Added sugar in raisin bran cereals increases acid in dental plaque, leading to tooth decay, a new study has shown.
During the study, research team from University of Illinois at Chicago compared four food groups - raisins, bran flakes, commercially marketed raisin bran cereal, and a mix of bran flakes with raisins lacking any added sugar in children aged 7 to 11.
Sucrose, or table sugar, and sorbitol, a sugar substitute often used in diet foods, were also tested as controls.
They found that all test foods except the sorbitol solution promoted acid production in dental plaque over 30 minutes, with the largest production between 10 to 15 minutes.
Eating commercially marketed raisin bran led to significantly more acid in the plaque.
Lead researcher Christine Wu said there is a "well-documented" danger zone of dental plaque acidity that puts a tooth's enamel at risk for mineral loss that may lead to cavities.
Achint Utreja, a research scientist and dentist formerly on Wu's team, said plaque acidity did not reach that point after children consumed 10 grams of raisins.
Adding unsweetened raisins to bran flakes also did not increase plaque acid compared to bran flakes alone.
Plaque bacteria on tooth surfaces can ferment various sugars such as glucose, fructose or sucrose and produce acids that may promote decay.
The study is published in the journal Pediatric Dentistry.