Vitamin B12

Vitamin B-12 (cobalamin) plays an essential role in red blood cell formation, cell metabolism, nerve function and the production of DNA, the molecules inside cells that carry genetic information. 

Food sources of cobalamin include poultry, meat, fish and dairy products. It is also added to some foods, such as fortified breakfast cereals, and is available as an oral supplement. Vitamin B-12 injections or nasal spray might be prescribed to treat this vitamin deficiency.

Cobalamin deficiency is not common in the U.S. However, people who follow a vegetarian or vegan diet might be prone to deficiency because plant foods don’t contain this essential vitamin. Older adults and people with digestive tract conditions that affect absorption of nutrients also are susceptible to this vitamin deficiency.

If left untreated, it can lead to anemia, fatigue, muscle weakness, intestinal problems, nerve damage and mood disturbances.