Pernicious Anemia (Rare Cause of Vitamin B12 Deficiency) Causes, Symptoms, Diagnosis, Treatment Cobalamin (vitamin B12) and Folate Deficiency Province of British Columbia Vitamin B 12 3000 mcg Injection, 100 mL Petco Vitamin B12 Deficiency Vitamin B12 deficiency happens when the body does not have enough vitamin B12. Vitamin B12 is important for making healthy red blood cells and keeping nerves Oral Treatment Pernicious Anaemia Society