Simple sugars like sucrose, fructose, lactose, galactose, and glucose foster colonisation and growth of bacteria linked to caries, particularly Streptococcus mutans.2 Studies indicate that subjects placed on high-sucrose diets exhibit increased S. mutans counts and the incidence of early carious lesions. Although starch is recognised to have a lower carcinogenicity than sucrose, frequent consumption of starch has been shown to produce a large number of carious lesions. This is because starch can be broken down to maltose by the enzyme in saliva called amylase. Maltose can then be further metabolised to acids, which in turn lead to demineralisation.3
Conversely, dietary restriction of fermentable carbohydrates and cooked starches reduce the level of cariogenic organisms in humans. A classic 15-year intervention study, the Hopewood House Study conducted in Australia,4 evaluated the clinical effects of a sucrose-restricted diet among 81 children, aged 4 to 9 years. At the start of the study, 78% of the children were caries-free, and 53% continued to be caries-free at age 13. This was significantly higher than the proportion of caries-free 13-year-olds within the general residential population—only 0.4%. When the children from Hopewood House were relocated as they became older, they no longer adhered to their strict diet. The result was a steep increase in caries increment, similar to that found in other children, indicating that teeth do not acquire any permanent resistance to dental caries.
Figure 1. The number of decayed, missing or filled (DMF) teeth with caries in the general population compared to children in Hopewood House.