
Gastric malabsorption
- pernicious anaemia
- (partial or total) gastrectomie, Gastric Bypass, Sleeve etc.
- Zollinger-Ellison syndrome
Intestinal malabsorption
- Ileocecal resection or disease, e.g. Crohn inflammatory bowel disease and tuberculosis ileitis
- Coeliac disease
- Blind loop syndrome
- luminal diseases: chronic pancreatitis and gastrinoma
- parasites: Giardia, bacterial overgrowth and fish tapeworm
Pancreatic Insufficiency
Reduced intake
- malnourishment
- strictly vegan or vegetarian diet
Congenital or hereditary factors
- intrinsic factor receptor deficiency
- Imerslund-Gräsback syndrome
- congenital intrinsic factor deficiency: ‘juvenile’ pernicious anaemia
- Cobalamin mutation (C-G-1-gen)
- transcobalamine 2 deficiency
Increased consumption
- hemolysis
- HIV
- Waldenström’s disease
- Kahler’s disease
Drugs and medication
- alcohol
- laughing gas
- proton pump inhibitors (antacids)
- H2 receptor antagonists
- metformin
- colchicine
- Slow K (potassium chloride) preparations
- cholestyramine
- birth control pill
- Levodopa
- Nitrofurantoine: Be careful with neurological conditions. These antibiotics are frequently prescribed for cystitis and affect vitamin B-intake. See: https://www.farmacotherapeutischkompas.nl/…/nitrofurantoine…
Sources: (a.o.) Hunt, A., Harrington, D., & Robinson, S. (2014). Vitamin B12 deficiency, Clinical review. 349. doi:10.1136/bmj.g5226
© 2014-2019 B12 Institute Nederland, Rotterdam, NL