GABA (Gamma-aminobutyric acid)
Japanese: GABA（γ-アミノ酪酸）
An inhibitory neurotransmitter known for its relaxation effects. Fermentation increases its content in foods.
GABA is an amino acid that functions as an inhibitory neurotransmitter in the brain, calming neural excitation and reportedly contributing to relaxation and blood pressure reduction.
Fermented foods tend to be rich in GABA—detected in miso, pickles, germinated brown rice, and yogurt. This occurs because lactic acid bacteria and koji mold decarboxylate glutamic acid into GABA.
Recently, lactic acid bacteria strains with high GABA-producing capacity have attracted attention for functional food applications. Whether orally consumed GABA crosses the blood-brain barrier remains debated, with some researchers suggesting the enteric nervous system is the primary pathway. While functionality is still under study, GABA is a fascinating substance that fermentation 'creates.'