Pretty tough to preserve wine without sulfites, which is why most wineries don't bother. You need to nuke it in order for it to not ferment again.I was talking Sunday to a winemaker that said shipping wine without sulfates (natural wine?) can be sketchy so he doesn't make it. He said something like temp variations can increase volatile acidity and make it smell/taste like vinegar. Makes total sense if it stays close to home like those wineries in Italy that. But look on the back of the same bottle you buy in USA and it probably says "contains sulfites". (grapedrink to the courtesy phone)
As for what causes headaches more with US made wines, I think it's histamines. Grapes are picked at a higher sugar level and are extracted more in the winery, which likely leads to more histamines. There are also several dozen additives that are allowed under federal allow that are not required to be labeled. Who knows what kind of synergies there are when you combine histamines, additives, high alcohol, etc, especially as it pertains to food sensitivities and allergies at the individual level.