A dentist’s insight: fermented lingonberry juice supports oral health
Lingonberries—those tart, ruby-red berries most widely found in Northern forests—are more than just a tasty treat. They are also found to offer surprising relief for oral health problems.
Pirjo Pärnänen, a dentist and researcher at the University of Helsinki, thinks back to when the idea of harnessing lingonberries for oral health first took shape. It was inspired by a traditional remedy and a lingering question: could science confirm the healing power of this humble berry?
“It began with a patient,” Pärnänen recalls. “While working as a dentist, I noticed that individuals using asthma medication or struggling with blood sugar regulation often developed yeast infections, which then progressed to oral thrush,” she explains.
Lingonberries are small, tart berries native to boreal forests and Arctic tundra as well as high-lying areas elsewhere throughout the Northern Hemisphere – especially in Fennoscandia and parts of North America. These berries grow on low evergreen shrubs and are closely related to cranberries.
Rich in antioxidants, vitamins C and E, and beneficial plant compounds, lingonberries have long been valued for their health-promoting properties. While lingonberry is perhaps the best-known English name for the plant, it is also known by many other names, such as cowberry or mountain cranberry. The scientific name is Vaccinium vitis-idaea.
From folk remedy to scientific discovery
Lingonberries have been used in folk medicine for generations to treat various health ailments, including mouth thrush and stomach discomfort. Traditional remedies often involved lingonberry juice or extracts, due to their antibacterial and anti-inflammatory effects, Dr. Pärnänen says.
“In the past, health clinics advised placing lingonberries on a child’s tongue to treat thrush caused by yeast. I wondered if there could be a scientific basis for this folk remedy. “
In 2007, Pärnänen launched her first scientific studies. She compared different wild berries – bilberry, cranberry, strawberry, and wild blackcurrant – and found that lingonberry stood out.
“Lingonberries contain more of certain phenolic compounds than other berries. This makes them exceptionally powerful,” she explains.
The first clinical trials with unprocessed lingonberry juice were unsuccessful, she admits, but her search for a perfect remedy continued.
“The sugars in lingonberry juice feed yeasts. The solution was found in fermentation—when the sugars were removed, the effects on oral health became positive.”
Fermented lingonberry juice inhibits the growth of yeasts and bacteria that cause tooth decay. Studies show that it may even slow down the proliferation of cells associated with oral cancer.
“Polyphenols, which are beneficial for oral health, are preserved after fermentation, but without sugar. This means that the product does not damage tooth enamel or feed harmful microbes,” says Pärnänen.
An aid for gum disease and dry mouth
Dry mouth is a common oral health problem, especially among the elderly and those taking multiple medications. According to Pärnänen, it is often an underestimated condition.
“According to estimates, up to a third of adults suffer from dry mouth, and the prevalence among older generations may be even higher. A lack of saliva is not just an unpleasant sensation—it also increases the risk of tooth decay, gum disease, yeast infections, and other mucosal damage,” Dr. Pärnänen says.
According to the World Health Organisation (WHO), more than 3.5 billion people suffer from oral diseases, and the prevalence of severe gum disease, periodontitis, has nearly doubled between 1990 and 2019.
In clinical trials, the fermented lingonberry mouthrinse developed by Pärnänen has been proven to relieve dry mouth and gum disease as well as curb yeast infections.
“Natural ingredients have sometimes been considered nonsense, but folk traditions do not arise out of thin air. The forest has always been our pharmacy,” the Finnish researcher says.
From nature to a clinical product
Following years of research, Dr. Pirjo Pärnänen’s fermented lingonberry solution was officially granted Class 1 medical device status. Today, the product—marketed as Lingora®—is available in Finnish pharmacies and online.
“Acute yeast infections still require medication, but Lingora ® offers excellent support for self-care,” Pärnänen explains.
Using it is simple: “Swish the solution in your mouth for 30 seconds and spit it out. A two-week course, twice daily, is effective. For longer-term use, once a day is enough,” she advises.
This all-natural remedy has already sparked international interest and is now available in several countries, including in the UK.
“Germany has a long tradition of natural medicine,” Pärnänen notes. “Lingonberries aren’t as well-known there as cranberries, which opens exciting opportunities for Finnish research and health innovations.”
For Dr. Pirjo Pärnänen, lingonberry research is just the beginning. “Bilberries, cranberries, and other wild berries contain compounds that can benefit eye health, metabolism, and more. The potential for research is nearly limitless,” she says.
Pärnänen encourages young scientists to explore this fertile field. “It’s vital for forestry and medical professionals to find common ground. Research and product development demand perseverance, resources, and courage. Yet Finnish investors remain cautious, despite the enormous potential. If we don’t invest in our own innovations, someone else will.”
Her personal mission is clear.
“I want to develop safe, effective natural products that support oral health. Wild berries are packed with bioactive compounds that can’t even be synthesized. They deserve a place in medicine—not just as food, but as part of treatment.”
Pärnänen’s work with lingonberries continues to evolve. “There’s still much to uncover about the effects of fermented lingonberry juice. We currently have three follow-up studies underway, and the results look promising. The product range may grow—Lingora® mouthrinse is just the beginning.”
