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The acute effects of a low and high dose of oral L-arginine supplementation in young active males at rest.

Author(s): Forbes SC, Bell GJ

Affiliation(s): Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB T6G 2H9, Canada. scforbes@ualberta.ca

Publication date & source: 2011-06, Appl Physiol Nutr Metab., 36(3):405-11. Epub 2011 May 16.

Publication type: Controlled Clinical Trial; Randomized Controlled Trial

L-arginine (2-amino-5-guanidinovaleric acid) is a conditionally essential amino acid. Intravenous (IV) administration of l-arginine invokes a large metabolic (nitrate/nitrite (NO(x))) and hormonal (growth hormone (GH), insulin-like growth factor 1 (IGF-1), and insulin) response; however, research examining oral l-arginine supplementation is conflicting, potentially owing to dose. The purpose of this study was examine a low and high dose of oral l-arginine on blood l-arginine, NO(x), GH, IGF-1, and insulin response. Fourteen physically active males (age: 25 +/- 5 years; weight: 78.0 +/- 8.5 kg; height: 179.4 +/- 4.7 cm) volunteered to be in a randomized, double-blind, repeated-measures study. Following an overnight fast, an IV catheter was placed in a forearm vein and a resting blood sample was drawn at approximately 0800 hours. Each subject was then provided 1 of 3 treatment conditions (placebo, low (0.075 g.kg(-1) of body mass), or high (0.15 g.kg(-1) of body mass of l-arginine)). Blood samples were drawn at 30, 60, 90, 120, and 180 min after consumption. l-arginine plasma concentrations significantly increased (p < 0.001) to a similar level at any time point in both the low- and high-dose conditions; there was no change over time in the placebo condition. There was no significant difference between conditions for NO(x), GH, IGF-1, or insulin. Based on these findings, a low dose of l-arginine was just as effective at increasing plasma l-arginine concentrations as a high dose; however, neither dose was able to promote a significant increase in NO(x), GH, IGF-1, or insulin at rest.

Page last updated: 2011-12-09

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