Study examines effect of cranberry juice on dental plaque

Dental Tribune International

Wed. 28. October 2026

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CHICAGO, US: Foods and beverages are attracting increasing research interest for their potential effects on oral biofilms. In two randomised controlled trials, researchers have investigated whether unsweetened cranberry juice can reduce bacterial growth and acid production in plaque from adults and children. The findings suggest that cranberry juice may influence plaque metabolism and could inform further research into dietary approaches to caries prevention.

Prof. Christine D. Wu is investigating how beverages such as cranberry juice may influence bacterial activity in dental plaque and potentially contribute to caries prevention. (Image: University of Illinois Chicago)

“Just like sugar damage is linked to diet, I’m interested in how the food and beverages we consume can help combat the harmful bacteria and benefit our oral health,” lead author Dr Christine D. Wu, professor of paediatric dentistry in the University of Illinois Chicago College of Dentistry, said in a university press release. She explained that most studies on cranberry juice to date have used laboratory-prepared cranberry extract rather than commercially available juice and that few have been conducted in children.

In the study, the researchers conducted two randomised crossover trials involving eight adults and 14 children. At separate visits, participants rinsed their mouths with and swallowed one of three beverages: water (the control), unsweetened 100% cranberry juice or a cranberry juice cocktail containing 27% juice and added sugar. The researchers collected plaque from one side of each participant’s mouth before exposure and from the opposite side 30 minutes afterwards. They then tested the samples in the laboratory to assess subsequent bacterial growth and acid production.

After exposure to the unsweetened cranberry juice, plaque samples showed reduced bacterial growth and acid production in laboratory tests compared with samples collected before exposure. Bacterial growth fell by almost half on average in adults and by about one-third in children, and acid production was also reduced in both groups. By contrast, neither the cranberry juice cocktail nor water produced statistically significant inhibitory effects.

The findings suggest that unsweetened cranberry juice may temporarily suppress bacterial growth and acid production in plaque. They also support the potential use of the method employed to test the plaque samples for assessing the antiplaque effects of other foods and beverages.

Dental Tribune International has previously reported on several studies investigating the effects of natural substances and beverages on oral biofilms. For example, one study found that a maple-derived compound inhibited Streptococcus mutans biofilm formation in laboratory experiments. Another study compared the effects of bovine milk and oat, almond and soy drinks and found that bovine milk and soy drinks reduced cariogenic biofilm activity, whereas bovine milk and oat drinks reduced periodontal biofilm activity. A recent clinical study also found that arginine, a naturally occurring amino acid, may reduce plaque acidity and alter biofilm composition.

The study, titled “In vivo exposure to cranberry juice suppresses dental plaque regrowth and acid production in adults and children: A PGRM study”, was published online on 23 June 2026 in Scientific Reports.