Dorothy is 67 years old and lives alone with her Maltese Terrier named Fred. Her breakfast consists of mainly toast and tea. She has usually has a tomato sandwich with a spinach salad for lunch. For dinner she gets meals-on-wheels delivered but gives the meat to Fred. She goes to her doctor because she is feeling very tired lately and she feels numbness and tingling in her legs. On her blood work her red blood cells are enlarged (macrocytic). What disease has she likely developed? What vitamin/mineral is she deficient in?