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.

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    The fact that cereals produce rickets in young animals was demonstrated in 1920 when it was found that increasing the amount of these substances in diets which were deficient in the antirachitic vitamin led to an increase in the intensity of ty rickets [Mellanby, 1920]. At that time the explanation offered to account for the phenomenon was that cereals increased the rate of growth of animals, yet they could not at the same time supply the necessary elements to ensure the perfect formation of the bones. The greater the rate of growth induced by feeding more cereal, the greater was the demand for the food factors necessary for bone and tooth calcification and the more abnormal therefore became the condition of the bones and teeth. While this explanation undoubtedly accounted in part for the rachitogenic action of cereals in these experiments, it soon became clear that it could not explain all the facts, especially the observation that different cereals eaten in amounts which produced similar rates of growth produced widely different intensities of rickets. Experiment showed that cereals could be graded in their rickets-producing effect, oatmeal being the worst of those tested, white flour and rice having the least interfering effect on calcification, and whole-meal wheat flour being more rachitogenic than white flour [Mellanby, 1922; 1925]. It has long been known, of course, that the degree of calcification produced by a diet depends in part on the amounts and relative proportions of Ca and P in the diet. Examination of these graded effects of cereals on bone and tooth calcification, however, soon revealed that they could not be explained simply in terms of Ca and P contents or by the different ratios of these elements in cereals. On the whole, the cereals with the largest amounts of Ca and P, such as oatmeal, maize and wheat germ, caused the lowest Ca and P retention in the bones and teeth—an enigma which threw doubt on the nutritional significance of the values obtained by chemical analysis for the total Ca and P contents of foods. In view of these facts it seemed clear that the rachitogenic action of cereals could not be fully explained by their growth-promoting action or mineral content, and it was concluded that some of the more strongly rachitogenic of the group, especially oatmeal and maize, must contain an active rickets-producing substance. This view of the presence of some positive, toxic, rickets-producing factor in cereals was strengthened by the observation that the effect could be destroyed by boiling the cereal for some time with dilute HC1 [Mellanby, 1925]. On feeding the neutralized product (the NaCl content of the control diets being, of course, made up to the same value), it was found that the rachitogenic action of the cereal had been largety destroyed. Attempts made to isolate such a factor, and to demonstrate its action when separated from the cereal, at that time failed. In spite of this failure, some of the conditions which affected the activity of the rachitogenic substance in cereals were disclosed and these facts were useful in determining the further progress of the work. ( 1660 )