The Effects of AMINO ACID DEFICIENCIES

I T HAS LONG been known that body weightloss and hypoproteinemia constitute thefir t signs f prote n deficien y in man and experimental animals. These results of protein deficiency may arise from a depletion of protein stores as the consequence of disease or of inadequate intake of good quality pro-teins. Hypochromic anemia generally is detectable sometime after the onset of the hypoprotein-emia and body weight loss. Also, as the pro-tein depots are restored, correction of the anemia usually precedes increases in body weight and total plasma proteins.’ Until recently, these changes in man have been assessed primarily in terms of whole pro-teins; but with increasing knowledge of the biological behavior and composition of van-ous proteins, it has become evident that the overall nutritional value of various proteins is a characteristic of their component parts, namely, the amino acids. This newer concept led tile author and his coworkers some 10 years ago to undertake continuing studies on: (a) the amino acids essential for man; (b) the minimum require-ments of each; and (c) the clinical and labo-ratory manifestations of specific amino acid deficiencies. A partial summary of the re-sults of these investigations has been pre-sented elsewhere.2 In this report, we shall discuss some of the findings which pertain to clinical nutrition. EXPERIMENTAL ANIMALS It is obvious that time ultimate effects of a protein or amino acid deficiency had to be studied in experimental animals. For this purpose we employed a hybrid strain of al-bino and hooded Norwegian rats. The effects of protein deficiency were studied by feeding adult animals, for varying periods of time, the protein-free diet shown in Table I. This die