Which dietary deficiency is most commonly associated with pernicious anemia?

Pernicious anemia is specifically linked to a deficiency in vitamin B12. This condition occurs when the body is unable to properly absorb this essential vitamin due to a lack of intrinsic factor, a protein produced in the stomach that is necessary for vitamin B12 absorption. Without sufficient vitamin B12, the production of red blood cells is impaired, leading to the characteristic symptoms of pernicious anemia, such as fatigue, weakness, and neurological issues.

Vitamin B12 plays a crucial role in DNA synthesis and the maturation of red blood cells in the bone marrow. Hence, a deficiency not only affects the hematological system but also can lead to neurological complications due to its role in maintaining the health of nerve cells. This clear association between pernicious anemia and vitamin B12 deficiency confirms that the correct answer is linked directly to the underlying mechanism of the disease.