Growth Hormone & L-Arginine
Arginine affects many different physiological processes. Taking arginine supplements improves your health, according to an March 2010 report in the "Journal of Cardiovascular Pharmacology and Therapeutics." Arginine-induced increases in human growth hormone, HGH, may mediate these effects. Your pituitary gland releases HGH to facilitate tissue repair, so increasing growth hormone levels with arginine may help you heal. Yet, arginine can cause side effects in some people; thus, talk to your doctor before taking amino acid supplements.
Short-Term Arginine Increases HGH
Many substances increase growth hormone but different mechanisms mediate these changes. Arginine, for example, increases growth hormone by blocking a natural inhibitor of HGH, according to a February 2002 report in the "European Journal of Endocrinology." This effect might occur immediately after arginine intake or it might take hours to appear. A study presented in the February 1999 issue of "Growth Hormone and IGF Research" addressed this question in healthy men. Volunteers received a 30-minute infusion of either arginine or saline. Relative to a placebo, the supplement triggered an immediate increase in growth hormone. This finding suggests that arginine immediately blocks somatostatin - the natural inhibitor of growth hormone.
Long-Term Arginine Increases HGH
Some studies have shown that the short-term effects of arginine dissipate with time. A June 2009 report in "Fundamental and Clinical Pharmacology" revealed that HGH remained unchanged during a month of arginine infusion in healthy adults. Yet, data from more controlled studies testing animals contrast this finding. An experiment described in the June 2011 edition of the "Neuroscience Bulletin" measured arginine-induced changes in growth hormone in rats. The rodents received daily infusions of the supplement or a placebo for a month. Animals given arginine had higher levels of growth hormone at the end of the study. The supplement also had anabolic effects as it increased the animals' bone size. Additional testing remains necessary to resolve these discrepancies.
Arginine Increases HGH during Exercise
Arginine also affects HGH during some types of stress. A November 1996 report in the "European Journal of Endocrinology" showed that intentionally lowering the blood sugar levels of health volunteers receiving arginine did not enhance HGH levels. Yet, taking arginine during intense exercise appears to reliably increase growth hormone. An investigation offered in the February 2011 issue of the "Journal of Nutrition" looked at the impact of a single bout of exercise. Participants received arginine or placebo while weight lifting. The supplement, relative to a placebo, further enhanced the normal exercise-induced increase in HGH. Arginine intake did not cause allergic reactions.
Arginine Reveals HGH Deficiency
The reliable increase in growth hormone due to ingesting arginine can serve as a diagnostic marker. Clinicians consider patients not showing arginine-induced increases in HGH to have a pituitary malfunction, according to a February 2008 review in "Growth Hormone and IGF Research." Interestingly, different HGH responses to arginine might help doctors make an accurate diagnosis. An experiment published in the April 2005 edition of "Clinical Endocrinology" tested this hypothesis in patients with Parkinson's disease or multiple system atrophy. It is often difficult for clinicians to distinguish between these two medical conditions. In the study, participants received arginine during a single testing session. This treatment caused large HGH increases in healthy controls and in patients with Parkinson's disease. Yet, patients with multiple system atrophy showed a much smaller response.
