Final answer:
B12 deficiency anemia can be caused by small bowel resections, decreased intrinsic factor, excessive alcohol consumption, vegetarian/vegan diets, and malabsorption syndromes like celiac disease. Conditions like pregnancy and certain medications can also contribute to deficiencies.
Step-by-step explanation:
The causes of B12 deficiency anemia include a range of factors such as small bowel resections, which may occur due to surgeries for Crohn's disease, weight loss procedures, or other medical conditions requiring removal of part of the intestines. These surgeries can affect the body's ability to absorb vitamin B12. Decreased intrinsic factor (IF), necessary for B12 absorption, is commonly seen in conditions like pernicious anemia and can lead to B12 deficiency. Excessive alcohol consumption can interfere with the absorption of various nutrients including B12. Lastly, a vegetarian or vegan diet often lacks sufficient B12, as it is typically found in animal products, which can lead to a deficiency if not properly supplemented. Additionally, individuals with celiac disease or other malabsorptive syndromes may struggle to absorb B12, contributing to deficiency.
Conditions such as pregnancy, certain medications, and diseases like celiac disease, can also result in nutritional deficiencies including those of B12 and folate. It is crucial to have adequate folic acid intake during the early stages of pregnancy to prevent neurological defects in the developing fetus.