Vitamin B12 deficiency anemia is a blood problem that occurs when there is not enough of this vitamin in the body. Vitamin B12 helps your body make red blood cells, which carry oxygen. Without enough vitamin B12, the body does not have enough red blood cells (anemia). Anemia may make you feel weak and tired.

Vitamin B12 (also called cobalamin) is found in animal products such as meat, eggs, and milk products. Vitamin B12 deficiency anemia usually occurs when the body can't absorb this vitamin from food. It can also occur if a person's diet doesn't include enough of this vitamin.

If this type of anemia is suspected, the doctor will order blood tests that can help diagnose this condition.

Vitamin B12 deficiency anemia is treated with vitamin B12 supplements. These may be given as shots or pills. Most people need to take supplements for the rest of their lives to keep the condition from coming back.