okay, although i can find this:
With multiple sclerosis, this problem may be caused by interruption of brain impulses that control that part of the urination process...
it also would seem that the mainstream dietary recommendations are to avoid coffee, alcohol, orange juice
mainstream meds are antispasticity drugs
this suggests mineral issues moreso than vitamin issues to me.
link to abstract (oral magnesium therapy combats spasticity in ms)
link to abstract (low magnesium, copper, zinc in ms)
so. the mainstream recommendations do seem to tie in nicely, since it's well researched that coffee and alcohol suck magnesium out of you (i don't know anything about the evils of orange juice so far)
i advise you to try the mg bandwagon and get yourself some of that natural calm stuff and take the usual dose at bedtime. i think it's 600mg, cheer knows. i just take pills at random times but i do know you're supposed to have it between meals. mg has helped me a lot with my spasticity issues.
just for general urinary health, maybe try cranberry juice in between beers too. or perhaps you could invent an exciting new cran-beery cooler