(man this board is slooooow, now I remember one of the reasons I left

)
The CIO thread sort of went off on an interesting tangent and I thought it might make a good discussion... Maybe I'm just really stupid on this topic (or uninformed might be a better word).
I thought the jury was OUT on how impactful the mother's diet was to a breastfed baby. I've read experts who say that the impact is WAY overstated and that mothers should not have to modify their diets in any way. That women in other countries don't do any diet modification and all that.
Then again, I've also read about the elimination diet (when babies are fussy) and that foods that cause allergies should be avoided and all that too.
Is there ANY scientific proof or evidence that one or the other of these is correct?
One of my concerns is this-- we (collectively, 'cause I sure did it too) are so quick to blame our milk supply. I think this - for some people - causes a premature ending of a nursing relationship because a mother is blaming her breastmilk for the fussiness or eczema or whatever and so she reaches, in desparation, for formula thinking it might solve the problem. When it doesn't, there is generally no turning back.
Are we SURE that what we eat has an impact? Is that PROVEN? If it's not proven, then are we propegating information that is harmful to the advocacy of breastfeeding?
I truly don't know the answers. But if there is no proof, then I'd hate to continue to propegate false information (unless the lack of proof is simply for lack of the whole topic having been studied, then I suppose the 'answer' is up in the air).
Does your mother-instinct tell you that your diet absolutely has an impact on the baby's behavior?