Known for producing a calming effect, GABA may play a major role in managing symptoms of stress, fear and anxiety. Decreased levels of GABA might be linked to several mental health conditions and neurological disorders. Some of the symptoms of GABA deficiency include lethargy, hyperactive responses, low muscle tone, slowed down mental activity and EEG abnormalities. GABA is most often used for its ability to combat anxiety. It may also contribute to lowering the risk of obesity and controlling hypertension.