Nutrients in cranberries and blueberries could prevent tooth decay

A new study published in the European Journal of Oral Sciences suggests that a handful of dark-coloured berries may lower the risk of tooth decay.

Scientists have found that nutrients in cranberries and blueberries can be highly effective in protecting the teeth against a strand of bacteria responsible for accelerating tooth decay.

Dark-coloured fruit berries are a rich source of polyphenols that could provide innovative bioactive molecules as natural weapons against dental caries.

The study (Philip et al, 2018) supports previous research by suggesting these are good for oral health by preventing ‘bad bacteria’ from sticking to the teeth and gums.

This could help reduce tooth decay, plaque and gum disease.

High-quality extracts of cranberry, blueberry, and strawberry, and a combination of the three berry extracts (Orophenol), were used to treat 24-h-old Streptococcus mutans biofilms. The grown biofilms were treated with the berry extracts and treated biofilms were assessed for metabolic activity, acidogenicity, biovolumes, structural organisation, and bacterial viability.

The biofilms treated with the cranberry and Orophenol extracts exhibited the most significant reductions in metabolic activity, acid production, and bacterial/exopolysaccharide (EPS) biovolumes, while their structural architecture appeared less compact than the control-treated biofilms.

The blueberry extract produced significant reductions in metabolic activity and acidogenicity only at the highest concentration tested, without significantly affecting bacterial/EPS biovolumes or biofilm architecture.

The results indicate that cranberry extract was the most effective extract in disrupting S. mutans virulence properties without significantly affecting bacterial viability. This suggests a potential ecological role for cranberry phenols as non-bactericidal agents capable of modulating pathogenicity of cariogenic biofilms.

Chief executive of the Oral Health Foundation, Dr Nigel Carter OBE, believes polyphenols could eventually lead to new oral care products.

‘The nutrients and fibre in fruit are vital for our health and wellbeing,’ he said.

‘Cranberries seem especially good for our oral health, as their polyphenols stick around in our saliva and will continue to help our mouth, even after we’ve swallowed them.’

‘What is especially exciting is that these natural extracts are completely sugar-free. This means they can be added to oral care products in several ways.

“They can dissolve in water so can be used to create healthy drinks, as well as to reformulate unhealthy drinks packed full of sugar.

“They also have wider applications for tooth decay prevention and control.  Mouthwash could benefit from this ingredient, as could toothpastes. More testing must be done but it will be extremely interesting to see whether manufactures make more use of polyphenols in the future.”

Dark-coloured berries are among the best dietary source of antioxidants. They provide a good supply of water and fibre, as well as other nutrients.

However, along with other fruit, they may also contain high amounts of natural sugar.

The recommended daily allowance of sugar for an adult is 90 grams or 22.5 teaspoons per day. This includes 60 grams of natural sugar and 30 grams of added sugar.

One portion of cranberries contains up to four grams of natural sugar (equivalent to one teaspoon) while a serving of blueberries is nearly 10g.


Philip, N., Bandara, H., Leishman, S. and Walsh, L, ‘Inhibitory effects of fruit berry extracts on Streptococcus mutans biofilms,’ European Journal of Oral Sciences. 2018. doi: 10.1111/eos.12602.


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