"High intake of
GABA was shown to produce a significant increase in plasma growth-hormone levels (single administration of 5,000 mg) and prolactin (daily administration of 18,000 mg for four days) in one human study(1) but the clinical significance of these observations is not clear."
(1)Cavagnini F, Invitti C, Pinto M. Effect of acute and repeated administration of gamma aminobutyric acid (
GABA) on growth hormone and prolactin secretion in
man. Acta Endocrinol 1980;93:149-54.
http://www.vitacost.com/science/hn/Supp/GABA.htm