Hi Kathleen and others
I actually really don't know. My daughter is a lifelong veggie (now vegan), and it's all a bit strange as me and her dad are meat eaters, but from weaning onwards she just wouldn't touch stuff that wasn't mainly plant-based. Two things I've noticed (purely anecdotal): since she moved back home a couple of years ago, we've all pretty much been following the same diet (high protein plant-based), and we're generally more chipper. It seems to take care of some issues, such as bloating, sluggishness, upsydownsy moods - not entirely, but we've noticed an improvement; on the other hand, said daughter has PMDD (diagnosed by the GP) and we're not sure of dietary effect because she's always been veggie (and vegan for the last 10 years or something) and so we haven't got anything to measure the symptoms against, if that makes sense. She might be worse (god knows what that would look like) if she was a meat eater, there's no telling.
My wild assumption about all of this is that if you get a good baseline health (less carbs, reduction in refined sugar, watch your caffeine intake, etc), then you're more likely to be able to withstand the slings and arrows of outrageous fortune (hormones). I believe (with no evidence whatsoever) that this is probably easier to achieve if you're eating 'consciously' - which (from experience) it would seem most vegans do as they're constantly having to think about how they're going to source the right food, get all the nutrients needed, find the time to cook, etc. It makes a slack sense to me that the body would respond according to the fuel it's provided.
I would also say though that I casually subscribe to the blood group eating diet idea - partly because it was the only thing that really explained why kiddo wouldn't touch meat (she's A type). Happy to admit this might be total hippy tosh. Don't much care.