Two clinical trials support GABA’s cognitive health benefits

So first off, these are two studies funded by the primary patent holder of fermented GABA, which were posted in an obscure Japanese journal. They were published by Lifescience.co.jp, which I literally have never read a study on before. I can't access the full studies to even read the study design or peer review information. The primary author, Atsushi Yamatsu, works for Pharma Foods International. Look at the other papers he has authored. Almost all deal with products that Pharma Foods International sells. Literally every red flag possible is being raised here. People should be very cautious taking these abstracts at face value.

That being said, GABA obviously has peripheral effects. There are a bunch of GABA receptors all over our bodies, not just centrally. So it would have an effect. It's just not going to have effects pertinent to CNS studies on GABA release, which is what a lot of people like to jump to. You also have probiotics in your system that affect the gut-brain-axis with GABA production. So it is pretty clear GABA has peripheral effects that can affect mood. The issue is trying to apply effects discussed in studies looking at GABA in the CNS to exogenous supplemented GABA. Also, there are situations when GABA can cross the BBB. There are also times when GABA is effluxed out of the CNS through the BBB, like in times of cerebral ischemia. So it is more complex than just "GABA can't cross the BBB." However, we should be very careful to not swing the other direction, and start applying CNS studies to peripheral GABA levels, either.