Effect of a lysine-poor diet on the composition of human plasma proteins.

It has long been known that loss of body weight, negative nitrogen balance, and hypoproteinemia constitute the first signs of protein deficiency in man and experimental animals. However, in a series of studies sponsored by the Bureau of Biological Research of Rutgers University, in which six reference proteins were evaluated by different methods of assay, paradoxical findings were obtained in regard to the nutritional value of wheat gluten. Mitchell (1) reported that, by the nitrogen balance method, wheat gluten had a biological value of 40 as compared to 97 for egg albumin in the immature rat. Frost (2) by the rat depletion method found a value of 9 for wheat gluten as compared to 38 for egg albumin. Chow (3), on the other hand, by dog repletion tests obtained a value of 135 for total circulating proteins with wheat gluten as compared to 117 with egg albumin after 2 weeks, and 135 and 132 respectively after 4 weeks of repletion with these proteins. It is at once clear from the findings of these investigators that there may exist a lack of correlation between the nitrogen balance maintenance and plasma protein regenerative properties of protein foods. Since, in the evaluation of protein nutrition of population groups, the only chemical test which has been widely applied has been the determination of total serum or plasma protein levels, it seemed to us worth while to attempt the resolution of the aforementioned nutritional paradox if it existed in the human (4). The need for such a study can be readily appreciated when it is realized that wheat gluten constitutes the principal, and sometimes the only, dietary protein of the major segment of the world’s population. The investigational details of this biochemical phenomenon as it occurs in the human infant are described in bhis report.