one viewer wrote, i have been diagnosed with per nishs anemia. i was told that my stomach lining is very thin. what can i do to prevent serious complications? >> i love this topic. anemia is something you cannot ignore. you need something called intrinsic factor in the stomach to combine with b12 so when they go in the bowels they would get absorbed. what causes this problem? if there is some immune disease in the family, type 1 diabetes, thyroid problems, you may have this kind of intrinsic factor. if you have krohn's, you may have the problem. a lot of people are taking xanax or tums, et cetera. >> zantac. >> zantac, so a lot of meat that has b12. when you have vitamin b12 deficiency, you're tired, you're fatigued, you may be depressed. i know mark probably treats this in the office with antibiotics. >> can you take a b12 supplement over the counter? >> first of all, we have to find out if you have it. you come to the doctor's office and we test you for it. we have to differentiate between this, perniciou srs anemia, and there are shots for it.