Pernicious Anemia is a form of megaloblastic anemia due to vitamin B-12 deficiency. More basically, your body doesn't make enough red blood cells which causes B-12 deficiency. Vitamin B-12 cannot be produced by the human body, and must therefore be obtained from diet. The anemia is created by your body's inability to produce DNA in sufficient quantities for blood cell synthesis.

When you have an anemia, the blood cannot carry enough oxygen to the cells of the body, causing you to feel tired, but also causing permanent damage to your body. Symptoms include heart problems, problem with your nerves, digestive tract infections and much more.

Anything in the stomach that affects the normal acidity and digestive processes, ranging from infections to acid reflux medicine to aging, may also interfere with B12 absorption.

Lots of times, this condition is cured by taking vitamin B-12 supplements, but you consult a doctor before doing so.