A method and composition for treating vitamin B12 deficiency in mammals thatfail to respond to oral vitamin B12therapy, including preparing a pharmaceutical composition for oraladministration containing vitamin B12 and at least one substanceselected from the group consisting of N-[8-(2-hydroxybenzoyl)amino]caprylicacid and its pharmaceutically acceptable salts, thenadministering the pharmaceutical composition to a subject to effectively treatthe vitamin B12 deficiency.
