Yeah, I just actually read the thing after ctrl f-ing for citric acid.

( Mu Dinofiddler, Tue 19 May 2009, 14:19, archived)

I think it's trying to slate non-cola fizzy drinks -
sprite and that kind of thing that don't contain phosphoric acid but do have citric acid added as a flavour enhancer - for being bad for teeth. I don't think it's suggesting natural fruit juices are bad for teeth. But they've got confused with the scientific reasoning behind the actual results and applied their own primary school chemistry logic
( the mighty badger Aphrodite, on a bar stool, by your side, Tue 19 May 2009, 14:28, archived)