Final answer:
Pernicious anemia is primarily caused by the poor absorption of vitamin B12 and can be related to digestive system surgeries, certain diseases, or diets lacking in animal products. Iron deficiency anemia, the most common type, is due to insufficient iron intake or absorption.
Step-by-step explanation:
Pernicious Anemia Overview
Pernicious anemia typically occurs due to poor absorption of vitamin B12, which can be exacerbated by conditions like Crohn's disease, surgical removal of the stomach or intestines, intestinal parasites, and AIDS. This type of anemia is also prevalent among particular dietary choices such as those followed by vegans and vegetarians, who may not consume adequate amounts of B12 since it is primarily found in animal products.
Furthermore, conditions such as pregnancy, excessive alcohol consumption, medications, and diseases like celiac disease can lead to nutrient deficiencies including folate and vitamin B12, contributing to the onset of anemia. It's crucial, especially during pregnancy, to maintain appropriate levels of folate to prevent neurological defects in the developing fetus.
Iron deficiency anemia is the most common form, occurring when iron intake or absorption is inadequate, affecting teens, children, and those following a plant-based diet. Without enough iron, the body cannot produce enough functional hemoglobin. Anemias such as megaloblastic and aplastic can arise from inadequate dietary intake or inability to properly utilize B12 and folate, or from insufficient red blood cell stem cells, respectively. Moreover, external factors like lead exposure can also damage the bone marrow and cause anemia.