Vitamin B12

Vitamin B12 is important for the normal functioning of the brain and nervous system and in the formation of red blood cells. It also helps make DNA.

Vitamin B12 is absorbed primarily by the last part of the ileum, which is called the terminal ileum.

Crohn’s disease may inflame the terminal ileum, so it can’t absorb vitamin B12. And surgical treatment of Crohn’s disease sometimes may involve removing the terminal ileum.

In either case, the result can be low levels of vitamin B12. Low levels can be treated with injections of vitamin B12. The vitamin is also available in a nasal spray.

  • Normal value: over 250 picograms per milliliter (pg/mL)