GABA is the major inhibitory neurotransmitter in the central nervous system. It fulfills a number of functions in the brain and affects nonneuronal tissues outside the brain. GABA regulates many depressive and sedative actions and is critical for relaxation.<a href="#ref-1" id="ref-link-1" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Olsen RW, Sieghart W. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18790874" target="\_blank" rel="noopener noreferrer"&gt;International Union of Pharmacology. LXX. Subtypes of gamma-aminobutyric acid(A) receptors: classification on the basis of subunit composition, pharmacology, and function. Update.
&lt;/a&gt;&lt;/p&gt;Pharmacol Rev (2008-Sep)&lt;/div&gt;'>[1]</a><a href="#ref-2" id="ref-link-2" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Sieghart W, Savić MM. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/30275042" target="\_blank" rel="noopener noreferrer"&gt;International Union of Basic and Clinical Pharmacology. CVI: GABA Receptor Subtype- and Function-selective Ligands: Key Issues in Translation to Humans.
&lt;/a&gt;&lt;/p&gt;Pharmacol Rev (2018-Oct)&lt;/div&gt;'>[2]</a><a href="#ref-3" id="ref-link-3" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Ngo DH, Vo TS. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31344785" target="\_blank" rel="noopener noreferrer"&gt;An Updated Review on Pharmaceutical Properties of Gamma-Aminobutyric Acid.
&lt;/a&gt;&lt;/p&gt;Molecules (2019-Jul-24)&lt;/div&gt;'>[3]</a><a href="#ref-4" id="ref-link-4" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Petroff OA. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/12467378" target="\_blank" rel="noopener noreferrer"&gt;GABA and glutamate in the human brain.
&lt;/a&gt;&lt;/p&gt;Neuroscientist (2002-Dec)&lt;/div&gt;'>[4]</a> Consequently, several drugs that resemble the structure of GABA (e.g., <a href="https://www.drugs.com/baclofen.html">baclofen</a>, <a href="https://www.drugs.com/gabapentin.html">gabapentin</a>, and <a href="https://www.drugs.com/pregabalin.html">pregabalin</a>) have been developed to treat seizures and convulsions. GABA is also involved in the neural regulation of visual tasks and emotion processing.<a href="#ref-5" id="ref-link-5" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kiemes A, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33762983" target="\_blank" rel="noopener noreferrer"&gt;GABA, Glutamate and Neural Activity: A Systematic Review With Meta-Analysis of Multimodal H-MRS-fMRI Studies.
&lt;/a&gt;&lt;/p&gt;Front Psychiatry (2021)&lt;/div&gt;'>[5]</a>

What is GABA?

In general, there is limited human research on oral supplementation with GABA. A few small studies have found improvements in <a href="/outcomes/sleep-quality/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Sleep Quality&lt;/h6&gt;&lt;p&gt;Sleep quality refers to how restful your sleep is — how well it rejuvenates your mind and body. For you to feel rested in the morning, your sleep must have sufficient duration and quality. Like insufficient sleep duration, poor sleep quality can start a cascade of health issues. You may want to read our ten tips for better sleep.&lt;/p&gt;&lt;/div&gt;">sleep quality</a> and markers of <a href="/conditions/stress/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Stress&lt;/h6&gt;&lt;p&gt;Stress (particularly distress) is excessive stimulation of the body's resources that eventually leads to negative symptoms such as fatigue or depression. Several supplements, such as adaptogens, are thought to reduce the development of stress.&lt;/p&gt;&lt;/div&gt;">stress</a>, as measured by questionnaires, <a href="/outcomes/heart-rate-variability/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Heart Rate Variability&lt;/h6&gt;&lt;p&gt;Heart rate variability refers to the differences in time between each heartbeat.&lt;/p&gt;&lt;/div&gt;">heart rate variability</a>, and <a href="/outcomes/cortisol/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Cortisol&lt;/h6&gt;&lt;p&gt;Cortisol is a hormone that mediates the stress response and sleep-wake cycle, being high in the morning and (hopefully) low in the evening. It triggers gluconeogenesis and a variety of other catabolic reactions. It isn't necessarily harmful or needing to be minimized, but excessive and chronically high cortisol can cause insulin resistance, endothelial dysfunction, reduced immune function, and other negative effects.&lt;/p&gt;&lt;/div&gt;">cortisol</a>, following supplementation with GABA, but other studies have not.<a href="#ref-6" id="ref-link-6" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Piril Hepsomali, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33041752" target="\_blank" rel="noopener noreferrer"&gt;Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review
&lt;/a&gt;&lt;/p&gt;Front Neurosci (2020 Sep 17)&lt;/div&gt;'>[6]</a> Therefore, it’s not currently possible to draw firm conclusions about the effect of GABA on these outcomes. 
Some studies find that supplementation with GABA improves some aspects of visual attention<a href="#ref-7" id="ref-link-7" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Leonte A, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29222993" target="\_blank" rel="noopener noreferrer"&gt;Supplementation of gamma-aminobutyric acid (GABA) affects temporal, but not spatial visual attention.
&lt;/a&gt;&lt;/p&gt;Brain Cogn (2018-Feb)&lt;/div&gt;'>[7]</a> and <a href="/outcomes/mood/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Mood&lt;/h6&gt;&lt;p&gt;These are supplements which may affect anxiety, depression, and their subclinical and related conditions.&lt;/p&gt;&lt;/div&gt;">mood</a> during stressful tasks.<a href="#ref-8" id="ref-link-8" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Yoto A, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/22203366" target="\_blank" rel="noopener noreferrer"&gt;Oral intake of γ-aminobutyric acid affects mood and activities of central nervous system during stressed condition induced by mental tasks.
&lt;/a&gt;&lt;/p&gt;Amino Acids (2012-Sep)&lt;/div&gt;'>[8]</a> These effects might be relevant to people with <a href="/conditions/schizophrenia/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Schizophrenia&lt;/h6&gt;&lt;p&gt;Schizophrenia is a brain condition that may cause auditory and/or visual hallucinations, delusions, difficulties with emotions and cognition, and verbal communication problems. These symptoms manifest between the ages of 16 and 30.&lt;/p&gt;&lt;/div&gt;">schizophrenia</a> and mood disorders because GABA levels in the brain and neural signaling processes activated by GABA are altered in these conditions.<a href="#ref-9" id="ref-link-9" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Reddy-Thootkur M, Kraguljac NV, Lahti AC. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/32107102" target="\_blank" rel="noopener noreferrer"&gt;The role of glutamate and GABA in cognitive dysfunction in schizophrenia and mood disorders - A systematic review of magnetic resonance spectroscopy studies.
&lt;/a&gt;&lt;/p&gt;Schizophr Res (2022-Nov)&lt;/div&gt;'>[9]</a><a href="#ref-10" id="ref-link-10" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Kumar V, Vajawat B, Rao NP. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/32067569" target="\_blank" rel="noopener noreferrer"&gt;Frontal GABA in schizophrenia: A meta-analysis of H-MRS studies.
&lt;/a&gt;&lt;/p&gt;World J Biol Psychiatry (2021-Jan)&lt;/div&gt;'>[10]</a><a href="#ref-6" id="ref-link-6" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Piril Hepsomali, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33041752" target="\_blank" rel="noopener noreferrer"&gt;Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review
&lt;/a&gt;&lt;/p&gt;Front Neurosci (2020 Sep 17)&lt;/div&gt;'>[6]</a><a href="#ref-11" id="ref-link-11" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Frajman A, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/32376074" target="\_blank" rel="noopener noreferrer"&gt;Gene expression meta-analysis reveals the down-regulation of three GABA receptor subunits in the superior temporal gyrus of patients with schizophrenia.
&lt;/a&gt;&lt;/p&gt;Schizophr Res (2020-Jun)&lt;/div&gt;'>[11]</a><a href="#ref-12" id="ref-link-12" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Romeo B, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29252166" target="\_blank" rel="noopener noreferrer"&gt;Meta-analysis of central and peripheral γ-aminobutyric acid levels in patients with unipolar and bipolar depression.
&lt;/a&gt;&lt;/p&gt;J Psychiatry Neurosci (2018-Jan)&lt;/div&gt;'>[12]</a><a href="#ref-13" id="ref-link-13" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Schür RR, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/27145016" target="\_blank" rel="noopener noreferrer"&gt;Brain GABA levels across psychiatric disorders: A systematic literature review and meta-analysis of (1) H-MRS studies.
&lt;/a&gt;&lt;/p&gt;Hum Brain Mapp (2016-Sep)&lt;/div&gt;'>[13]</a> However, studies determining the effect of supplementation with GABA in people with these conditions is currently lacking. 
A single dose of GABA (1 gram) taken orally has been shown to blunt the rise in core temperature at rest and during exercise in the heat,<a href="#ref-14" id="ref-link-14" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Miyazawa T, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/22738209" target="\_blank" rel="noopener noreferrer"&gt;Oral administration of γ-aminobutyric acid affects heat production in a hot environment in resting humans.
&lt;/a&gt;&lt;/p&gt;J Physiol Anthropol (2012-Feb-29)&lt;/div&gt;'>[14]</a><a href="#ref-15" id="ref-link-15" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Miyazawa T, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/20088409" target="\_blank" rel="noopener noreferrer"&gt;Effect of oral administration of GABA on temperature regulation in humans during rest and exercise at high ambient temperature.
&lt;/a&gt;&lt;/p&gt;Osaka City Med J (2009-Dec)&lt;/div&gt;'>[15]</a> but it remains to be studied whether this effect can actually help improve exercise performance in the heat.
One <a href="/other/resistance-training/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Resistance Training&lt;/h6&gt;&lt;p&gt;Resistance training, also known as strength training, is a term used to describe a form of exercise where muscles must contract against an external force.&lt;/p&gt;&lt;/div&gt;">resistance training</a> intervention found that daily supplementation with <a href="/supplements/whey-protein/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Whey Protein&lt;/h6&gt;&lt;p&gt;The protein in cow’s milks is 80% casein and 20% whey protein. Whey protein powder is extremely popular due to its high digestibility and well-researched benefits for both muscle gain and fat loss.&lt;/p&gt;&lt;/div&gt;">whey protein</a> (10 grams per day) and GABA (100 milligrams per day) increased <a href="/outcomes/muscle-mass/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Lean Mass&lt;/h6&gt;&lt;p&gt;Your lean mass is your weight minus your fat mass. It includes your bones, organs, and water, although bone is sometimes excluded. Fat-free mass differs by excluding essential fats found in cell membranes; these are included in lean mass.&lt;/p&gt;&lt;/div&gt;">fat-free mass</a> more than whey protein alone,<a href="#ref-16" id="ref-link-16" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Sakashita M, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31143310" target="\_blank" rel="noopener noreferrer"&gt;Oral Supplementation Using Gamma-Aminobutyric Acid and Whey Protein Improves Whole Body Fat-Free Mass in Men After Resistance Training.
&lt;/a&gt;&lt;/p&gt;J Clin Med Res (2019-Jun)&lt;/div&gt;'>[16]</a> but <a href="/conditions/muscle-strength/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Muscle Strength&lt;/h6&gt;&lt;p&gt;Muscle strength refers to the ability to produce force and is often measured using a &lt;em&gt;1-repetition maximum&lt;/em&gt; (1RM) test. Increases in maximum strength are best promoted by regularly lifting loads ≥ 80% of 1RM.&lt;/p&gt;&lt;/div&gt;">muscle strength</a> was not affected. Further studies are needed to confirm this finding.

What are GABA’s main benefits?

In the few human studies that exist, a single oral dose of GABA (3–5 grams) was found to increase circulating <a href="/outcomes/growth-hormone/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Growth Hormone&lt;/h6&gt;&lt;p&gt;Growth hormone (GH) is a peptide hormone that regulates growth in youth, and in adults is thought to promote fat loss and longevity. Increasing growth hormone should improve these goals, but supplements are currently lacklustre.&lt;/p&gt;&lt;/div&gt;">growth hormone</a> concentrations at rest<a href="#ref-26" id="ref-link-26" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Cavagnini F, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/7419665" target="\_blank" rel="noopener noreferrer"&gt;Effect of gamma-aminobutyric acid on growth hormone and prolactin secretion in man: influence of pimozide and domperidone.
&lt;/a&gt;&lt;/p&gt;J Clin Endocrinol Metab (1980-Oct)&lt;/div&gt;'>[26]</a><a href="#ref-27" id="ref-link-27" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Cavagnini F, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/7376786" target="\_blank" rel="noopener noreferrer"&gt;Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man.
&lt;/a&gt;&lt;/p&gt;Acta Endocrinol (Copenh) (1980-Feb)&lt;/div&gt;'>[27]</a><a href="#ref-28" id="ref-link-28" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Powers ME, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18091016" target="\_blank" rel="noopener noreferrer"&gt;Growth hormone isoform responses to GABA ingestion at rest and after exercise.
&lt;/a&gt;&lt;/p&gt;Med Sci Sports Exerc (2008-Jan)&lt;/div&gt;'>[28]</a> and in response to resistance exercise.<a href="#ref-28" id="ref-link-28" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Powers ME, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18091016" target="\_blank" rel="noopener noreferrer"&gt;Growth hormone isoform responses to GABA ingestion at rest and after exercise.
&lt;/a&gt;&lt;/p&gt;Med Sci Sports Exerc (2008-Jan)&lt;/div&gt;'>[28]</a> An increase in resting growth hormone concentrations has also been found in participants with no health conditions following intravenous injection with <a href="https://www.drugs.com/baclofen.html">baclofen</a>, a drug that activates GABAB receptors,<a href="#ref-29" id="ref-link-29" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Volpi R, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/1625515" target="\_blank" rel="noopener noreferrer"&gt;Failure of the gamma-aminobutyric acid (GABA) derivative, baclofen, to stimulate growth hormone secretion in heroin addicts.
&lt;/a&gt;&lt;/p&gt;Life Sci (1992)&lt;/div&gt;'>[29]</a> but not <a href="https://www.drugs.com/alprazolam.html">alprazolam</a>, a GABAA receptor activator.<a href="#ref-30" id="ref-link-30" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Hedrington MS, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/27217489" target="\_blank" rel="noopener noreferrer"&gt;Effects of γ-Aminobutyric Acid A Receptor Activation on Counterregulatory Responses to Subsequent Exercise in Individuals With Type 1 Diabetes.
&lt;/a&gt;&lt;/p&gt;Diabetes (2016-Sep)&lt;/div&gt;'>[30]</a><a href="#ref-31" id="ref-link-31" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Hedrington MS, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/25901095" target="\_blank" rel="noopener noreferrer"&gt;Effects of Antecedent GABA A Receptor Activation on Counterregulatory Responses to Exercise in Healthy Man.
&lt;/a&gt;&lt;/p&gt;Diabetes (2015-Sep)&lt;/div&gt;'>[31]</a> However, the growth hormone-increasing effects of GABA<a href="#ref-27" id="ref-link-27" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Cavagnini F, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/7376786" target="\_blank" rel="noopener noreferrer"&gt;Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man.
&lt;/a&gt;&lt;/p&gt;Acta Endocrinol (Copenh) (1980-Feb)&lt;/div&gt;'>[27]</a> and baclofen<a href="#ref-32" id="ref-link-32" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Cavagnini F, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/903403" target="\_blank" rel="noopener noreferrer"&gt;Effects of a gamma aminobutyric acid (GABA) derivative, baclofen, on growth hormone and prolactin secretion in man.
&lt;/a&gt;&lt;/p&gt;J Clin Endocrinol Metab (1977-Sep)&lt;/div&gt;'>[32]</a> attenuate with daily use.
Overall, the effects of GABA on circulating growth hormone concentrations are complex. Although high-dose supplementation with GABA can significantly increase growth hormone levels, the effects attenuate rapidly, within a few days.<a href="#ref-27" id="ref-link-27" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Cavagnini F, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/7376786" target="\_blank" rel="noopener noreferrer"&gt;Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man.
&lt;/a&gt;&lt;/p&gt;Acta Endocrinol (Copenh) (1980-Feb)&lt;/div&gt;'>[27]</a> It is not currently clear whether the effects of GABA on human growth hormone have meaningful effects on health or athletic performance.

Does GABA increase growth hormone?

Ingested GABA does not appear to reach the brain in appreciable amounts,<a href="#ref-17" id="ref-link-17" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Löscher W, Frey HH. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/6801203" target="\_blank" rel="noopener noreferrer"&gt;Transport of GABA at the blood-CSF interface.
&lt;/a&gt;&lt;/p&gt;J Neurochem (1982-Apr)&lt;/div&gt;'>[17]</a><a href="#ref-18" id="ref-link-18" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Al-Sarraf H. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/12480126" target="\_blank" rel="noopener noreferrer"&gt;Transport of 14C-gamma-aminobutyric acid into brain, cerebrospinal fluid and choroid plexus in neonatal and adult rats.
&lt;/a&gt;&lt;/p&gt;Brain Res Dev Brain Res (2002-Dec-15)&lt;/div&gt;'>[18]</a><a href="#ref-19" id="ref-link-19" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;K Kuriyama, P Y Sze. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/5569303" target="\_blank" rel="noopener noreferrer"&gt;Blood-brain barrier to H3-gamma-aminobutyric acid in normal and amino oxyacetic acid-treated animals
&lt;/a&gt;&lt;/p&gt;Neuropharmacology (1971 Jan)&lt;/div&gt;'>[19]</a><a href="#ref-20" id="ref-link-20" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;A Krantis. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/6475496" target="\_blank" rel="noopener noreferrer"&gt;The involvement of GABA-transaminase in the blood-brain barrier to radiolabelled GABA
&lt;/a&gt;&lt;/p&gt;Acta Neuropathol (1984)&lt;/div&gt;'>[20]</a> meaning oral supplementation can’t be assumed to replicate the effects of GABA as a neurotransmitter. However, the main drawback is that few studies have examined the effect of oral supplementation with GABA in humans. Furthermore, the specific effect of GABA is often difficult to determine because many human studies examine the effect of eating GABA-containing foods, like tea or rice, rather than the effect of oral supplementation with GABA alone.<a href="#ref-6" id="ref-link-6" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Piril Hepsomali, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33041752" target="\_blank" rel="noopener noreferrer"&gt;Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review
&lt;/a&gt;&lt;/p&gt;Front Neurosci (2020 Sep 17)&lt;/div&gt;'>[6]</a> Consequently, further clinical trials specifically using GABA are needed to fully understand its effects.
Oral supplementation with GABA appears to be fairly safe and well-tolerated, with no evidence of toxicity in animal studies<a href="#ref-21" id="ref-link-21" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Takeshima K, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/24530859" target="\_blank" rel="noopener noreferrer"&gt;Subchronic toxicity evaluation of γ-aminobutyric acid (GABA) in rats.
&lt;/a&gt;&lt;/p&gt;Food Chem Toxicol (2014-Jun)&lt;/div&gt;'>[21]</a><a href="#ref-22" id="ref-link-22" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Oketch-Rabah HA, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34444905" target="\_blank" rel="noopener noreferrer"&gt;United States Pharmacopeia (USP) Safety Review of -Aminobutyric Acid (GABA).
&lt;/a&gt;&lt;/p&gt;Nutrients (2021-Aug-10)&lt;/div&gt;'>[22]</a> or serious side effects in human studies.<a href="#ref-23" id="ref-link-23" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Martin A, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/36566274" target="\_blank" rel="noopener noreferrer"&gt;A randomized trial of oral gamma aminobutyric acid (GABA) or the combination of GABA with glutamic acid decarboxylase (GAD) on pancreatic islet endocrine function in children with newly diagnosed type 1 diabetes.
&lt;/a&gt;&lt;/p&gt;Nat Commun (2022-Dec-24)&lt;/div&gt;'>[23]</a><a href="#ref-22" id="ref-link-22" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Oketch-Rabah HA, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/34444905" target="\_blank" rel="noopener noreferrer"&gt;United States Pharmacopeia (USP) Safety Review of -Aminobutyric Acid (GABA).
&lt;/a&gt;&lt;/p&gt;Nutrients (2021-Aug-10)&lt;/div&gt;'>[22]</a><a href="#ref-24" id="ref-link-24" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Yoon S, Byun JI, Shin WC. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/35796273" target="\_blank" rel="noopener noreferrer"&gt;Efficacy and Safety of Low-Dose Gamma-Aminobutyric Acid From Unpolished Rice Germ as a Health Functional Food for Promoting Sleep: A Randomized, Double-Blind, Placebo-Controlled Trial.
&lt;/a&gt;&lt;/p&gt;J Clin Neurol (2022-Jul)&lt;/div&gt;'>[24]</a><a href="#ref-14" id="ref-link-14" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Miyazawa T, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/22738209" target="\_blank" rel="noopener noreferrer"&gt;Oral administration of γ-aminobutyric acid affects heat production in a hot environment in resting humans.
&lt;/a&gt;&lt;/p&gt;J Physiol Anthropol (2012-Feb-29)&lt;/div&gt;'>[14]</a><a href="#ref-15" id="ref-link-15" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Miyazawa T, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/20088409" target="\_blank" rel="noopener noreferrer"&gt;Effect of oral administration of GABA on temperature regulation in humans during rest and exercise at high ambient temperature.
&lt;/a&gt;&lt;/p&gt;Osaka City Med J (2009-Dec)&lt;/div&gt;'>[15]</a><a href="#ref-16" id="ref-link-16" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Sakashita M, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31143310" target="\_blank" rel="noopener noreferrer"&gt;Oral Supplementation Using Gamma-Aminobutyric Acid and Whey Protein Improves Whole Body Fat-Free Mass in Men After Resistance Training.
&lt;/a&gt;&lt;/p&gt;J Clin Med Res (2019-Jun)&lt;/div&gt;'>[16]</a><a href="#ref-6" id="ref-link-6" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Piril Hepsomali, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/33041752" target="\_blank" rel="noopener noreferrer"&gt;Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review
&lt;/a&gt;&lt;/p&gt;Front Neurosci (2020 Sep 17)&lt;/div&gt;'>[6]</a> However, abdominal discomfort, headache, and drowsiness has been documented following supplementation with GABA.<a href="#ref-25" id="ref-link-25" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Byun JI, et al. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/29856155" target="\_blank" rel="noopener noreferrer"&gt;Safety and Efficacy of Gamma-Aminobutyric Acid from Fermented Rice Germ in Patients with Insomnia Symptoms: A Randomized, Double-Blind Trial.
&lt;/a&gt;&lt;/p&gt;J Clin Neurol (2018-Jul)&lt;/div&gt;'>[25]</a>

What are GABA’s main drawbacks?

GABA exerts its various effects by binding to GABAA and GABAB receptors in the brain. GABA is also found outside the brain in nonneuronal tissues, including the pancreas, certain immune cells (e.g., lymphocytes), and the gastrointestinal tract. How GABA works outside the brain is an area of ongoing research.<a href="#ref-1" id="ref-link-1" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Olsen RW, Sieghart W. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/18790874" target="\_blank" rel="noopener noreferrer"&gt;International Union of Pharmacology. LXX. Subtypes of gamma-aminobutyric acid(A) receptors: classification on the basis of subunit composition, pharmacology, and function. Update.
&lt;/a&gt;&lt;/p&gt;Pharmacol Rev (2008-Sep)&lt;/div&gt;'>[1]</a><a href="#ref-2" id="ref-link-2" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Sieghart W, Savić MM. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/30275042" target="\_blank" rel="noopener noreferrer"&gt;International Union of Basic and Clinical Pharmacology. CVI: GABA Receptor Subtype- and Function-selective Ligands: Key Issues in Translation to Humans.
&lt;/a&gt;&lt;/p&gt;Pharmacol Rev (2018-Oct)&lt;/div&gt;'>[2]</a><a href="#ref-3" id="ref-link-3" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Ngo DH, Vo TS. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/31344785" target="\_blank" rel="noopener noreferrer"&gt;An Updated Review on Pharmaceutical Properties of Gamma-Aminobutyric Acid.
&lt;/a&gt;&lt;/p&gt;Molecules (2019-Jul-24)&lt;/div&gt;'>[3]</a><a href="#ref-4" id="ref-link-4" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Petroff OA. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/12467378" target="\_blank" rel="noopener noreferrer"&gt;GABA and glutamate in the human brain.
&lt;/a&gt;&lt;/p&gt;Neuroscientist (2002-Dec)&lt;/div&gt;'>[4]</a><a href="#ref-4" id="ref-link-4" class="ref-link popover" data-tooltip='&lt;div&gt;&lt;p class="mb-3"&gt;Petroff OA. &lt;a href="https://pubmed.ncbi.nlm.nih.gov/12467378" target="\_blank" rel="noopener noreferrer"&gt;GABA and glutamate in the human brain.
&lt;/a&gt;&lt;/p&gt;Neuroscientist (2002-Dec)&lt;/div&gt;'>[4]</a>

How does GABA work?

GABA

Sleep

International Union of Pharmacology. LXX. Subtypes of gamma-aminobutyric acid(A) receptors: classification on the basis of subunit composition, pharmacology, and function. Update.

International Union of Basic and Clinical Pharmacology. CVI: GABA Receptor Subtype- and Function-selective Ligands: Key Issues in Translation to Humans.

An Updated Review on Pharmaceutical Properties of Gamma-Aminobutyric Acid.

GABA and glutamate in the human brain.

GABA, Glutamate and Neural Activity: A Systematic Review With Meta-Analysis of Multimodal H-MRS-fMRI Studies.

Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review

Supplementation of gamma-aminobutyric acid (GABA) affects temporal, but not spatial visual attention.

Oral intake of γ-aminobutyric acid affects mood and activities of central nervous system during stressed condition induced by mental tasks.

The role of glutamate and GABA in cognitive dysfunction in schizophrenia and mood disorders - A systematic review of magnetic resonance spectroscopy studies.

Frontal GABA in schizophrenia: A meta-analysis of H-MRS studies.

Gene expression meta-analysis reveals the down-regulation of three GABA receptor subunits in the superior temporal gyrus of patients with schizophrenia.

Meta-analysis of central and peripheral γ-aminobutyric acid levels in patients with unipolar and bipolar depression.

Brain GABA levels across psychiatric disorders: A systematic literature review and meta-analysis of (1) H-MRS studies.

Oral administration of γ-aminobutyric acid affects heat production in a hot environment in resting humans.

Effect of oral administration of GABA on temperature regulation in humans during rest and exercise at high ambient temperature.

Oral Supplementation Using Gamma-Aminobutyric Acid and Whey Protein Improves Whole Body Fat-Free Mass in Men After Resistance Training.

Transport of GABA at the blood-CSF interface.

Transport of 14C-gamma-aminobutyric acid into brain, cerebrospinal fluid and choroid plexus in neonatal and adult rats.

Blood-brain barrier to H3-gamma-aminobutyric acid in normal and amino oxyacetic acid-treated animals

The involvement of GABA-transaminase in the blood-brain barrier to radiolabelled GABA

Subchronic toxicity evaluation of γ-aminobutyric acid (GABA) in rats.

United States Pharmacopeia (USP) Safety Review of -Aminobutyric Acid (GABA).

A randomized trial of oral gamma aminobutyric acid (GABA) or the combination of GABA with glutamic acid decarboxylase (GAD) on pancreatic islet endocrine function in children with newly diagnosed type 1 diabetes.

Efficacy and Safety of Low-Dose Gamma-Aminobutyric Acid From Unpolished Rice Germ as a Health Functional Food for Promoting Sleep: A Randomized, Double-Blind, Placebo-Controlled Trial.

Safety and Efficacy of Gamma-Aminobutyric Acid from Fermented Rice Germ in Patients with Insomnia Symptoms: A Randomized, Double-Blind Trial.

Effect of gamma-aminobutyric acid on growth hormone and prolactin secretion in man: influence of pimozide and domperidone.

Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man.

Growth hormone isoform responses to GABA ingestion at rest and after exercise.

Failure of the gamma-aminobutyric acid (GABA) derivative, baclofen, to stimulate growth hormone secretion in heroin addicts.

Effects of γ-Aminobutyric Acid A Receptor Activation on Counterregulatory Responses to Subsequent Exercise in Individuals With Type 1 Diabetes.

Effects of Antecedent GABA A Receptor Activation on Counterregulatory Responses to Exercise in Healthy Man.

Effects of a gamma aminobutyric acid (GABA) derivative, baclofen, on growth hormone and prolactin secretion in man.

Bill Willis

Nick Milazzo

Dmitri Barvinok

Thomas Solomon

GABA is the major inhibitory neurotransmitter in the central nervous system. It fulfills a number of functions in the brain and affects nonneuronal tissues outside the brain. GABA regulates many depressive and sedative actions and is critical for relaxation.[reference|url=https://pubmed.ncbi.nlm.nih.gov/18790874|title=International Union of Pharmacology. LXX. Subtypes of gamma-aminobutyric acid(A) receptors: classification on the basis of subunit composition, pharmacology, and function. Update.|published=2008-Sep|authors=Olsen RW, Sieghart W|journal=Pharmacol Rev|][reference|url=https://pubmed.ncbi.nlm.nih.gov/30275042|title=International Union of Basic and Clinical Pharmacology. CVI: GABA Receptor Subtype- and Function-selective Ligands: Key Issues in Translation to Humans.|published=2018-Oct|authors=Sieghart W, Savić MM|journal=Pharmacol Rev|][reference|url=https://pubmed.ncbi.nlm.nih.gov/31344785|title=An Updated Review on Pharmaceutical Properties of Gamma-Aminobutyric Acid.|published=2019-Jul-24|authors=Ngo DH, Vo TS|journal=Molecules|][reference|url=https://pubmed.ncbi.nlm.nih.gov/12467378|title=GABA and glutamate in the human brain.|published=2002-Dec|authors=Petroff OA|journal=Neuroscientist|] Consequently, several drugs that resemble the structure of GABA (e.g., <a href="https://www.drugs.com/baclofen.html">baclofen</a>, <a href="https://www.drugs.com/gabapentin.html">gabapentin</a>, and <a href="https://www.drugs.com/pregabalin.html">pregabalin</a>) have been developed to treat seizures and convulsions. GABA is also involved in the neural regulation of visual tasks and emotion processing.[reference|url=https://pubmed.ncbi.nlm.nih.gov/33762983|title=GABA, Glutamate and Neural Activity: A Systematic Review With Meta-Analysis of Multimodal H-MRS-fMRI Studies.|published=2021|authors=Kiemes A, Davies C, Kempton MJ, Lukow PB, Bennallick C, Stone JM, Modinos G|journal=Front Psychiatry|]

In general, there is limited human research on oral supplementation with GABA. A few small studies have found improvements in <a href="/outcomes/sleep-quality/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Sleep Quality&lt;/h6&gt;&lt;p&gt;Sleep quality refers to how restful your sleep is — how well it rejuvenates your mind and body. For you to feel rested in the morning, your sleep must have sufficient duration and quality. Like insufficient sleep duration, poor sleep quality can start a cascade of health issues. You may want to read our ten tips for better sleep.&lt;/p&gt;&lt;/div&gt;">sleep quality</a> and markers of <a href="/conditions/stress/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Stress&lt;/h6&gt;&lt;p&gt;Stress (particularly distress) is excessive stimulation of the body's resources that eventually leads to negative symptoms such as fatigue or depression. Several supplements, such as adaptogens, are thought to reduce the development of stress.&lt;/p&gt;&lt;/div&gt;">stress</a>, as measured by questionnaires, <a href="/outcomes/heart-rate-variability/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Heart Rate Variability&lt;/h6&gt;&lt;p&gt;Heart rate variability refers to the differences in time between each heartbeat.&lt;/p&gt;&lt;/div&gt;">heart rate variability</a>, and <a href="/outcomes/cortisol/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Cortisol&lt;/h6&gt;&lt;p&gt;Cortisol is a hormone that mediates the stress response and sleep-wake cycle, being high in the morning and (hopefully) low in the evening. It triggers gluconeogenesis and a variety of other catabolic reactions. It isn't necessarily harmful or needing to be minimized, but excessive and chronically high cortisol can cause insulin resistance, endothelial dysfunction, reduced immune function, and other negative effects.&lt;/p&gt;&lt;/div&gt;">cortisol</a>, following supplementation with GABA, but other studies have not.[reference|url=https://pubmed.ncbi.nlm.nih.gov/33041752|title=Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review|published=2020 Sep 17|authors=Piril Hepsomali, John A Groeger, Jun Nishihira, Andrew Scholey|journal=Front Neurosci|] Therefore, it’s not currently possible to draw firm conclusions about the effect of GABA on these outcomes. 
Some studies find that supplementation with GABA improves some aspects of visual attention[reference|url=https://pubmed.ncbi.nlm.nih.gov/29222993|title=Supplementation of gamma-aminobutyric acid (GABA) affects temporal, but not spatial visual attention.|published=2018-Feb|authors=Leonte A, Colzato LS, Steenbergen L, Hommel B, Akyürek EG|journal=Brain Cogn|] and <a href="/outcomes/mood/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Mood&lt;/h6&gt;&lt;p&gt;These are supplements which may affect anxiety, depression, and their subclinical and related conditions.&lt;/p&gt;&lt;/div&gt;">mood</a> during stressful tasks.[reference|url=https://pubmed.ncbi.nlm.nih.gov/22203366|title=Oral intake of γ-aminobutyric acid affects mood and activities of central nervous system during stressed condition induced by mental tasks.|published=2012-Sep|authors=Yoto A, Murao S, Motoki M, Yokoyama Y, Horie N, Takeshima K, Masuda K, Kim M, Yokogoshi H|journal=Amino Acids|] These effects might be relevant to people with <a href="/conditions/schizophrenia/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Schizophrenia&lt;/h6&gt;&lt;p&gt;Schizophrenia is a brain condition that may cause auditory and/or visual hallucinations, delusions, difficulties with emotions and cognition, and verbal communication problems. These symptoms manifest between the ages of 16 and 30.&lt;/p&gt;&lt;/div&gt;">schizophrenia</a> and mood disorders because GABA levels in the brain and neural signaling processes activated by GABA are altered in these conditions.[reference|url=https://pubmed.ncbi.nlm.nih.gov/32107102|title=The role of glutamate and GABA in cognitive dysfunction in schizophrenia and mood disorders - A systematic review of magnetic resonance spectroscopy studies.|published=2022-Nov|authors=Reddy-Thootkur M, Kraguljac NV, Lahti AC|journal=Schizophr Res|][reference|url=https://pubmed.ncbi.nlm.nih.gov/32067569|title=Frontal GABA in schizophrenia: A meta-analysis of H-MRS studies.|published=2021-Jan|authors=Kumar V, Vajawat B, Rao NP|journal=World J Biol Psychiatry|][reference|url=https://pubmed.ncbi.nlm.nih.gov/33041752|title=Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review|published=2020 Sep 17|authors=Piril Hepsomali, John A Groeger, Jun Nishihira, Andrew Scholey|journal=Front Neurosci|][reference|url=https://pubmed.ncbi.nlm.nih.gov/32376074|title=Gene expression meta-analysis reveals the down-regulation of three GABA receptor subunits in the superior temporal gyrus of patients with schizophrenia.|published=2020-Jun|authors=Frajman A, Maggio N, Muler I, Haroutunian V, Katsel P, Yitzhaky A, Weiser M, Hertzberg L|journal=Schizophr Res|][reference|url=https://pubmed.ncbi.nlm.nih.gov/29252166|title=Meta-analysis of central and peripheral γ-aminobutyric acid levels in patients with unipolar and bipolar depression.|published=2018-Jan|authors=Romeo B, Choucha W, Fossati P, Rotge JY|journal=J Psychiatry Neurosci|][reference|url=https://pubmed.ncbi.nlm.nih.gov/27145016|title=Brain GABA levels across psychiatric disorders: A systematic literature review and meta-analysis of (1) H-MRS studies.|published=2016-Sep|authors=Schür RR, Draisma LW, Wijnen JP, Boks MP, Koevoets MG, Joëls M, Klomp DW, Kahn RS, Vinkers CH|journal=Hum Brain Mapp|] However, studies determining the effect of supplementation with GABA in people with these conditions is currently lacking. 
A single dose of GABA (1 gram) taken orally has been shown to blunt the rise in core temperature at rest and during exercise in the heat,[reference|url=https://pubmed.ncbi.nlm.nih.gov/22738209|title=Oral administration of γ-aminobutyric acid affects heat production in a hot environment in resting humans.|published=2012-Feb-29|authors=Miyazawa T, Kawabata T, Okazaki K, Suzuki T, Imai D, Hamamoto T, Matsumura S, Miyagawa T|journal=J Physiol Anthropol|][reference|url=https://pubmed.ncbi.nlm.nih.gov/20088409|title=Effect of oral administration of GABA on temperature regulation in humans during rest and exercise at high ambient temperature.|published=2009-Dec|authors=Miyazawa T, Kawabata T, Suzuki T, Imai D, Hamamoto T, Yoshikawa T, Miyagawa T|journal=Osaka City Med J|] but it remains to be studied whether this effect can actually help improve exercise performance in the heat.
One <a href="/other/resistance-training/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Resistance Training&lt;/h6&gt;&lt;p&gt;Resistance training, also known as strength training, is a term used to describe a form of exercise where muscles must contract against an external force.&lt;/p&gt;&lt;/div&gt;">resistance training</a> intervention found that daily supplementation with <a href="/supplements/whey-protein/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Whey Protein&lt;/h6&gt;&lt;p&gt;The protein in cow’s milks is 80% casein and 20% whey protein. Whey protein powder is extremely popular due to its high digestibility and well-researched benefits for both muscle gain and fat loss.&lt;/p&gt;&lt;/div&gt;">whey protein</a> (10 grams per day) and GABA (100 milligrams per day) increased <a href="/outcomes/muscle-mass/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Lean Mass&lt;/h6&gt;&lt;p&gt;Your lean mass is your weight minus your fat mass. It includes your bones, organs, and water, although bone is sometimes excluded. Fat-free mass differs by excluding essential fats found in cell membranes; these are included in lean mass.&lt;/p&gt;&lt;/div&gt;">fat-free mass</a> more than whey protein alone,[reference|url=https://pubmed.ncbi.nlm.nih.gov/31143310|title=Oral Supplementation Using Gamma-Aminobutyric Acid and Whey Protein Improves Whole Body Fat-Free Mass in Men After Resistance Training.|published=2019-Jun|authors=Sakashita M, Nakamura U, Horie N, Yokoyama Y, Kim M, Fujita S|journal=J Clin Med Res|] but <a href="/conditions/muscle-strength/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Muscle Strength&lt;/h6&gt;&lt;p&gt;Muscle strength refers to the ability to produce force and is often measured using a &lt;em&gt;1-repetition maximum&lt;/em&gt; (1RM) test. Increases in maximum strength are best promoted by regularly lifting loads ≥ 80% of 1RM.&lt;/p&gt;&lt;/div&gt;">muscle strength</a> was not affected. Further studies are needed to confirm this finding.

In the few human studies that exist, a single oral dose of GABA (3–5 grams) was found to increase circulating <a href="/outcomes/growth-hormone/" class="popover" data-tooltip="&lt;div&gt;&lt;h6&gt;Growth Hormone&lt;/h6&gt;&lt;p&gt;Growth hormone (GH) is a peptide hormone that regulates growth in youth, and in adults is thought to promote fat loss and longevity. Increasing growth hormone should improve these goals, but supplements are currently lacklustre.&lt;/p&gt;&lt;/div&gt;">growth hormone</a> concentrations at rest[reference|url=https://pubmed.ncbi.nlm.nih.gov/7419665|title=Effect of gamma-aminobutyric acid on growth hormone and prolactin secretion in man: influence of pimozide and domperidone.|published=1980-Oct|authors=Cavagnini F, Benetti G, Invitti C, Ramella G, Pinto M, Lazza M, Dubini A, Marelli A, Müller EE|journal=J Clin Endocrinol Metab|][reference|url=https://pubmed.ncbi.nlm.nih.gov/7376786|title=Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man.|published=1980-Feb|authors=Cavagnini F, Invitti C, Pinto M, Maraschini C, Di Landro A, Dubini A, Marelli A|journal=Acta Endocrinol (Copenh)|][reference|url=https://pubmed.ncbi.nlm.nih.gov/18091016|title=Growth hormone isoform responses to GABA ingestion at rest and after exercise.|published=2008-Jan|authors=Powers ME, Yarrow JF, McCoy SC, Borst SE|journal=Med Sci Sports Exerc|] and in response to resistance exercise.[reference|url=https://pubmed.ncbi.nlm.nih.gov/18091016|title=Growth hormone isoform responses to GABA ingestion at rest and after exercise.|published=2008-Jan|authors=Powers ME, Yarrow JF, McCoy SC, Borst SE|journal=Med Sci Sports Exerc|] An increase in resting growth hormone concentrations has also been found in participants with no health conditions following intravenous injection with <a href="https://www.drugs.com/baclofen.html">baclofen</a>, a drug that activates GABAB receptors,[reference|url=https://pubmed.ncbi.nlm.nih.gov/1625515|title=Failure of the gamma-aminobutyric acid (GABA) derivative, baclofen, to stimulate growth hormone secretion in heroin addicts.|published=1992|authors=Volpi R, Gerra G, Vourna S, Vescovi PP, Maestri D, Chiodera P, Coiro V|journal=Life Sci|] but not <a href="https://www.drugs.com/alprazolam.html">alprazolam</a>, a GABAA receptor activator.[reference|url=https://pubmed.ncbi.nlm.nih.gov/27217489|title=Effects of γ-Aminobutyric Acid A Receptor Activation on Counterregulatory Responses to Subsequent Exercise in Individuals With Type 1 Diabetes.|published=2016-Sep|authors=Hedrington MS, Mikeladze M, Tate DB, Younk LM, Davis I, Davis SN|journal=Diabetes|][reference|url=https://pubmed.ncbi.nlm.nih.gov/25901095|title=Effects of Antecedent GABA A Receptor Activation on Counterregulatory Responses to Exercise in Healthy Man.|published=2015-Sep|authors=Hedrington MS, Tate DB, Younk LM, Davis SN|journal=Diabetes|] However, the growth hormone-increasing effects of GABA[reference|url=https://pubmed.ncbi.nlm.nih.gov/7376786|title=Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man.|published=1980-Feb|authors=Cavagnini F, Invitti C, Pinto M, Maraschini C, Di Landro A, Dubini A, Marelli A|journal=Acta Endocrinol (Copenh)|] and baclofen[reference|url=https://pubmed.ncbi.nlm.nih.gov/903403|title=Effects of a gamma aminobutyric acid (GABA) derivative, baclofen, on growth hormone and prolactin secretion in man.|published=1977-Sep|authors=Cavagnini F, Invitti C, Di Landro A, Tenconi L, Maraschini C, Girotti G|journal=J Clin Endocrinol Metab|] attenuate with daily use.
Overall, the effects of GABA on circulating growth hormone concentrations are complex. Although high-dose supplementation with GABA can significantly increase growth hormone levels, the effects attenuate rapidly, within a few days.[reference|url=https://pubmed.ncbi.nlm.nih.gov/7376786|title=Effect of acute and repeated administration of gamma aminobutyric acid (GABA) on growth hormone and prolactin secretion in man.|published=1980-Feb|authors=Cavagnini F, Invitti C, Pinto M, Maraschini C, Di Landro A, Dubini A, Marelli A|journal=Acta Endocrinol (Copenh)|] It is not currently clear whether the effects of GABA on human growth hormone have meaningful effects on health or athletic performance.

Ingested GABA does not appear to reach the brain in appreciable amounts,[reference|url=https://pubmed.ncbi.nlm.nih.gov/6801203|title=Transport of GABA at the blood-CSF interface.|published=1982-Apr|authors=Löscher W, Frey HH|journal=J Neurochem|][reference|url=https://pubmed.ncbi.nlm.nih.gov/12480126|title=Transport of 14C-gamma-aminobutyric acid into brain, cerebrospinal fluid and choroid plexus in neonatal and adult rats.|published=2002-Dec-15|authors=Al-Sarraf H|journal=Brain Res Dev Brain Res|][reference|url=https://pubmed.ncbi.nlm.nih.gov/5569303|title=Blood-brain barrier to H3-gamma-aminobutyric acid in normal and amino oxyacetic acid-treated animals|published=1971 Jan|authors=K Kuriyama, P Y Sze|journal=Neuropharmacology|][reference|url=https://pubmed.ncbi.nlm.nih.gov/6475496|title=The involvement of GABA-transaminase in the blood-brain barrier to radiolabelled GABA|published=1984|authors=A Krantis|journal=Acta Neuropathol|] meaning oral supplementation can’t be assumed to replicate the effects of GABA as a neurotransmitter. However, the main drawback is that few studies have examined the effect of oral supplementation with GABA in humans. Furthermore, the specific effect of GABA is often difficult to determine because many human studies examine the effect of eating GABA-containing foods, like tea or rice, rather than the effect of oral supplementation with GABA alone.[reference|url=https://pubmed.ncbi.nlm.nih.gov/33041752|title=Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review|published=2020 Sep 17|authors=Piril Hepsomali, John A Groeger, Jun Nishihira, Andrew Scholey|journal=Front Neurosci|] Consequently, further clinical trials specifically using GABA are needed to fully understand its effects.
Oral supplementation with GABA appears to be fairly safe and well-tolerated, with no evidence of toxicity in animal studies[reference|url=https://pubmed.ncbi.nlm.nih.gov/24530859|title=Subchronic toxicity evaluation of γ-aminobutyric acid (GABA) in rats.|published=2014-Jun|authors=Takeshima K, Yamatsu A, Yamashita Y, Watabe K, Horie N, Masuda K, Kim M|journal=Food Chem Toxicol|][reference|url=https://pubmed.ncbi.nlm.nih.gov/34444905|title=United States Pharmacopeia (USP) Safety Review of -Aminobutyric Acid (GABA).|published=2021-Aug-10|authors=Oketch-Rabah HA, Madden EF, Roe AL, Betz JM|journal=Nutrients|] or serious side effects in human studies.[reference|url=https://pubmed.ncbi.nlm.nih.gov/36566274|title=A randomized trial of oral gamma aminobutyric acid (GABA) or the combination of GABA with glutamic acid decarboxylase (GAD) on pancreatic islet endocrine function in children with newly diagnosed type 1 diabetes.|published=2022-Dec-24|authors=Martin A, Mick GJ, Choat HM, Lunsford AA, Tse HM, McGwin GG, McCormick KL|journal=Nat Commun|][reference|url=https://pubmed.ncbi.nlm.nih.gov/34444905|title=United States Pharmacopeia (USP) Safety Review of -Aminobutyric Acid (GABA).|published=2021-Aug-10|authors=Oketch-Rabah HA, Madden EF, Roe AL, Betz JM|journal=Nutrients|][reference|url=https://pubmed.ncbi.nlm.nih.gov/35796273|title=Efficacy and Safety of Low-Dose Gamma-Aminobutyric Acid From Unpolished Rice Germ as a Health Functional Food for Promoting Sleep: A Randomized, Double-Blind, Placebo-Controlled Trial.|published=2022-Jul|authors=Yoon S, Byun JI, Shin WC|journal=J Clin Neurol|][reference|url=https://pubmed.ncbi.nlm.nih.gov/22738209|title=Oral administration of γ-aminobutyric acid affects heat production in a hot environment in resting humans.|published=2012-Feb-29|authors=Miyazawa T, Kawabata T, Okazaki K, Suzuki T, Imai D, Hamamoto T, Matsumura S, Miyagawa T|journal=J Physiol Anthropol|][reference|url=https://pubmed.ncbi.nlm.nih.gov/20088409|title=Effect of oral administration of GABA on temperature regulation in humans during rest and exercise at high ambient temperature.|published=2009-Dec|authors=Miyazawa T, Kawabata T, Suzuki T, Imai D, Hamamoto T, Yoshikawa T, Miyagawa T|journal=Osaka City Med J|][reference|url=https://pubmed.ncbi.nlm.nih.gov/31143310|title=Oral Supplementation Using Gamma-Aminobutyric Acid and Whey Protein Improves Whole Body Fat-Free Mass in Men After Resistance Training.|published=2019-Jun|authors=Sakashita M, Nakamura U, Horie N, Yokoyama Y, Kim M, Fujita S|journal=J Clin Med Res|][reference|url=https://pubmed.ncbi.nlm.nih.gov/33041752|title=Effects of Oral Gamma-Aminobutyric Acid (GABA) Administration on Stress and Sleep in Humans: A Systematic Review|published=2020 Sep 17|authors=Piril Hepsomali, John A Groeger, Jun Nishihira, Andrew Scholey|journal=Front Neurosci|] However, abdominal discomfort, headache, and drowsiness has been documented following supplementation with GABA.[reference|url=https://pubmed.ncbi.nlm.nih.gov/29856155|title=Safety and Efficacy of Gamma-Aminobutyric Acid from Fermented Rice Germ in Patients with Insomnia Symptoms: A Randomized, Double-Blind Trial.|published=2018-Jul|authors=Byun JI, Shin YY, Chung SE, Shin WC|journal=J Clin Neurol|]

GABA exerts its various effects by binding to GABAA and GABAB receptors in the brain. GABA is also found outside the brain in nonneuronal tissues, including the pancreas, certain immune cells (e.g., lymphocytes), and the gastrointestinal tract. How GABA works outside the brain is an area of ongoing research.[reference|url=https://pubmed.ncbi.nlm.nih.gov/18790874|title=International Union of Pharmacology. LXX. Subtypes of gamma-aminobutyric acid(A) receptors: classification on the basis of subunit composition, pharmacology, and function. Update.|published=2008-Sep|authors=Olsen RW, Sieghart W|journal=Pharmacol Rev|][reference|url=https://pubmed.ncbi.nlm.nih.gov/30275042|title=International Union of Basic and Clinical Pharmacology. CVI: GABA Receptor Subtype- and Function-selective Ligands: Key Issues in Translation to Humans.|published=2018-Oct|authors=Sieghart W, Savić MM|journal=Pharmacol Rev|][reference|url=https://pubmed.ncbi.nlm.nih.gov/31344785|title=An Updated Review on Pharmaceutical Properties of Gamma-Aminobutyric Acid.|published=2019-Jul-24|authors=Ngo DH, Vo TS|journal=Molecules|][reference|url=https://pubmed.ncbi.nlm.nih.gov/12467378|title=GABA and glutamate in the human brain.|published=2002-Dec|authors=Petroff OA|journal=Neuroscientist|][reference|url=https://pubmed.ncbi.nlm.nih.gov/12467378|title=GABA and glutamate in the human brain.|published=2002-Dec|authors=Petroff OA|journal=Neuroscientist|]

GABA

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