I've been taking between 1000-1200 mg daily of mostly alpha gpc, but also experimenting with throwing in some cdp choline as well, for the past 2-3 weeks. Also eating 2 eggs on most of those day. I will probably also continue to add more supplemental choline. I gotta say, the initial results are promising.
Others have already pointed out that symptoms of choline deficiency and acetylcholine issues seem to perfectly match our symptoms. I seem to have problems during POIS with everything the vagus nerve is connected to: eyes, voice, lungs, digestion, muscle tightness, short term memory and recalling words. Even chronic recurring constipation and very high eye sensitivity to light outside of POIS.... Both things that are controlled by the vagus nerve. I even posted a while ago that a sleep tracking app showed I was completely skipping over REM sleep while in POIS, and acetylcholine is needed for REM sleep.
The biggest issue for me was complete lack of control over anxious feelings while in POIS, and these anxious feelings would often spin out of control to near panic, accompanied by a constant elevated heartbeat and inability to focus on anything. I'm no medical expert but that sure seems like a parasympathetic nervous system that is not able to function properly. And what does your parasympathetic nervous system need to function properly? Choline.
The fact that I can take such high daily doses of choline supplements while a lot of people say that even small doses of choline supplements sends them into deep negative side effects says to me that maybe my body is starved of choline.
I sure hope works because I'm at the end of my rope here...