A study appeared in Blood (August 15, 1998;92(4):1191-1198) that looked at 38 patients who were diagnosed with vitamin B12 deficiency. The patients were given either a 1 milligram intramuscular injection of cobalamin (on days 1, 3, 7, 10, 14, 21, 30, 60 and 90) or a two milligram oral dose for four months. After four months of therapy, cobalamin levels where higher , and homocysteine levels and methylmalonic acid levels were lower in the group receiving the oral therapy.