I washed out after six years of biochem doctoral ed, and worked in biotech, so I pretend like I understand how all this stuff works. Of course I don't, and there's all kinds of weird pathways still being discovered. So don't let my tirades be a substitute for your own research or, for things that are mostly harmless, personal anecdote. Of course, if you do find new research, point it out to me.
Caffeine blocks adenosine receptors in your brain. Adenosine slowly builds up while you're awake, and gets cleared away while you sleep. Going cold turkey on caffeine would make your brain think it hadn't gotten enough sleep, making you cranky. Thinks like headaches might be from vasodilation--caffeine gets added to drugs like Excedrin because it helps constrict blood vessels. So I don't think there's any reason to think dopamine is that involved with caffeine withdrawal. Maybe with addiction to it, but addiction has nothing to do with the sorts of dopamine depletion that meth users worry about, just dopamine signalling.
And, there's no reason to believe eating dopamine precursors increases dopamine signalling. If it did, eating a steak would give you a rush like meth. L-Dopa, a medication for Parkinson's disease, can increase dopamine reserves, but it's prescription-only* for that reason. And that's in people who have a dopamine disease. 5-HTP, the serotonin precursor beloved by MDMA users, has been shown to do nothing for your serotonin signalling, and may make depression worse by forcing a downshift in dopamine production.
So I'm positive phenylalanine (and tyrosine) supplements have no benefit for meth users, and pretty sure it wouldn't help caffeine withdrawal. But, supplements are cheap and generally safe, there's no reason not to try it out.
*You can find L-Dopa supplements, but if you notice, it's extract from some plant that is high in natural L-Dopa. If it was rich in L-Dopa enough to have effects, it wouldn't be sold OTC because the side effects would start class-action suits. Plus it wouldn't make your meth high any better anyway.
This is the link that made me think Phenylalanine can help with caffeine withdrawal.
If you could please read it and let me know if there's any logic to what this guy is saying and if not, why he'd even say this at all if it's not true, I'd appreciate it:
https://johnfawkes.com/how-to-cure-a-caffeine-addiction-in-four-days-without-withdrawal-symptoms/
As you can see, he says that caffeine causes deficiencies in Phenylalanine and L-Tyrosine and that therefore taking them can fix them and help you get over caffeine WD.
Is that true and if not, why not?
Also, can you think of any other type of supplement or drug that COULD help with caffeine withdrawal (not the headaches, I can take care of that with Aleve, but with the physical exhaustion and to a lesser extent, depression)??
I know it seems funny using a much stronger stimulant to come off a weaker one, but back when I DID have access to dexadrine (which I don't anymore) it helped me get of caffeine (then I stopped the Dex too).
I guess it makes sense a stimluant could help with stimulant WD.
I'd just like anything that could make it easier.
Thanks