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BACKGROUND Data on the protein requirements of elderly adults are limited, because it is impractical to conduct repeated nitrogen balance protocols in these vulnerable humans. OBJECTIVE This study was designed to determine the dietary protein requirement of elderly women by using the recently developed minimally invasive indicator amino acid oxidation(More)
The activity of lysine α-ketoglutarate reductase (LKR), the initial enzyme in the principal pathway of lysine catabolism, is a primary determinant of whole-body lysine status. Past research indicated that LKR activity was predominantly hepatic; recent in vivo data suggest that other tissues can also catabolize lysine. The hypothesis of this investigation(More)
BACKGROUND The current estimated protein requirements are based on the nitrogen balance method, which has many limitations. An alternate approach is needed to permit a reevaluation of protein requirements. OBJECTIVE The objective was to determine protein requirements in men by using the indicator amino acid oxidation technique. DESIGN Eight healthy men(More)
The indicator amino acid oxidation (IAAO) method is based on the concept that when 1 indispensable amino acid (IDAA) is deficient for protein synthesis, then all other IDAA, including the indicator amino acid, will be oxidized. With increasing intakes of the limiting amino acid, IAAO will decrease, reflecting increasing incorporation into protein. Once the(More)
PURPOSE OF REVIEW To discuss recent amino acid requirement studies in adult humans and school-age children, primarily determined using the indicator amino acid oxidation technique. RECENT FINDINGS Using the minimally invasive indicator amino acid oxidation model, requirements for most indispensable amino acids have been defined in adult humans. The(More)
BACKGROUND The current Dietary Reference Intake (DRI) recommendations for protein requirements in children are based on a factorial estimate and have not been directly determined. OBJECTIVE The objective of the current study was to determine the protein requirement in healthy, school-age children by measuring the oxidation of L-[1-(13)C]-phenylalanine to(More)
During the past 25 years a significant amount of research has been conducted to determine amino acid requirements in humans. This is primarily due to advancements in the application of stable isotopes to examine amino acid requirements. The indicator amino acid oxidation (IAAO) method has emerged as a robust and minimally invasive technique to identify(More)
BACKGROUND Leucine has been suggested to improve athletic performance. Therefore, the branched-chain amino acids (BCAAs), especially leucine, are popular as dietary supplements in strength-training athletes; however, the intake of leucine in excess of requirements raises concerns regarding adverse effects. Currently, the tolerable upper intake level (UL)(More)
BACKGROUND Studies on protein requirements in vulnerable groups such as older adults are few, and results are conflicting. OBJECTIVE The main objective of this study was to determine the protein requirements of free-living women >65 y by measuring the oxidation of l-[1-(13)C]phenylalanine to (13)CO2 in response to graded intakes of protein. METHODS(More)
Leucine is purported to improve athletic performance. Therefore, the BCAA, especially leucine, are popular as dietary supplements among strength-training athletes. There are, however, concerns regarding possible adverse effects of excessive leucine intake. The objective of the current study was to determine the metabolic and adverse effects of the acute(More)