Hi, not sure why you'd use white vinegar, to 'seed' the kombucha -- the only thing I ever think of it for, is maybe washing windows. :-) Ah, but I just remembered, Susun Weed, of the Wise Woman herbal tradition, suggests using it to make her loaded mineral vinegars--(mainly to save money, I think). And the sense here is, there are plenty enough minerals in the herb used to outweigh any 'badness' in the white vinegar.** Just personally, I find the thought of it rough, on the poor SCOBY. That alone might bother you. If ever I do not have some K-Tea to add to a new batch I'm making, I might use a little real acv. Just a touch.
Thes days, if I was stuck starting over--and I was, recently, I got a bottle of good kombucha, from the 'healthier foods store', and added my green tea and cane Sugar
to it. And voila--a brand new scoby. Took about 14 days. I use about a cup of organic cane Sugar
to 3 quarts
If you 'OD' on it, and one cup might have been an OD, depending on your current inner flora state, then yes, you could get a bad headache--esp. if elimination is in any way backed up. If you are not having a BM for every meal eaten, then elimination IS backed up. Additionally, the state of your liver has a big bearing on how a cup of kombucha might affect you..
** thinking a bit more on this white vinegar thing-...in the case of the mineral vinegars (her "Old Sourpuss" is a good menopausal formula, for women to make/take ), I do see the reasoning of not introducing the 'mother', in that perhaps it might complicate the mineral extraction. I tend to be someone who likes to err on the side of Natural though, and take my chances, with the final brew.