Phytic acid and the rickets-producing action of cereals / by Douglas Creese Harrison and Edward Mellanby.

  • Harrison, D. C. (Douglas Creese)
Date:
[1939?]
Catalogue details

Licence: In copyright

Credit: Phytic acid and the rickets-producing action of cereals / by Douglas Creese Harrison and Edward Mellanby. Source: Wellcome Collection.

    5/26 (page 1663)
    based on results obtained with the high Ca-low P diets generally used in studying rickets in rats. They attempted to extend their observations to low Ca-high P diets, but the results obtained were not definite. They suggested, however, that under such conditions the action of phytic acid might be different, and drew attention to the work of Starkenstein [1914] on the possible action of phytic acid in precipitating Ca or rendering it un-ionized. Such a possibility seemed much more in accordance with the observations of Mellanby, particularly with the fact that adding Ca to the diet counteracts the rachitogenie effect of the cereal. Indeed, with this possibility in mind, we carried out experiments in which we tried to isolate the rickets-producing factor of HCl-extracts of oatmeal by precipitation of the neutralized, filtered extract with CaCl2. On feeding the product after removal of Ca as oxalate, we at that time got no definite result, however, probably because the substance was given in insufficient amounts. An observation which encouraged the view that phytic acid was in some way concerned with the cereal action was the fact that Holst [1927] had shown that the active factor could be extracted from oatmeal by cold dilute HC1, for earlier workers had used this very method for extracting phytic acid from foodstuffs prior to its estimation by iron titration [Heubner & Stadler, 1914]. It seemed desirable, therefore, to try the effect of feeding phytic acid and phytin to dogs using the diets with the more natural Ca: P ratios. If then phytic acid showed a rachitogenie action and this action were due to interference with Ca absorption by precipitation of the base, it would be expected in such experi¬ ments, unlike those with a high Ca-low P ratio, that phytin, the CaMg salt, would on the other hand show little or no rachitogenie action. It will be seen in Exp. 1 that such results were actually obtained. Experimental methods In the experiments described in this paper, carried out to test the effect on the development of rickets of the addition to the diet of phytic acid compounds and fractions prepared from cereals, puppies were used, and the technique employed was essentially the same as that previously described by one of us [Mellanby, 1921; 1925]. Differences in susceptibility to rickets between different litters of animals demand that each experiment be done on dogs from a single litter, in order to justify comparison between the final conditions of the control animal or animals and those whose diet contained the various added substances. There are differences in susceptibility to rickets, even among individual members of a litter, so that repetition and confirmation of each result are essential. Where an observation has not been confirmed on a number of occasions, this fact has been stated in the text. This difference in susceptibility and, to a less extent, difference in form of manifestation of the disease, also necessitate that appraisal of the degree of rickets produced, and of the divergence from the normal, should onty be made after various forms of examination. These were (1) the appearance of the dog, including the degree of leg deformity and the size of the epiphyseal ends of the bones and the costo-chondral junctions, (2) the radiographic appearance of the epiphyseal ends of the bones, (3) the degree of calcification of bones and (4) the histological appearance of the bones. In the results recorded below only the radiographic appearances of the bones at death and the results of estimations of their Ca contents are given. In general these findings were substantiated by the appearance of the animals and the histological examination of the bones.