Causes of Low Vitamin B12 Levels

Low vitamin B12 intake - Vegetarianism, chronic alcoholism and older people

Autoimmune - Pernicious anaemia and Sjögren's syndrome

Food-bound cobalamin malabsorption - Atrophic gastritis, chronic gastritis and Helicobacter pylori-associated gastritis

Surgery - Post-gastrectomy and ileal resection

Malabsorption - Small intestinal bacterial overgrowth, chronic pancreatic exocrine insufficiency, Crohn 's disease, coeliac disease and achlorhydria

Obstetric/gynaecological - Oral contraceptive, hormone replacement therapy and pregnancy

Genetic - Transcobalamin II deficiency

Drugs - Metformin, proton pump inhibitors and histamine H2-receptor antagonists



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