GABA is a key calming neurotransmitter in the human nervous system that is also found in some foods. GABA acts to relax the nervous system by preventing overstimulation.

GABA has a number of effects on the immune cells such as activation or suppression of cytokine secretion, modification of cell proliferation and GABA can even affect migration of the cells. The immune cells encounter GABA when released by the immune cells themselves or when the immune cells enter the brain.