Not yet investigated
What we have so far
It is the brain's main inhibitory transmitter and it does not meaningfully cross the blood–brain barrier, so any effect is from the gut or from expectation.
This star is on the map because the show intends to take the question apart properly — the trials, how it is actually tested, whether the thing sold is the thing studied. That work is not done yet, and nothing here should be read as a conclusion. When the investigation is published it will appear on this page.