The biological value of cereal proteins in human nutrition.

Abstract

Two different studies, one upon five human subjects, the other upon four, were carried on with a view to discover whether amongst the respective proteins of corn, wheat and oats, as presented to the American public in the form of cereal breakfast foods, any difference in biological value could be detected. In the first study the method of Karl Thomas 1 was followed and the so-called “metabolic nitrogen” determined in control periods of two days each. Alternating with these periods were periods of three days, during each of which the cereals successively supplied nitrogen in amount equal to the total nitrogen excreted in the control periods, or nearly so. The chief objections to the Thomas method were the tendency to diarrhoea during the control periods when the theoretical energy supply was derived solely from cornstarch, heavy cream and sugar, and the difficulty of making such a diet palatable. There was no material difference amongst the three cereals as regards biological value whichever method of calculation was employed.

In the second study control periods of three days each alternated with cereal periods of four days each; but instead of a protein-free diet, a milk-cream-fruit diet was used deriving 80 per cent of the nitrogen from milk, 10 per cent from heavy cream and 10 per cent from fruit. The tendency to diarrhoea was negligible and the diet was palatable. In the cereal periods the milk protein was replaced by cereal protein, fruit and cream remaining the same, the total calories being equalized by variations in the amount of sugar and corn starch taken. Wheat products gave slightly better replacement values than oats and corn products.