When I first started watching my calories, I mentioned changing from regular soda to diet soda. Some folks immediately chided me that such stuff was Tooth Decay on Wheels. “It’s a lot more acidic than regular soda — it’ll rot your teeth right out.”
I finally got around to googling on the subject, and, despite that claim being echoed in text at various sites (many of which are flogging their own Health Water, ahem), the only actual figures I found indicated that diet soda is less acidic than regular pop — and, lacking sugar, is less conducive to cavity-creating bacteria.
I was able to find a few sites with info on pH levels of sodas. Recalling that low pH is more acidic (battery acid is 1.0, water is 7.0), here are some comparisons (regular vs diet): Coke (2.6 vs 3.4), Doctor Pepper (2.9 vs 3.4), Pepsi (2.5 vs 3.1), Mountain Dew (3.2 vs 3.3), Barq’s (4.6 vs 4.6).
In nearly all the the cases, the “real” soda has a more acidic pH than the diet version.
Diet sodas get a lot of attention on their acid content because, well, they don’t have sugar, and that’s the obvious thing to talk about with regular sodas. (Indeed, it’s a lot harder to find pH for regular soda, except for vague warnings of the diabolical nature of Coke).
All of which is not to say that diet soda is particularly good for you, or that the acids there are to be sneezed at. You should still brush your teeth, or flush your mouth out with water (or both) after a can of Diet Coke. All soda is acidic.
But the idea that diet soda is more acidic than its sugary counterpart seems to be — well, just plain wrong.
Actually, the last dental bulletin I read said you wanted to wait 30 minutes or so to brush after you drank a soda so as not to push the material back into your teeth. [shrug] YMMV.
At least one site I saw noted that brushing while you have a mouth full of soda will further abrade the teeth, and suggested washing your mouth out with water first (or, at a minimum, instead).
That’s why I usually go heavy ice with my drinks.