A reappraisal of the quantitative relationship between sugar intake and dental caries: the need for new criteria for developing goals for sugar intake.

Background: There is a clear relation between sugars and caries. However, no analysis has yet been made of the lifetime burden of caries induced by sugar to see whether the WHO goal of 10% level is optimum and compatible with low levels of caries. The objective of this study was to re-examine the dose-response and quantitative relationship between sugar intake and the incidence of dental caries and to see whether the WHO goal for sugar intake of 10% of energy intake (E) is optimum for low levels of caries in children and adults.

Methods: Analyses focused on countries where sugar intakes changed because of wartime restrictions or as part of the nutritional transition. A re-analysis of the dose-response relation between dietary sugar and caries incidence in teeth with different levels of susceptibility to dental caries in nationally representative samples of Japanese children. The impact of fluoride on levels of caries was also assessed.

Results: Meticulous Japanese data on caries incidence in two types of teeth show robust log-linear relationships to sugar intakes from 0%E to 10%E sugar with a 10 fold increase in caries if caries is assessed over several years' exposure to sugar rather than only for the first year after tooth eruption. Adults aged 65 years and older living in water fluoridated areas where high proportions of people used fluoridated toothpastes, had nearly half of all tooth surfaces affected by caries. This more extensive burden of disease in adults does not occur if sugar intakes are limited to <3% energy intake.

Conclusions: There is a robust log-linear relationship of caries to sugar intakes from 0%E to 10%E sugar. A 10%E sugar intake induces a costly burden of caries. These findings imply that public health goals need to set sugar intakes ideally <3%E with <5%E as a pragmatic goal, even when fluoride is widely used. Adult as well as children's caries burdens should define the new criteria for developing goals for sugar intake.