GABA (gamma-aminobutyric acid) is the main calming (inhibitory) messenger in the brain. As a supplement, made by fermentation or found naturally in some foods, it is taken for stress and sleep, although it is not clear how much reaches the brain.
Also known as: gamma-aminobutyric acid, PharmaGABA.
There is no intake value or upper limit, and the reviews below do not settle on a single amount studied.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling.
Does it reach the brain? A 2015 review (Boonstra) says it has long been thought that GABA cannot cross the blood-brain barrier, that studies on this are contradictory, and that how GABA supplements might work is unknown. It found some evidence of a calming effect, but noted most of it came from researchers with a potential conflict of interest.
A 2020 systematic review of 14 placebo-controlled human trials (Hepsomali) found limited evidence for stress benefits and very limited evidence for sleep benefits, and said more studies are needed before conclusions can be drawn. The sources here do not describe side effects or drug interactions.
We could not find a single published half-life or time to peak for GABA that applies to a supplement dose, so we do not list one.
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