GABA
What it’s good for
2 studies · 1 supporting · 1 against
Proposed to lower blood pressure via peripheral vascular GABA receptors or by inhibiting angiotensin-converting enzyme (ACE) activity, a mechanism that does not require crossing the blood-brain barrier.
Dose: 10–12 mg
Tested as: GABA-enriched fermented milk (~10-12 mg GABA per 100 ml serving, 100 ml/day) in the positive trial; a competing trial tested GABA added to a vinegar/dried-bonito fermented drink and found the base drink alone worked just as well
GABA for Anxiety
Not verified1 study · 0 supporting · 0 against
Why it gets suggested: Oral GABA is proposed to act on peripheral/enteric GABA receptors or indirectly via the vagus nerve, since the blood-brain barrier is thought to block most ingested GABA from reaching brain receptors directly.
Dose: 100 mg
Tested as: synthetic GABA, single 100 mg dose dissolved in 200 ml water (also tested as GABA-enriched chocolate, 28 mg GABA per 10 g, in a separate uncontrolled-N study not included here)
GABA for Insomnia
Not verified1 study · 0 supporting · 0 against
Why it gets suggested: Proposed to shorten sleep onset via GABA-A receptor activation, though whether meaningful amounts of ingested GABA cross the blood-brain barrier to do this directly is scientifically contested.
Dose: 300 mg
Tested as: GABA extracted from fermented, unpolished rice germ (15% GABA by weight), 300 mg GABA daily
1 study · 0 supporting · 0 against
Why it gets suggested: Same disputed mechanism as for Anxiety/Insomnia above -- proposed GABA-A receptor action, undermined by the blood-brain-barrier objection.
Dose: 100 mg
Tested as: synthetic GABA capsule, 100 mg (plus small amounts of glutamic acid, other amino acids and minerals in the capsule matrix), single dose before bed