A staple of the Western diet, milk is the beverage that best protects teeth from decay while eating sugary foods such as breakfast cereals.

Cow's milk performed better than tap water or apple juice in preventing bacteria feeding on the sugar from producing acids that cause tooth decay. In a small study in Chicago, researchers gave 20 volunteers each a bowl of sugary cereal, which they ate before drinking small glasses of milk, water, or apple juice.

Like children watching Saturday morning cartoons, the study participants — all of them adults — ate the sugary snack before downing the beverages, after which researchers measured levels of acid on their teeth.

Greater levels of acid produced by bacteria feasting on sugar indicates greater likelihood of tooth rot over time. However, milk was found to counteract the acidic build up.

"Eating dairy products in combination with other sugary snacks or at the end of a meal may be an effective means of caries prevention," the researchers told media. By stopping the bacteria from producing acid, the beverages protect teeth from future decay.

After consuming the cereal, acid levels in the mouth rose among all study participants — but was quickly squelched by the protective properties of milk. The researchers also measured the effects of water and apple juice on mouth acid levels after consumption of the sugary cereal, finding that milk performed best and apple juice the worst.

In addition to lowering acid levels in the mouth, milk may help strengthen teeth weakened by acid, the researchers concluded in a paper published in the Journal of the American Dental Association.

Conversely, apple juice and other fruit and fruit-based juices may contribute to dental decay, Nigel Carter, of the British Dental Health Foundation, told media. Carter and other dental health experts advise parents to avoid feeding their children either sugary cereals or fruit juices, adding that children and adults alike would benefit from avoiding such snacks.

While acid levels in the mouth fall between meals, more frequent snacking may keep them elevated and thus increase the chances of dental decay over time. "Chocolate, biscuits, cakes, dried fruit, soft and fizzy drinks, along with squashes, are all high in sugar, which can lead to decay or damage tooth enamel."

An earlier study in 2008, however, found a greater likelihood of tooth decay among children who consumed more soft drinks and less milk and fruit juice — though the researchers made the distinction between 100 percent fruit juice and other fruit juices with added sugar. In that longitudinal study, researchers followed 369 African American children ages 3-5 in Detroit, studying the causes of tooth decay among low-income populations.

Researchers in that study advised parents to avoid giving their children soft drinks, but made no recommendations about milk.

Source: Naval, Shilpa, Koerber, Ann. The Effects Of Beverages On Plaque Acidogenicity After A Sugary Challenge. JADA. 2013.

Source: Lim, Sungwoo, Sohn, Woosung, Burt, Brian A., Sandretto, Anita M., Koker, Justine L., Marshall, Teresa A., et al. Cariogenicity Of Soft Drinks, Milk And Fruit Juice In Low-Income African American Children. JADA. 2013.