Gamma-aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the human cortex. The dietary supplement version of GABA is widely available online. Although many consumers claim to derive benefits from using these products, it is unclear whether these supplements provide benefits beyond a placebo effect. Currently, the mechanism of action behind these products is unknown.
It has long been assumed that GABA is unable to cross the blood-brain barrier (BBB), but the studies that have investigated this issue are often contradictory and have a wide range of methods used. Accordingly, future research needs to determine the effects of oral GABA administration on GABA concentrations in the human brain using, for example, magnetic resonance spectroscopy.
There is some evidence to support a sedative effect of GABA supplements, but most of this evidence has been reported by researchers with a potential conflict of interest. We suggest that any detectable effect of GABA supplements on brain and cognition may be exerted through passage of the BBB or, more indirectly, through an effect on the enteric nervous system. We conclude that the mechanism of action of GABA supplements is far from clear and that further work is needed to determine the behavioral effects of GABA.
Found at Alkohol adé (german)