The Essential Amino Acid Requirements of Man

The experiments of W. C. Rose16 brought to a successful conclusion the work of Osborne and Mendel,12 and that of Willcock and Hopkins; the matter of the protein requirements in nutrition is fundamentally a question of the need for each of the indispensable amino acids (Sherman"9). While the present crisis has intensified the need for evaluating the approximate human requirements for these essentials, the recent investigations of Holt,' 6, 7 Cox,4 and Rose" are strengthening the impression that those amino acids which are essential to the rat are also indispensable to man. The calculations given below do not pertain to minimum intake of the essential amino acids, but are derived from the estimated average annual per capita consumption of food in the United States during the years 1937 to 1941 inclusive. It is well recognized that the intake of protein varies with the economic status of the group (Stiebling21). Not only is more protein consumed by the wealthier individuals, but the proportion of protein derived from animal sources is likewise increased (Orr"4). The National Research Council has stated that the daily inges-tion of 70 gm. of protein, approximately six-tenths (cf. ref. 10) of which should be derived from animal sources, is adequate for an adult man. However, the daily ration of the Army (Howe8) during the period from May to October, 1941, provided each man with 131 gm. of protein per day. The calculated daily consumption as determined from records of food supplies to the personnel of the U.S.S. Arizona (Brown8) in 1940 indicated 109 gm. of protein a day. Secretary Wickard,'3 in a radio address on December 27, 1942, stated that the average daily per capita protein consumption in the United States in 1941 was 89 gm. In good agreement with this figure is our calculation from the data presented in the August, 1942, issue2 of the Agrticultural Situation, namely, 89 gm. of protein per day. Table 1 summarizes the contribution of dietary protein by different food groups as reported in the literature and as calculated from the data in the Agricultural Situation. The findings of Sher-man18 are based upon studies of the distribution of nutrients in 224