Atrophic gastritis is an inflammation of the lining of the stomach associated with a loss of glands present in the epithelium, the outermost layer of the stomach wall. It falls into the category of chronic gastritis, and is usually irreversible. Symptoms include stomach pain, nausea, vomiting, decreased appetite, and digestion problems. The most common cause of atrophic gastritis is pernicious anemia (or Biermer's anemia), due to an attack of the gastric mucosa by autoantibodies. The Helicobacter pylori bacterium is also involved in many chronic stomach problems, and can sometimes be responsible for atrophic gastritis. Atrophy of the glands decreases the capacity of incorporating various nutrients through the wall of the stomach.