That macrocytic anemia in relapse is promptly relieved by either the parenteral or the oral administration of synthetic folic acid was reported by Spies, Vilter, Koch and Caldwell1 in November 1945. The following month Vilter, Spies and Koch2 reported another series of cases in which these results were confirmed. At the same time Spies, López, Menédez, Minnich and Koch3 reported that the macrocytic anemia of tropical sprue found in Cuba responds in a similar manner.
The present report, which is a tentative evaluation of the status of folic acid as a therapeutic agent, is presented because of the large number of requests for information from physicians regarding the use of folic acid as a therapeutic agent. It has been disheartening to write to so many physicians that leukemia, aplastic anemia and some of the anemias of undetermined origin do not respond specifically to this substance.
SPIES TD. EFFECT OF FOLIC ACID ON PERSONS WITH MACROCYTIC ANEMIA IN RELAPSE. JAMA. 1946;130(8):474-477. doi:10.1001/jama.1946.02870080008002