amino acid
GABA
What it’s good for
2 studies · 1 supporting · 1 against
Proposed to act on blood vessels directly — a route that would not need it to reach the brain.
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: Proposed to act on gut receptors or the vagus nerve, since GABA is thought not to reach the brain.
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)
Why we could not verify it: We read the research behind this and none of it concluded that it works for this. That is a finding about the papers, not a verdict that it does nothing.
GABA for Insomnia
Not verified1 study · 0 supporting · 0 against
Why it gets suggested: Proposed to shorten how long you take to fall asleep — though whether swallowed GABA reaches the brain is disputed.
Dose: 300 mg
Tested as: GABA extracted from fermented, unpolished rice germ (15% GABA by weight), 300 mg GABA daily
Why we could not verify it: We read the research behind this and none of it concluded that it works for this. That is a finding about the papers, not a verdict that it does nothing.
1 study · 0 supporting · 0 against
Why it gets suggested: Same disputed idea as for anxiety — and the same doubt about whether it reaches the brain.
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
Why we could not verify it: We read the research behind this and none of it concluded that it works for this. That is a finding about the papers, not a verdict that it does nothing.