In the past 25 years the methods of treating the anemias have undergone striking changes which have made necessary, attention to accurate classification and grouping of patients. It is interesting that thinking in regard to the use of iron should have changed so radically at approximately the same time that treatment with liver was introduced, yet this change was the natural outcome of the extensive research carried on by Whipple and his associates and many other workers in the field. It was probably only natural, too, that after demonstration of the amazing response of pernicious anemia to liver this material should be tried in other types of anemia.
The introduction of liver extract and desiccated hog stomach for oral use and, later, of extracts for parenteral use further accelerated the tendency of members of the medical profession to use many different preparations in the treatment of anemia without paying much
Heck FJ. PROPER USE OF IRON, LIVER EXTRACT, VITAMIN B12, AND FOLIC ACID IN ANEMIAS. JAMA. 1952;148(10):783-788. doi:10.1001/jama.1952.02930100001001