Requirements for indispensable amino acids in adult humans: longer-term amino acid kinetic study with support for the adequacy of the Massachusetts Institute of Technology amino acid requirement pattern.
Twenty young men received an L-amino acid diet, supplying 140 mg N.kg-1 x d-1 and patterned as in the Egg diet for 1 wk, and then for 3 wk either a pattern based on international recommendations (modified FAO diet; n = 7), our new amino acid requirement pattern (MIT diet; n = 7), or the egg pattern (Egg diet; n = 6). At the end of the initial week, at 1 and 3 wk with the three experimental diets, and after 3 d after return to the Egg diet, an 8-h continuous intravenous infusion with [1-13C]leucine (3 h fast, 5 h fed while subjects received hourly meals supplying the equivalent of one-twelfth the daily intake) was conducted. After 3 wk with the different diets, mean daily leucine balances were lower (P < 0.01) with the FAO diet (-160 mumol.kg-1 x d-1) than with the MIT diet (-15 mumol.kg-1 x d-1). Together with changes in plasma amino acid profiles [eg, methionine increased (P < 0.05) during feeding with the FAO and Egg diets but not with the MIT diet; increased proline concentrations during the fed state (P < 0.05) with the FAO diet but not with the MIT or Egg diets] we interpret these findings to indicate that the FAO diet is not capable of maintaining amino acid homeostasis, as is the case with the MIT and Egg diets.
Marchini
J S
JS
Laboratory of Human Nutrition and Clinical Research Center, Massachusetts Institute of Technology, Cambridge 02139.
Cortiella
J
J
Hiramatsu
T
T
Chapman
T E
TE
Young
V R
VR
D000328:Adult; D000596:Amino Acids / Q000378:metabolism*; D001944:Breath Tests; D002153:Calorimetry, Indirect; D002250:Carbon Radioisotopes; D006801:Humans; D007930:Leucine / Q000493:pharmacokinetics; D008297:Male; D013058:Mass Spectrometry; D008962:Models, Theoretical; D009584:Nitrogen / Q000502:physiology; D009751:Nutritional Requirements
D000596:Amino Acids; D002250:Carbon Radioisotopes; D007930:Leucine; D009584:Nitrogen