By definition, a carbonated beverage is a liquid that has had carbon dioxide gas dissolved into it. This gas produces the fizzy bubbles that have made such beverages so wildly popular.
Yet, a side effect of forcing carbon dioxide gas into a beverage is that some of the carbon dioxide will react with water to form carbonic acid. This acid is responsible for the characteristic "bite" of most sodas, and its absence is part of the reason that flat sodas taste so different.
In addition to the naturally occurring carbonic acid, colas including Coca-Cola and Pepsi Cola are made with added phosphoric acid.
No matter how low the concentration, it's not a good idea to drink acidic beverages too frequently. Of people who drink carbonated beverages regularly, this acid gradually wears down the enamel of their teeth and leave them vulnerable to tooth decay.
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