Determination of the tolerable upper intake level of leucine in acute dietary studies in young men  

Oleh:

Elango, Rajavel ; Chapman, Karen ; Rafii, Mahroukh ; Ball, Ronald O.

Jenis: Article from Journal - ilmiah internasional
Dalam koleksi: The American Journal of Clinical Nutrition vol. 96 no. 04 (Oct. 2012), page 759-767.
Topik: Urinary variables; healthy adult men

Ketersediaan

Perpustakaan FK Nomor Panggil: A07.K.2012.02 Non-tandon: 1 (dapat dipinjam: 0) Tandon: tidak ada

Lihat Detail Induk

Isi artikel

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) for leucine is unknown. Objective: The objective of the current study was to determine the UL for leucine in adult men under acute dietary conditions. Design: Five healthy adults (20–35 y) each received graded stepwise increases in leucine intakes of 50, 150, 250, 500, 750, 1000, and 1250 mg · kg-1 · d-1, which corresponded to the Estimated Average Requirement (EAR) and the EAR ×3, ×5, ×10, ×15, ×20, and ×25 in a total of 29 studies. The UL of leucine was identified by the measurement of plasma and urinary biochemical variables and changes in leucine oxidation by using l-[1-13C]-leucine. Results: A significant increase in blood ammonia concentrations above normal values, plasma leucine concentrations, and urinary leucine excretion were observed with leucine intakes >500 mg · kg-1 · d-1. The oxidation of l-[1-13C]-leucine expressed as label tracer oxidation in breath (F13CO2), leucine oxidation, and a-ketoisocaproic acid (KIC) oxidation led to different results: a plateau in F13CO2 observed after 500 mg · kg-1 · d-1, no clear plateau observed in leucine oxidation, and KIC oxidation appearing to plateau after 750 mg · kg-1 · d-1. Conclusion: On the basis of plasma and urinary variables, the UL for leucine in healthy adult men can be suggested at 500 mg · kg-1 · d-1 or ~35 g/d as a cautious estimate under acute dietary conditions.

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