In a small human study, unsweetened pure cranberry juice was linked to slower plaque regrowth and lower acid production, hinting at a possible oral health benefit.
Cranberry juice has a reputation for being tart, acidic, and often sugary, qualities that might seem poorly suited to protecting teeth. A small human study from the University of Illinois Chicago, however, found that unsweetened pure cranberry juice was associated with slower dental plaque regrowth and lower acid production.
UIC College of Dentistry researcher Christine Wu examined whether compounds naturally found in cranberries could affect dental plaque bacteria, which feed on sugars and produce acids that contribute to enamel decay. Cranberries contain proanthocyanidins, anti-inflammatory compounds known for their ability to interfere with the attachment of bacteria such as E. coli to cells.
“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,” Wu said.
Testing pure juice against sweetened cranberry drinks
Rather than testing isolated cranberry compounds in the laboratory, Wu and her colleagues used commercially available beverages. Fourteen children and eight adults were randomly assigned to drink either unsweetened pure 100% cranberry juice, a cranberry juice cocktail containing 27% juice with added sugar, or water.
“It was important to us to conduct these tests with human participants and use products available on the market. Most cranberry juice studies have been conducted using laboratory-prepared cranberry juice extract. Moreover, limited studies have been performed in children,” said Wu, who is a professor of pediatric dentistry.
Participants arrived on the morning of the study with plaque that had accumulated overnight. Researchers first used cotton swabs to collect plaque samples from one side of each participant’s mouth. After rinsing with water, participants drank three small portions of their assigned beverage, swishing each several times before swallowing.
Thirty minutes later, researchers collected plaque from teeth that had not been swabbed earlier. This allowed them to compare plaque collected before and after exposure to the beverages.
Cranberry juice reduces plaque acid production
Plaque exposed to pure cranberry juice appeared to regrow more slowly than the samples collected before the experiment. Swishing with pure cranberry juice was also associated with lower acid production in both children and adults. That matters because acids produced by plaque bacteria can contribute to the breakdown of tooth enamel.
The findings raised the possibility that cranberry juice could eventually be considered a “functional beverage” with potential oral health benefits. Wu noted that other commonly consumed juices, including orange and apple juice, had not shown the same promise in her work.
“Most people think of cranberry juice as very sour, very acidic and sugary, and therefore may not contribute positively to oral health. This study found the opposite: that cranberry juice affected dental plaque regrowth and acid production, which may counteract some of the damage done by sugar,” she said.
Promising results need larger tests
The results are preliminary. The study included only 22 participants and measured short-term effects, so additional experiments will be needed to determine whether the findings hold up in larger groups and over longer periods.
For now, Wu said she would not rule out occasionally using pure cranberry juice as a mouth cleanser.
“But maybe by adding an appropriate sugar substitute,” she said, “to make it a bit more palatable.”
Reference: “In vivo exposure to cranberry juice suppresses dental plaque regrowth and acid production in adults and children: a PGRM study” by Christine D. Wu, Wei Li, Monique Luu, Evelina Kratunova and Qian Xie, 23 June 2026, Scientific Reports.
DOI: 10.1038/s41598-026-56025-3
This research was partially supported by the Department of Pediatric Dentistry, College of Dentistry, University of Illinois Chicago.
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