On the liberation of iron from egg‐yolk by gastric juice and reducing agents

Abstract

Institute at Amsterdam. we have started an extensive investigation on some aspects of iron metabolism. It is assumed 1) that certain epithelial disorders, which form part of the so-called P 1 u m m e r -V i n s o n syndrome (hypochromic anaemia), and which often degenerate into cancer, are characterized by a low serum-iron content. As in women hypochromic anaemia and cancer, especially of the mucous membrane of mouth and gullet, often occur together.we may, by extending our knowledge of this special form of anaemia, also gain more insight into the origin of this form of cancer.If the possibility of a diet exceptionally poor in iron is precluded. a low serum-iron content must be caused by a disturbance of iron metabolism. of a nature as yet unknown. Deficient iron absorption from the intestine may be one of the possible defects, caused either by inhibition of the absorption process proper, or by decreased liberation of iron from the foodstuffs in the digestive tract (iron is only absorbed as bivalent iron). T h e latter supposition is strengthened by the fact that hypochromic anaemia is often accompanied by achylia gastrica. To investigate this point we commenced with a study on the possible liberation of iron from foods in the stomach. Numerous papers deal with the state in which iron is absorbed. but only little attention has been paid so far to the manner in which the iron contained in the foodstuffs is brought into this absorbable state. W e propose to examine this matter thoroughly. as in our opinion it offers the only possibility of detecting a possible defect in the uptake of iron from the food by anaemic subjects.Egg-yolk was chosen as the first foodstuff to be examined, as it had recently been the subiect of an interesting investigation by L e d e r e r *) and was also one of the substances examined by H e i 1 m e y e r 3 ) as to their content of "available" iron.L e d e r e r ascribes the liberation of iron to the action of an enzyme, distinct from pepsin, present in the gastric juice of normal subjects, but lacking in the gastric juice of patients suffering from hypochromic anaemia. O n the other hand H e i 1 m e y e r regards pepsin as the chief agent for liberating iron from egg-yolk. next to HCI. T h e results of our experiments are not in agreement with either of these conceptions. Neither artificial nor natural gastric juice is capable of the actions ascribed to them by L e d e r e r and by H e i 1 m e y e r. Though practically all protein had been split up by pepsin, only traces of iron could be detected in the filtrate of trichloroacetic acid precipitation. In our opinion L e d e r e r's and H e i 1 m c y e r's divergent results are caused by an error in their technique.Like L e d e r e r and H e i 1 m e y e r, we determined iron hy the o-phenantroline method:precipitation by trichloroacetic acid, addition of hydroquinone to the filtrate to reduce the E'elll-ions, addition of o-phenantroline and colorimetric measurement. Now H e i 1 m e y e r and L e d e r e r both add W vol. 6 n HCI to the react...