Abstract
The observations here reported comprise a part of a more comprehensive study undertaken jointly by the Departments of Medicine and Pediatrics of the Johns Hopkins University on experimental amino acid deficiencies in man. The purpose of this study was twofold. It was felt desirable to determine human amino acid requirements by direct observations on man, rather than by inferences based on animal experiments, since it is now known that even closely related animal species differ in their amino acid requirements. A second purpose was to discover whether deficiencies of particular amino acids produced characteristic pathological changes which could be recognized by clinical or laboratory technics. It seemed probable that, in certain parts of the world at least, specific amino acid deficiencies might be present, and that a familiarity with the picture, such as could be obtained in an experimental study, would be of aid in recognizing and treating them.
The present report deals with the nitrogen balance of 4 normal adult males, who ingested a diet deficient in tryptophane for periods of 2 to 5 weeks. The experimental diet consisted of fats, starch, sugar and certain fruits and vegetables selected for their low protein content (tomatoes, mushrooms, carrots, asparagus, apples, oranges, etc.). Of the total nitrogen ingested only 10% was in the form of food proteins, the remaining 90% being supplied as a mixture of amino acids devoid of tryptophane (an acid hydrolysate of casein to which 1% cystine was added). The total nitrogen intake was maintained throughout the experiment at 0.1 g per kilo per day. The intake of non-nitrogenous food was identical for all subjects, providing approximately 800 calories of fat and 1500 calories of carbohydrate per day. The total caloric intake varied in the different subjects between 2400 and 2700 calories per day.
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