The Quantitative Amino Acid Requirements of Young Women V. Leucine

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Abstract
The leucine requirement has been studied, with 12 young women serving as subjects on a semi-purified diet. Daily leucine intakes of 1860, 710, 620, 480, 370, 270, 170 and 95 mg were fed, and nitrogen balances determined. Not all of the subjects were studied on all of these levels. The amount of leucine needed by the different subjects for nitrogen equilibrium (excretion within 95 to 105% of the intake) varied from 170 to 710 mg daily. The 710 mg intake was for only one subject who required more than 460 mg of leucine but who was not studied on an intake of 620 mg. When 620 mg was included in a Test Mix ration with minimum amounts of 4 other essential amino acids, threonine, valine, tryptophan and phenylalanine, all 8 of the subjects fed this ration were in nitrogen equilibrium. The figure of 620 mg of L-leucine has been suggested as a tentative minimum daily requirement for young women for nitrogen equilibrium.