Final answer:
Clients with pernicious anemia lack the ability to properly absorb vitamin B12, which is essential for the production of healthy red blood cells.
Step-by-step explanation:
Clients with pernicious anemia lack the ability to properly absorb vitamin B12. Pernicious anemia is a condition that leads to vitamin B12 malabsorption and is commonly associated with various gastrointestinal issues such as Crohn's disease, surgical removal of parts of the stomach or intestines, as well as intestinal parasites and AIDS. Without sufficient vitamin B12, the body cannot produce adequate numbers of healthy red blood cells, leading to anemia.
Those particularly at risk for vitamin B12 deficiency include teenagers, children, vegans, and vegetarians, due to dietary restrictions or choices. In addition to poor dietary intake, factors such as excessive alcohol consumption, certain medications, and diseases like celiac disease can further compromise vitamin absorption. It's also important to note that additional nutritional deficiencies, such as that of iron and folate, can also lead to anemia, though these are distinct from pernicious anemia.