Cranberries' protective properties may help thwart tooth decay and cavities, according to the findings of a study reported in Caries Research (January 2006). The study involved coating a synthetic material that acts like tooth enamel (hydroxyapatite) with cranberry juice. The researchers then applied the cavity-causing bacteria Streptococcus mutans, plaque, or glucan—a type of enzyme that builds plaque. After 7 months, the results showed that cranberries were about 80% effective in protecting teeth, said Hyun Koo, DDS, MS, PhD.

Dr. Koo warned against individuals drinking or eating large amounts of cranberry-containing products because of the sugar added by the food industry. He said that more laboratory tests are necessary.