Final answer:
Pernicious anemia arises from a lack of dietary vitamin B12 or insufficient production of intrinsic factor by the stomach, necessary for vitamin B12 absorption. This can lead to serious health issues, including impaired red blood cell production and neurological problems.
Step-by-step explanation:
Pernicious anemia occurs when there is a dietary deficiency of vitamin B12 or when a person's stomach does not produce enough intrinsic factor. This form of anemia is distinct because it does not respond to increased iron in the diet. The body requires vitamin B12 for several critical functions, including the production of mature red blood cells and normal neurological functioning. The absorption of this vitamin in the intestines cannot occur without intrinsic factor, a substance secreted by the stomach. Individuals may be at risk for vitamin B12 deficiency due to conditions like Crohn's disease, surgical removal of parts of the stomach or intestines, intestinal parasites, AIDS, diets lacking in animal products such as in vegan or vegetarian diets, or excessive alcohol consumption.
Furthermore, not consuming sufficient amounts of folate, which can occur due to a diet with a lack of certain vegetables or overcooking them, can also lead to megaloblastic anemia, which is characterized by a deficiency in vitamin B12 and/or folate. It is important to note that during pregnancy, adequate folic acid intake is critical to reduce the risk of neurological defects. Sources of vitamin B12 include liver, eggs, meat, and fish, with a daily requirement of around 5 µg/day. Without proper intake or absorption of vitamin B12, in addition to neurological issues, megaloblastic or pernicious anemia can develop.