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Food contains different types of starchy carbohydrates with diverse degrees of processing. Processed forms of starch increases the risk of cavities because they can be broken down into sugars in the mouth, by amylase in saliva. Consuming whole grain starches lowers the risk of oral cancer.
The findings come from a review of the 33 academic papers on starch and oral health. According to Paula Moynihan, Professor of Nutrition and Oral Health at Newcastle University, UK, who lead the research, the evidence suggests that a diet rich in whole grain carbohydrates is less likely to damage oral health than food containing processed starches.
In the review, 33 papers were included of studies on foods containing what were characterized as rapidly digestible starches like white bread, crackers, biscuits, cakes, pretzels and slowly digestible starches like wholegrains, legumes and their relationships with dental caries, oral cancer and gum disease.
The World Health Organisation (WHO) is currently updating its guidance on carbohydrate intake including assessment of dietary fibre and starch quality. WHO recommends reducing free sugar intake to less than 10 % of total calorie intake, and suggests further reduction to less than 5% for additional health benefits.
Free sugars are sugars that are added to foods by the manufacturer, cook, or consumer, plus those naturally present in honey, syrups, fruit juices and fruit juice concentrates. Carbohydrate-rich diet is shown to be fine for oral health as long as it is low in sugars and is based on whole grain varieties.