Cranberry juice may be a boon for oral hygiene

Boil them, mash them, simmer them in a sauce.

Whether they're sweetening a salad, garnishing a cocktail or brightening up home décor, cranberries are an iconic ingredient in holiday festivities. UIC College of Dentistry researcher Christine Wu found another reason to add these tart treats to your grocery cart: oral health.

Medicinally speaking, cranberry juice is often used to ward off urinary tract infections. That's because the crimson berries contain anti-inflammatory compounds called proanthocyanidins that unstick bacteria, like E. coli, from cells.

Wu wanted to see how the proanthocyanidins in cranberries affect dental plaque bacteria, which use sugars to produce acids that cause enamel decay. Since people don't typically snack on chemical compounds, she presented them as a more palatable refreshment: pure cranberry juice.

"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.

In her study, 14 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.

On the morning of the study, participants arrived with a night's worth of plaque buildup on their pearly whites. With cotton swabs, researchers collected plaque samples from one side of their mouths. The participants rinsed with water before consuming three small drafts of their assigned beverage, swishing a few times before swallowing.

Thirty minutes later, the researchers collected plaque samples from the participants' unswabbed teeth. They'd assess the beverages' effects on these samples compared to those collected before the experiment.

Sure enough, the plaque exposed to pure cranberry juice appeared to be growing more slowly than the unexposed samples. Swishing with pure cranberry juice was also linked to less acid production in both adults and children - a key factor for healthy enamel.

Wu said she's excited for the potential of cranberry juice be considered a "function beverage" that benefits oral health, especially because other popular juices - like orange and apple - didn't fit the bill.

"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.

Due to the study's small sample size and short-term testing period, additional experiments are needed to validate these results, Wu said. In the meantime, Wu is open to the occasional pure cranberry juice mouth cleanser.

"But maybe by adding an appropriate sugar substitute," she said, "to make it a bit more palatable."

This research appears in the journal Scientific Reports.