GABA supplementation has been suggested to boost growth hormone levels in the blood following exercise.
Gamma-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the central nervous system and plays a large role in the regulation of both neuronal excitability and muscle tone. In addition, some research suggests that GABA may also influence the endocrine system by:
- Boosting growth hormone (GH). Data suggests GABA supplementation (at larger doses) might increase serum GH concentrations both at rest and following exercise.
- Regulating endocrine pancreatic function. GABA might regulate the function of the pancreas, a glandular organ whose growth has been linked to GH exposure.
Although chemically an amino acid, GABA is rarely classified as such in the scientific community and its primary referred to as a neurotransmitter. Older studies in the 1980s pointed to its benefits on growth hormone secretion, but it wasn’t until recently that additional research continued to build on these findings and continue to examine its benefits for growth hormones.
GABA does not pass the blood-brain barrier alone, making it safe to consume as a supplement without worrying about noticeable nervous system depression. However, when attached to niacin – which is water soluble – the resulting compound is picamilon, a nootropic that is believed to promote concentration and relaxation.
Research studies have connected GABA supplementation to the increased release of GH, an anabolic hormone that is integral for building lean mass, burning body fat and bolstering exercise performance. The current data is limited and still inconclusive, but its potential to lead to higher levels of GH concentrations in the blood have been making it a choice supplement for strength athletes that want to bolster their output of GH.
Did You Know?
Anxiety and sleeping medications such as benzodiazepines and Z-drugs act primarily on GABA receptors to suppress brain activity. In addition, nootropics such as phenibut also act on GABA receptors and it is this action that is believed to help the compound improve sleep quality, decrease cognitive and emotional disorders and enhance learning and memory.
How GABA Might Help for Growth Hormones
Signaling for growth hormone release in the hypothalamus
Since GABA does not cross the blood-brain barrier, supplementation does not lead to its transportation from the bloodstream into the blood, which is why using GABA supplements does not cause any noticeable nervous system inhibition. However, research has shown that five gram doses of GABA can increase growth hormone levels by a significant amount in healthy individuals. In the brain, GABA is primarily taken up by neurons and likely inhibits specific neurons in the hypothalamic area, leading to the release of growth hormones.12 In addition, more recent studies have shown that GABA consumption can increase secretion of irGH (immunoreactive growth hormone) and ifGH (immunofunctional growth hormone) at rest and following exercise, and have also highlighted a role for GABA in pituitary GH cells.3
Regulating endocrine pancreatic function
The pancreas is a glandular organ located in the abdominal cavity in humans, right behind the stomach. It is important for the production of numerous hormones such as insulin, somatostatin and glucagon, and also plays an important role in assisting in the digestion and absorption of nutrients. Research has shown that GABA plays a role in endocrine pancreatic function,4 and additional research links exposure to GH to in vitro human pancreatic growth.5
GABA Benefits, Popular Uses and Reputation for Growth Hormones
Bodybuilders have been increasingly using GABA in their stacks due to its ability to increase levels of GH in the blood. GH plays a key role in cell regeneration and growth and is necessary for increasing bone density and muscle mass. Although GH typically only stays active in the bloodstream for minutes, during this time period the liver transforms it into growth factors essential for exercise that possess important anabolic properties. Future research should focus on the various molecular isoforms of GH as current studies are limited to the main isoform.6
Animal research on the effects of GABA on growth hormones is limited, although studies have shown that:
- GABA acts on levels of corticotropin – a hormone involved in the stress response – in the hypothalamus of newborn mice.7
In order to determine if gamma aminobutyric acid (GABA) can cause the release of irGH (immunoreactive growth hormone) and ifGH (immunofunctional growth hormone) secretion both when the body is resting and during resistance exercise, researchers examined 11 men experienced in resistance training. The study was a double-blind, randomized, placebo-controlled crossover study that consisted of each participant ingesting three grams of GABA or a placebo in the form of sucrose. After ingestion, participants either conducted resistance exercise or rested. Blood sampling revealed that the group that consumed GABA and rested possessed elevated ifGH and irGH levels, with their peak concentration levels increased by a degree of four-hundred percent. In addition, those in the resistance exercise group also exhibited increased hormone concentrations, with irGH levels 200 percent higher and ifGH levels 175 percent higher compared to the placebo group.
- The researchers concluded that “that ingested GABA elevates resting and postexercise irGH and ifGH concentration,” highlighting its potential for bolstering growth hormone responses and suggest that “augmenting the postexercise irGH/ifGH response may improve resistance training-induced muscular adaptations.”8
To determine the effects of GABA consumption on the secretion of prolactin and growth hormone in humans, scientists gave five grams of the neurotransmitter to nineteen subjects. Repeated blood samples were taken from the veins both prior to and three hours following the administration of GABA. Eighteen additional subjects received a placebo in order to act as a control group. The results revealed that GABA increased levels of growth hormone in blood plasma, but not prolactin levels in blood plasma. An additional section of the experiment subjected eight individuals to a test of insulin tolerance following eighteen grams of oral GABA consumption each day for four days. These individuals exhibited a decrease in growth hormone response and increase in prolactin response to insulin hypoglycaemia.
- The researchers concluded that “pharmacological doses of GABA affect growth hormone and prolactin secretion in man,” although the exact nature of the neurotransmitter’s effects and mechanisms of action still need to be determined by further research.9
A review of the structure of GHs (growth hormones) and their action on various receptors attempts to determine if exercise can influence the synthesis of these hormones and their subsequent release into human blood. Examination of numerous studies reveals the interaction between growth hormone pieces and protein hormones, as well as the areas of action that these interactions encompass.
- The researchers claim that the review’s purpose is to “highlight human GH fragments and hypothesize their potential physiologic role,” as well as connect the breakdown of growth hormones and the impact of this process on “physical exercise and hormone multifunctionality.”10
In order to determine the role of the dopaminergic system in GABA-induced GH (growth hormone) release, researchers examined the effect of domperidone and pimozide – two compounds that inhibit this system – on GH levels in plasma after the administration of five grams of oral GABA. The results revealed that six milligrams a day of pimozide orally for four consecutive days reduced the increase in growth hormone caused by GABA administration. However, domperidone did not show these same effects.
- The researchers concluded that “GABA-stimulated GH secretion is mediated via dopamine release at a suprapituitary level.”11
Dosage for Growth Hormones
Based on the available research, five grams is the pharmaceutical dose that effectively boosts GH secretion. However, 500 mg is the most common available dosage in supplements.
GABA is typically safe to take as a supplement. However, after first taking them they may cause drowsiness the following day. If you have a history of anxiety or insomnia, consult your doctor prior to adding GABA supplements into your stack.
Supplements in Review Says
- GABA, 500 mg for growth hormones in capsule form.
Pharmacological doses of GABA (around five grams) have shown effects on growth hormones. However, the high nature of these doses and lack of conclusive evidence regarding GABAs effects on growth hormones makes it hard to recommend such a dose. We suggest using a lower dose in your stack to play it safe until research into this area is more conclusive.
500 mg in capsule form. This is the most common dosage and form for supplements of GABA.
- Müller E et al. Neuroendocrine control of growth hormone secretion. Physiol Rev. 1999 Apr;79(2):511-607 ↩
- Waagepetersen H et al. The GABA Paradox: Multiple Roles as Metabolite, Neurotransmitter, and Neurodifferentiative Agent. Journal of Neurochemistry. 1999 October;73(4):1335-1342 ↩
- Gamel-Didelon K et al. Molecular and Physiological Evidence for Functional-Aminobutyric Acid (GABA)-C Receptors in Growth Hormone-secreting Cells. The Journal of Biological Chemistry. 2003 March 25;278(22):20192-20195 ↩
- Cavagnini F et al. Effects of gamma aminobutyric acid (GABA) and muscimol on endocrine pancreatic function in man. Metabolism. 1982 Jan;31(1):73-7 ↩
- Harrison L et al. Effect of human growth hormone on human pancreatic carcinoma growth, protein, and cell cycle kinetics. J Surg Res. 1996 Mar;61(2):317-22 ↩
- Nindl B et al. Growth hormone molecular heterogeneity and exercise. Exerc Sport Sci Rev. 2003 Oct;31(4):161-6 ↩
- Stratton M et al. GABA regulates corticotropin releasing hormone levels in the paraventricular nucleus of the hypothalamus in newborn mice. Physiol Behav. 2011 Aug 3;104(2):327-33 ↩
- Powers M et al. Growth hormone isoform responses to GABA ingestion at rest and after exercise. Med Sci Sports Exerc. 2008 Jan;40(1):104-10 ↩
- Cavagnini F et al. Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man. Acta Endocrinol (Copenh). 1980 Feb;93(2):149-54 ↩
- De Palo E et al. Growth hormone isoforms, segments/fragments: does a link exist with multifunctionality? Clin Chim Acta. 2006 Feb;364(1-2):77-81 ↩
- Cavagnini F et al. Effect of gamma-aminobutyric acid on growth hormone and prolactin secretion in man: influence of pimozide and domperidone. J Clin Endocrinol Metab. 1980 Oct;51(4):789-92 ↩