What is gamma-aminobutyric acid (GABA) as a therapeutic supplement?

Overview

The substance gamma-aminobutyric acid (GABA) is a neurotransmitter, a chemical used by the human nervous
system to send messages and modulate its own function. GABA acts in an inhibitory
manner, tending to calm the nerves. Drugs in the benzodiazepine-receptor-agonist
(BzRA) family (a family that includes true benzodiazepines such as Valium, as
well as related drugs such as Ambien and Lunesta) exert their effect by
facilitating the ability of GABA to bind to receptor sites in the brain. In turn,
this leads to relaxation, relief from anxiety, induction of sleep, and suppression
of seizure activity.

When GABA is taken orally, GABA levels in the brain do not increase, presumably because the substance itself cannot pass the blood-brain barrier and enter the central nervous system. For this reason, oral GABA supplements cannot replicate the effect of tranquilizing drugs, even though they work through a GABA-related mechanism. GABA supplements can affect the peripheral nervous system, however, as well as any other part of the body not protected by the blood-brain barrier. Some evidence suggests that orally ingested GABA might cause physiological changes that lead to benefit for hypertension.

Requirements and Sources

GABA is not a required nutrient, and it is not found to any extent in food.
However, certain probiotics in the Lactobacillus family can
be induced to produce GABA as they ferment milk and soy products. GABA supplements
can also be created entirely synthetically.

Therapeutic Dosages

In the best-designed study of GABA for reducing blood pressure, the dosage used
was 10 milligrams (mg) daily. Much higher dosages are sometimes recommended by
alternative practitioners for treating anxiety or insomnia, as
high as 1,000 mg daily, in the (probably vain) hope that some tiny amount of this
orally ingested GABA might make it into the brain.

Therapeutic Uses

As noted above, GABA is still sometimes recommended for treatment of anxiety
and insomnia, but it is almost certainly ineffective for these purposes. However,
evidence from animal studies and preliminary studies in humans hint that GABA
supplements can reduce blood pressure. In the best of the human trials,
thirty-nine people with mild hypertension were given either a
fermented milk product providing GABA, at a dose of 10 mg daily, or a placebo, for
twelve weeks. The results indicated that GABA modestly decreased blood pressure
levels. However, this study was small and suffered from significant problems in
design. Additional research will be necessary before GABA can be considered an
effective treatment for high blood pressure.

Safety Issues

No serious adverse effects have been associated with the use of GABA. Nonetheless, comprehensive safety studies have not been performed. Maximum safe doses in young children, pregnant or nursing women, and people with severe liver or kidney disease have not been established.

Bibliography

Hirata, H., et al. “Hypotensive Effect of Fermented Milk Containing Gamma-Aminobutyric Acid (GABA) in Subjects with High Normal Blood Pressure.” Journal of the Japanese Society for Food Science and Technology 51 (2004): 79-86.

Inoue, K., et al. “Blood-Pressure-Lowering Effect of a Novel Fermented Milk Containing Gamma-Aminobutyric Acid (GABA) in Mild Hypertensives.” European Journal of Clinical Nutrition 57 (2003): 490-495.

Park, K. B., and S. H. Oh. “Production of Yogurt with Enhanced Levels of Gamma-Aminobutyric Acid and Valuable Nutrients Using Lactic Acid Bacteria and Germinated Soybean Extract.” Bioresource Technology 98 (2007): 1675-1679.