GABA - Gamma Aminobutyric AcidThe amino acid Gamma Aminobutyric Acid (GABA) is a neurotransmitter that plays a key role in growth hormone (GH) secretion. Twenty years ago, a group of Italian researchers published several studies showing GABA’s unique ability to significantly increase circulating GH levels (1,2). Despite these promising results, virtually no other research has examined the effects of GABA supplementation on GH release, until recently.

There are at least seven known isotopes of GH found in circulation in humans, only a few of these are considered bioactive (5). GH is a powerful anabolic hormone that builds lean mass, melts body fat, and enhances athletic performance. While the Italian researchers did not assess bioactive GH concentrations, the ability of GABA to raise circulating GH concentrations makes it a serious supplement for strength athletes and others that want increased GH output.

How GABA works . . .

GABA is the only supplement available today with evidence of its effectiveness to increase circulating GH levels. GABA does not cross the blood-brain barrier (i.e., it cannot be transported efficiently into the brain from the bloodstream) (4). Therefore, GABA supplementation does not increase GABA concentrations in the brain. However, pharmacological (5 gram) doses of GABA are shown to produce highly significant (P<0.001) increases in GH in healthy humans (1,2). In relation to neurotransmission, GABA is released continuously from nerve terminals (3). GABA transporters have been identified on neurons and astrocytes. It appears that GABA is taken up predominantly by neurons and thought to inhibit somatostatin neurons in the preoptic/anterior hypothalamic area to facilitate GH release (3,4,5)

The latest research . . .

This year at the American College of Sports Medicine’s Annual meeting, a group of scientists from the University of Gainesville, Florida presented research on the effects of GABA supplementation in bodybuilders undertaking resistance training (6).

In this research, 3 grams of GABA produced significantly higher GH increases from resistance training.

Seven male bodybuilders (21-28 yrs) participated in four randomly ordered testing conditions, 1) at rest following ingestion of a placebo, 2) at rest following ingestion of 3-grams of GABA, 3) consumption of GABA (3-grams) immediately before resistance training exercise and 4) consumption of a placebo before resistance training. The GABA and placebo were provided in capsules.

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The exercised trials involved the subjects performing 1 set to failure using 70% of their one-rep max in a series of multi-joint exercises. Blood samples were taken every 15 minutes for a total of 90 minutes after intake of the supplements. A high-quality analysis procedure (ELISA) determined serum GH and immunofunctional GH (IFGH) – a bioactive form of GH.

Results showed when taken before resistance training, GABA produced significantly higher GH levels after the workout. Higher growth hormone levels after your workout create an anabolic environment for much greater recovery support and lean muscle growth.

What these results mean to athletes . . .

This is the first study to examine the effects of GABA supplementation on blood GH levels after exercise. In this research, GABA supplementation (3-grams) produced significantly better GH increases from resistance training. These results are very interesting as consistently higher GH secretion after training may have a very positive effect on long-term strength and muscle gains.

The anabolic stimulus of resistance training lasts for up to 48 hours following the workout. The bio-activity or inactive of the GH molecule in circulation could alter over this time frame scientists aren’t sure. Higher concentrations of GH may amplify the anabolic effect of intense training and provide better strength and muscle mass gains over the long-term.

Based on this research, a small dose of GABA just before your workout may result in significantly higher GH secretion during and after training. Athletes and bodybuilders that compete in drug tested events can use GABA to boost GH levels naturally. In any athlete’s language, this supplement approach is definitely worth incorporating into your training program.


1. J Clin Endocr Metab, 51, 789-792, 1980.
2. Acta Endocrinol Feb;93(2):149-54, 1980.
3. J Neurochem, Vol. 73, No. 4, 1335-1342, 1999.
4. Brain Res. May 21;374(1):119-2, 1986.
5. Physiol. Rev. 79: 511-607, 1999.
6. Med Sci Sports Exerc 35;5:A1500, 2003.

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The Latest Research on GABA: The Growth Hormone Booster.

by AST Sports Science time to read: 3 min