The Relation of the Fat-Soluble Factor to Rickets and Growth in Pigs

Abstract

CLINICAL and experimental observations tend to show that diet plays an im- portant part in the etiology of rickets and much of the evidence obtained by the clinician goes further to demonstrate that the results obtained with certain oils and fats in the prophylactic and the curative treatment of the disease is quite marked. The recent experimental work of Mellanby [1918 and 1919] throws a very interesting light on the therapeutic value of fats and oils. Mellanby has shown that by keeping puppies on a certain basal diet, definite rickets could be induced in these animals and that the disease could be prevented or cured by the addition of certain substances, mostly oils and fats, to the basal diet. Of the substances which were capable of producing this bene- ficial effect the majority were found to be identical with those which contain the fat-soluble A factor. This important observation suggested the possibility that the fat-soluble factor or another accessory factor closely associated with it was concerned in the prophylaxis of rickets. However, investigations carried out clinically and experimentally in order to test this theory of the etiology of rickets have yielded results from which no definite conclusions can yet be drawn. Hess and Unger [1920] from observations made on groups of infants receiving diets some of which were rich, others deficient in the fat-soluble factor, could not obtain any definite evidence that the rickets which developed in some of their patients could be traced to an accessory factor deficiency. Harden and The animals declined, but no rickets deve- loped. Mackay [1921] fed kittens on a diet deficient in this-factor, but other- wise theoretically adequate, with the result that the animals ceased growing.