Bodybuilders and athletes use a variety of supplements to keep themselves at the top of their game. The recent trend has been to use several amino acid supplements, most commonly L-arginine. And it has shown results to some extent. In a recent study, scientists aimed to analyze if these amino acid supplements could increase the pituitary response to hormonal stimuli.
Method of sample selection
For this study, a group of 10, moderately trained, young males were chosen as the sample population. All of the subjects underwent a detailed physical examination and a history-taking procedure to ensure they all fell under the same criteria of being healthy. Furthermore, these subjects were instructed to not take any other vitamins or mineral supplements during the course of the study fearing the effect of those on test results.
These subjects then met a nutritionist and were given strict dietary instructions to ensure similar criteria were applied to each subject.
For this study, subjects were given a 200 ml orange-flavored beverage, however one was a placebo liquid and the other was the amino acid concoction. Although this was a double-blind, controlled clinical trial, the subjects were not divided into two groups. Instead, each subject was its own compare group. As in, the subjects were given amino acid containing beverage in one session and then given a placebo beverage in the next session.
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The amino acid containing beverage included L-arginine hydrochloride, L-ornithine hydrochloride, L-Branched Chain Amino Acid (50% L-Leucine, 25% L-Isoleucine, 25% L-Valine).
After the administration of the placebo or the amino acids, the subjects then performed hormonal stimulation tests using Corticotropin-Releasing Hormone, and Gonadotropin-Releasing hormone. Eight blood samples were taken during each session, from each subject. Two samples were taken 60 mins and 30 mins before the stimulation test, one right after the IV dose of CRH and GnRH was given, and five samples were taken 15 mins, 30 mins, 45 mins, 60 mins, and 90 mins after the stimulation test.
After the stimulation tests, hormonal data for ACTH, GH, Cortisol, LH, and FSH were analyzed. ACTH, LH, and FSH showed a significant increase in interventional sessions when compared to the placebo groups. Furthermore, after supplementation, the athletes were found to have significantly higher levels of plasma testosterone and cortisol.
The increase seen in cortisol indicates a positive response to the ACTH stimulation test. Therefore it can be concluded that amino acid supplementation resulted in amplification of ACTH response in the subjects, however, it is not clear from the study if the increase was through hypothalamic or pituitary pathways modulating the hypothalamic-pituitary-adrenal axis. This warrants the need for more research into the pathway and the effect of amino acids on it.
Furthermore, the increase in testosterone indicates a response to the GnRH stimulation test in the subjects. However, like ACTH stimulation test results, the study could not pinpoint the origin of the action of these amino acids. There is a dire need for more studies to be performed on the effects of amino acids on the hypothalamic-pituitary-gonadal axis.
It can be concluded that amino acid supplements do have an effect on hormonal secretion in athletes and it is necessary for further studies to be conducted on this subject to know the safety and exact efficiency of these supplements. Also, it is recommended that supplements like these, until further research can be done, be taken under the strict supervision of a physician.
The authors of this study also suggest the central department of health and the World Anti-Doping Agency to take a revised look into the amino acid supplements for athletes in terms of doping substances.
di Luigi, L et al. “Acute amino acids supplementation enhances pituitary responsiveness in athletes.” Medicine and science in sports and exercise vol. 31,12 (1999): 1748-54. doi:10.1097/00005768-199912000-00009