In general, there is limited human research on oral supplementation with GABA. A few small studies have found improvements in sleep quality and markers of stress, as measured by questionnaires, heart rate variability, and cortisol, following supplementation with GABA, but other studies have not.[1] 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[2] and mood during stressful tasks.[3] These effects might be relevant to people with schizophrenia and mood disorders because GABA levels in the brain and neural signaling processes activated by GABA are altered in these conditions.[4][5][1][6][7][8] 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,[9][10] but it remains to be studied whether this effect can actually help improve exercise performance in the heat.
One resistance training intervention found that daily supplementation with whey protein (10 grams per day) and GABA (100 milligrams per day) increased fat-free mass more than whey protein alone,[11] but muscle strength was not affected. Further studies are needed to confirm this finding.