What is pernicious anemia?

B12 deficiency. It is an autoimmune disease in which your body develops antibodies against intrinsic factor and gastric parietal cells which are needed to absorb b12, a vital nutrient. These patients will need to get im injections of b 12 lifeterm since they cannot absorb B12 naturally from their diet.
Low B12. Secondary to absorb it, or secondary to not eating it with your food. True vegans will develop it from inadequate intake. Must take supplemental B12!