Experimental and clinical evidence indicate that either oral or parenteral therapy can be used effectively for the treatment of vitamin B12 deficiency. However, when vitamin B12 is being used for its pharmacological effects, in the vast majority of cases only parenteral administration appears to be effective.
Alan R. Gaby, MD
1. Lederle FA. Oral cobalamin for pernicious anemia. Medicine's best kept secret? JAMA 1991;265:94-95
2. Kuzminski AM , et al. Effective treatment of cobalamin deficiency with oral cobalamin. Blood 1998;92:1191-1198