Abstract
A study on the improvement of dietary protein supplemented with some essential amino acids was made on healthy 392 boys ranged from 4 to 10 years of age.The subjects were devided into two groups;the one was the institutional care children under subnormal growth and the other was the normal family boys on normal growth. Daring the fourteen months (from Oct.1958 to Dec.1959), 0.5 or 0.6 gm of DLtryptophan, L-lysine-HCl and DL-threonine singly or in combinations were- supplemen - ted as tablets daily after breakfast or lunch.To the control group of the subjects were given placebos containing lactose only.The study involved monthly measurements of body weight and length, some physical strengths, blood tests, and the surveys of ha. bitual diets.The results obtained were as follows:
1) Supplementation with tryptophan: The ratios of weight gains during 14 months to initial weight were superior by about 20 per cent in supplemented groups. From the results it was recognized that the supplement of 0.5 gm DL-tryptophan (physiologically active 0.25 gin) produced favourable effects on increase in weight, while the additional effect was not obvious in height growth.
2) Supplementation with lysine or lysine plus threonine: In supplement of 0.5 or 0.6gm L-lysine-HC1 the weight gains were 13 or 19 per cent higher than those in the control.And also the gains in height were somewhat better in supplemented groups.While it was not recognized that the lysine plus threonine supplement was more effective than the supplement of lysine only.
3) According to these results, it was estimated that the supplement of trypto-phan or lysine improved the growth rate, in particular the weight gains.But the effects on the physical strengths and on the hemoglobin and serum protein concentra-tions were not distinguished.
4) The surveys of dietary habits were carried on the school children under institutional care. The intakes of calorie and protein were estimated to be maintained on the level of Japanese standard allowances applied to the same year boys. The habitual dietary protein included relative tryptophan deficiency, while the lysine content was on the normal level.
5) It was concluded that the supplement of tryptophan or lysine to the habitual diets was effective to improve the growth rate of Japanese urban school children. Although the fact was obviously due to the increment of the essential amino acids pattern of dietaryprotein, it was not yet an easy matter to explain its theoretical grounds.
