Sugar may rot your teeth, but the acid in energy and sports drinks will also do some irreversible damage to those (not so) pearly whites, say researchers.

A new study published in the journal General Dentistry found that energy and sports drinks contain so much acid that they start destroying teeth after only five days of consistent use. Thirty to 50 percent of American teens use energy drinks, the paper says, and up to 62 percent drink sports drinks at least once a day.

Damage to enamel can cause teeth to become sensitive to touch and temperature changes, and be more susceptible to cavities and decay.

"Young adults consume these drinks assuming that they will improve their sports performance and energy levels and that they are 'better' for them than soda," said Poonam Jain, lead author of the study. "Most of these patients are shocked to learn that these drinks are essentially bathing their teeth with acid."

Jain and colleagues analyzed the titratable acidity, pH and fluoride of 13 different sports drinks and nine energy drinks (including Gatorade and Red Bull) by submerging samples of human tooth enamel in each beverage for 15 minutes. They then immersed the samples in artificial saliva for two hours. This was repeated four times a day for five days. The scientists observed damage to the enamel by the time the five days were up.

Energy drinks were the worst culprits, the researchers said. They said acidity levels vary among brands and flavors of energy drinks, and caused twice as much damage as the sports drinks.

"Bacteria convert sugar to acid, and it's the acid bath that damages enamel, not the sugar directly," said Dr. David Katz, director of the Yale Prevention Center. "So by incorporating a high acid load in a drink, we are just cutting out the middleman on the way to tooth decay."

These drinks are glorified sodas, with as much or more sugar, said Katz.

The American Beverage Association took up arms against the study, noting in a statement that people do not keep any kind of liquid in their mouths for 15 minute intervals over five-day periods.

"Thus, the findings of this paper simply cannot be applied to real life situations," the statement read. "Furthermore, it is irresponsible to blame foods, beverages or any other single factor for enamel loss and tooth decay (dental caries or cavities).  Science tells us that individual susceptibility to both dental cavities and tooth erosion varies depending on a person's dental hygiene behavior, lifestyle, total diet and genetic make-up."

Nevertheless, while Katz said there may be a role for sports drinks for rehydration among endurance athletes under intense training conditions, they make little sense for anyone else.

"A far better approach would be working to improve sleep quality and quantity and overall health," said Katz. "When these drinks combine a load of acid and sugar, they are detrimental to waistline and smile alike."