What essential vitamin is deficient in pernicious anemia?

Pernicious anemia is a specific type of anemia that results from an inability to absorb vitamin B12 (cobalamin), which is essential for the production of red blood cells and the maintenance of a healthy nervous system. In pernicious anemia, there is often a lack of intrinsic factor, a protein produced by the stomach that is necessary for the absorption of vitamin B12 in the intestines. Without sufficient vitamin B12, red blood cells do not mature properly, leading to a reduced number of healthy red blood cells and resulting in symptoms such as fatigue, weakness, and neurological issues.

Vitamin A, C, and D play various roles in the body, such as maintaining vision, supporting the immune system, and regulating calcium levels, respectively. However, they do not have a direct link to the specific condition of pernicious anemia, which distinctly revolves around a deficiency in vitamin B12. Therefore, understanding the essential role of vitamin B12 in cellular health and its absorption process clarifies why it is the critical vitamin associated with pernicious anemia.