Also known as gamma-aminobutyric acid, GABA is a neurotransmitter responsible for mediating neuronal activity.
During development, it functions mainly as an excitatory neurotransmitter. In the adult central nervous system, its function turns to inhibitory.
GABA neurotransmitters are located in the central nervous system, the peripheral nervous system and in nonneuronal tissues.
GABA is made from glutamate by glutamic acid decarboxylase (GAD), and its mode of action is through triggering of GABA(A), GABA (B), and GABA(C) receptors.
Compelling evidence shows there are advantages to maintaining healthy GABA levels.
GABA’s ability to influence growth hormone concentrations has been the subject of several clinical studies. One recent experiment shows its effects on growth hormone at rest and post-exercise.
Researchers recruited 11 resistance trained men in a double-blind, randomized, placebo-controlled, cross over study. The test subjects supplemented GABA or a placebo before exercise and rest. Researchers retrieved blood samples at 15, 30, 45, 60, 75, and 90 minutes after ingestion.
While GABA supplementation increased resting immunofunctional GH (irGH) and immunoreactive growth hormone (ifGH) concentrations, researchers note exercise and GABA administration resulted in 200% greater irGH and 175% greater ifGH concentrations than the exercise and placebo combination at 30 minutes post ingestion.
Evidence surrounding GABA’s ability to lower blood pressure is promising.
Patients with mild hypertension were given fermented milk containing GABA or a placebo for 12 out of 14 weeks. Results show marked decreases in blood pressure during weeks 2-4, and researchers note it “remained decreased throughout the 12-week intake period. Systolic blood pressure and diastolic blood pressure values were markedly different from baseline levels and the placebo group.
GABA is also studied for its ability to combat anxiety and depression as researchers note it is regulates multiple psychological and physiological actions.
Evidence reveals anxiety disorders and depression “share a GABAergic deficit as a common pathophysiology,” and medical authorities indicate new evidence continues to support the GABA hypothesis of depression.
-  Li K. Xu E. “The role and the mechanism of gamma-aminobutyric acid during central nervous system development.” Neurosci Bull. 2008 Jun;24(3):195-200.
-  Watanabe M, et al. “GABA and GABA receptors in the central nervous system and other organs.” Int Rev Cytol. 2002; 213:1-47.
-  Martin DL, Rimvall K. “Regulation of gamma-aminobutyric acid synthesis in the brain.” J Neurochem. 1993 Feb;60(2):395-407.
-  Power ME, et al. “Growth hormone isoform responses to GABA ingestion at rest and after exercise.” Med Sci Sports Exerc. 2008 Jan;40(1):104-10.
-  Inoue K, Shirai T, Ochiai H, et al. “Blood-pressure-lowering effect of a novel fermented milk containing gamma-aminobutyric acid (GABA) in mild hypertensives.” Eur J Clin Nutr. 2003;57:490-495.
-  Cryan JF, Kaupmann K. “Don’t worry ‘B’ happy!: a role for GABA(B) receptors in anxiety and depression.” Trends Pharmacol Sci. 2005 Jan;26(1):36-43.
-  Hanns Mohler. “The GABA system in anxiety and depression and its therapeutic potential.” Neuropharmacology. Volume 62, Issue 1, January 2012, Pages 42-53.
-  “GABA.” NYU Langone Medical Center.
-  “GABA.” WebMD.