PHYTIC ACID AND THE PREPARATION OF FOOD

Abstract

NOW that something definite is known about phytie acid metabolism and about the extent to which this compound interferes with the absorption of calcium, the quantities in our daily food have become almost as important a nutritional counter as the amounts of calcium. In fact, following Harrison and Mellanby's work on dogs¹,.and the experiments on men and women which have been carried out in this Department², it has become clear that the phytie acid/calcium ratio determines whether a diet will promote the absorption of calcium or facilitate the production of rickets. Foods have been analysed for calcium and for phytie acid, but there is another aspect of the matter which has not yet received the attention it deserves. It is known that the rat possesses a digestive enzyme which will hydrolyse phytie acid³. It is thought that other animals have not; and consequently it is generally assumed in human nutrition that the phytic acid in wheat and other natural foodstuffs can be broken down bnly by the bacteria in the intestine. There is, however, a phytase in wheat, and the purpose of this note is to show that this enzyme is active in commercial flours, and that it may destroy phytie acid during the accepted cooking processes.