VITAMIN B12 deficiency is estimated to affect 10% to 15% of the people older than 60 years.1 The most common causes of cobalamin (vitamin B12) deficiency are pernicious anemia and food-cobalamin malabsorption. These are distinct entities that can be readily distinguished by a Schilling test. Pernicious anemia and food-cobalamin malabsorption also share several similarities, namely, an increasing prevalence with age, an association with types of chronic gastritis, and most recently, a link to Helicobacter pylori infection.
Alison Stopeck. Links Between Helicobacter pylori Infection, Cobalamin Deficiency, and Pernicious Anemia. Arch Intern Med. 2000;160(9):1229–1230. doi:10.1001/archinte.160.9.1229