TENTATIVE APPRAISAL OF VITAMIN B12 AS A THERAPEUTIC AGENT

In the antiquity of many races there is evidence that liver was used to relieve illness. The modern epoch of its therapeutic use was opened when Minot and Murphy discovered that the eating of liver could be effective in producing remissions in persons with pernicious anemia in relapse.¹ Many of the patients soon complained about the amount of liver it was necessary to ingest, however, and the efforts of many investigators were directed toward producing potent liver extracts. These extracts have been studied and used extensively in clinical medicine; yet the pathogenesis of macrocytic anemia has remained far from clear.

Two advances were reported recently from our clinic. The first of these was the observation that pteroylglutamic acid (folic acid) produced a hemopoietic response in persons with certain types of macrocytic anemia in relapse.² The second observation was that 5-methyl uracil (thymine), an entirely different chemical compound, was