What type of anemia results from a deficiency in Vitamin B12?

Megaloblastic anemia is directly associated with a deficiency of Vitamin B12. This type of anemia is characterized by the production of unusually large and immature red blood cells, known as megaloblasts, due to the impaired DNA synthesis that occurs when Vitamin B12 is not available in sufficient amounts.

Vitamin B12 plays a crucial role in the formation of red blood cells and in the proper functioning of the nervous system. When deficient, the red blood cells cannot divide normally, leading to the production of larger cells that are not fully functional. This anemia can present with symptoms such as fatigue, weakness, and neurological issues due to the involvement of Vitamin B12 in the synthesis of myelin, the protective sheath around nerves.

The other types of anemia listed do not primarily stem from a Vitamin B12 deficiency. Normocytic anemia, for instance, is caused by several factors such as chronic disease or acute blood loss, while sideroblastic anemia is related to the body's inability to incorporate iron into hemoglobin. Iron deficiency anemia, as the name suggests, arises specifically from a lack of iron, affecting the synthesis of hemoglobin rather than the formation of red blood cells in the context of Vitamin B12 deficiency.