title: The acute effects of a low and high dose of oral L-arginine supplementation in young active males at rest.
abstract: 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 ∼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.
authors.affiliation: Faculty of Physical Education and Recreation, University of Alberta, Edmonton, AB T6G 2H9, Canada. scforbes@ualberta.ca
authors.forename: Scott C
authors.initials: SC
authors.lastname: Forbes
authors.forename: Gordon J
authors.initials: GJ
authors.lastname: Bell
mesh_terms: D000284:Administration, Oral; D000328:Adult; D001120:Arginine / Q000008:administration & dosage / Q000494:pharmacology*; D018592:Cross-Over Studies; D019587:Dietary Supplements; D004311:Double-Blind Method; D013006:Growth Hormone / Q000097:blood; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D009566:Nitrates / Q000097:blood; D009573:Nitrites / Q000097:blood; D012146:Rest; D055815:Young Adult
chemical_list: D009566:Nitrates; D009573:Nitrites; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D001120:Arginine