Vitamin B12 and ulcerative colitis: Links and more NHS 111 Wales Health A Z : Anaemia, vitamin B12 and folate deficiency Pernicious Anemia Treatment Guidelines: Don't Wait! PA Relief B12 INJECTIONS The Nurse Clinic Vitamin B12 deficiency, sometimes called cobalamin deficiency, happens when your body is either not getting enough or not absorbing enough vitamin B12 from the foods you eat. Vitamin B12 is an important