Pernicious anemia is a chronic autoimmune disease resulting from impaired absorption of vitamin B12 due to a lack of intrinsic factor (IF) in the stomach.

Anemia, also known as blood deficiency, arises from a reduced number of red blood cells in the body's blood content. Red blood cells, also known as erythrocytes, contain hemoglobin and are responsible for oxygen transport. When a person experiences anemia, there are serious problems in the transport of both oxygen and nutrients in the body.

Pernicious anemia is a type of anemia that causes blood deficiency, with the main cause being a deficiency of vitamin B12. While B and C vitamins are water-soluble, B12 has a different structure and is stored in fat. Therefore, restoring B12 levels in the body can take a long time, and the longer this takes, the greater the risk factor for pernicious anemia.

Vitamin B12 absorption is carried out by a protein stimulated by stomach cells; when this protein is insufficient, problems occur in B12 absorption, and pernicious anemia may develop. With impaired absorption of vitamin B12 in the intestines, stores can be depleted within 3-5 years, and symptoms of pernicious anemia may become apparent.