Intravenous (IV) arginine invokes an increase in growth hormone (GH) concentrations, however, little is known about the impact of oral arginine ingestion on the GH response. Objective: The purpose of this study was to determine the dose of oral arginine that elicits an optimal GH response and to determine the time course of the response. Design: Eight healthy males (18-33 years - 24.8 ± 1.2 years) were studied on 4 separate occasions. Following an overnight fast at 0700 h, a catheter was placed in a forearm vein. Blood samples were taken every 10 min for 5 h. Thirty minutes after sampling was initiated, the subject ingested a dose of arginine (5, 9 or 13 g) or placebo (randomly assigned). Results: Mean resting GH values for the placebo, 5, 9 and 13 g day were 0.76, 0.67, 2.0 and 0.79 μg/L (n = 6), respectively. Integrated area under the curve was not different with 13 g (197.8 ± 65.7 min μg/L), yet it increased with 5 and 9 g compared with the placebo (301.5 ± 74.6, 524.28 ± 82.9 and 186.04 ± 47.8 min μg/L, respectively, P < 0.05). Mean peak GH levels were 2.9 ± 0.69, 3.9 ± 0.85, 6.4 ± 1.3 and 4.73 ± 1.27 μg/L on each day for the placebo, 5, 9 and 13 g days. Conclusion: In conclusion, 5 and 9 g of oral arginine caused a significant GH response. A 13 g dose of arginine resulted in considerable gastrointestinal distress in most subjects without augmentation in the GH response. The rise in GH concentration started ∼30 min after ingestion and peaked ∼60 min post ingestion.
- Amino acids
- Growth hormone
ASJC Scopus subject areas
- Endocrinology, Diabetes and Metabolism