Chris Kresser: So, there appears to be some disagreement here, but the consensus, as far as I can understand it right now, is that GABA—most forms of GABA are large molecules that should not cross the blood-brain barrier. Actually, some practitioners have suggested that if GABA, if the patient does experience a relaxing effect from GABA when it is in its larger molecule form, then that can be a sign that they have a leaky blood-brain barrier. There are some other forms of GABA, such as the form that is in Kavinace, that do cross the blood-brain barrier, and with those, the thinking is it would be more effective for anxiety, sleep, and HPA axis dysfunction. On a practical level, I’ve had very good success with Kavinace in clinical practice for anxiety and for sleep disorders, so I’m relatively convinced that that form of GABA is active in the central nervous system and is probably crossing the blood-brain barrier. Other forms of GABA prior to using Kavinace I didn’t have much success with, so that’s been my experience so far.