There is a synergy in the sense that it is my understanding that b5 assists inferior choline sources like bitartrate in crossing the blood brain barrier (Choline's quaternary amine renders it lipid insoluble which might suggest it would be unable to cross the blood-brain barrier).
If you are serious about boosting acetylcholine I would consider switching to CDP Choline or Alpha GPC (preferably the former since there has been significantly more studies does on it, showing its effectiveness), as they are superior sources of choline when compared with Choline Bitartrate, whose bioavailability is low.
By the way, Lecithin is a better source of choline than than bitartrate, as it contains phosphatidylcholine, has all the beneficial effects of choline bitartrate, but is both more bioavailable and less expensive.
Centrophenoxine is the holy grail of acetylcholine IMO.
Edited by hamishm00, 23 September 2009 - 02:50 PM.