GABA has many uses, with it mostly seen in sleep aids, night-time muscle builders and as a standalone to aid in anxiety. There is a study which shows that people with low GABA levels tend to correlate with insomnia. The most useful attribute for GABA is how it may reduce anxiety. Since GABA is an inhibitory neurotransmitter, it may reduce anxiety. Think of it as an ingredient that may help you wind down at the end of the night before bed.

GABA has also been shown to help increase growth hormone levels during sleep. This aids in muscle growth. Studies indicate that GABA supplementation before bed may increase growth hormone levels.  

The biggest issue with GABA has been shown to be that it is a self-regulating, and that it does not cross the blood-brain barrier very well, so supplementing with it is not going to increase GABA in your brain too much.

There are forms of GABA that have been bound, such as Phenibut and Picamilon (off the market), which are far more effective than GABA on its own.

Due to the aforementioned issues with the absorption issues with GABA, there is some evidence that taking it with a nitric oxide boosting supplements such as L-Arginine may increase its absorption.

Sleepiness seems to be the biggest side effect reported. Too much may cause nausea (at doses of 10 grams).

GABA can be taken anywhere from 750mg-2.5g per day safely, however due to its poor ability to cross the blood-brain barrier, you need to take high amounts that are inadvisable. For these reasons, straight GABA doesn’t necessarily have suggested dosage as of yet.

For an increase in growth hormone, dosages of 3-5g are recommended.

The following products contain GABA at the recommended dosage, and are recommended supplements for Fitness Informant: