Better ways to prevent obesity and tooth decay in early childhood

A range of materials promoting oral health for children.

Dr Narendar Manohar (Western Sydney University), Professor Andrew Hayen (University of Technology Sydney), Associate Professor Amit Arora (Western Sydney University)

At school entry age, around 40% of Australian children already have tooth decay and around a quarter are overweight or obese. Both these conditions have a significant negative impact on the children, their families, and the healthcare system. This also increases the risk of progression of these conditions into adulthood.

These are some of the findings from the Healthy Smiles Healthy Kids study, which has investigated infant and young children feeding patterns and their links with obesity and tooth decay in early childhood.

Our study analysed longitudinal data to look at the effects of infant feeding, dietary trajectories (patterns), and behavioural factors on obesity and tooth decay in early childhood.

A better understanding of the diet trajectories of healthy and unhealthy foods in early life and their impact on subsequent obesity and tooth decay will help guide prevention strategies.

Our research team synthesised global evidence on the link between obesity and tooth decay in young children. Our paper exploring children’s co-vulnerability to obesity and tooth decay, published in Obesity Reviews, found that children with overweight and obesity have a higher tooth decay experience compared to normal weight children.

Also, low levels of parental education and income were identified to be the common risk factors for childhood obesity and tooth decay.

Another article, entitled “Who is not adhering to Australian feeding recommendations?” published in Nutrients, examined longitudinal data from 934 infants in South Western Sydney who were introduced core and discretionary foods in the first year of life.

Twelve percent of infants received ‘core’ foods – i.e., nutrient-rich first foods that are essential to meet infant’s increasing nutritional and developmental needs – before 17 weeks of age.

This is very early and concerning as Australian guidelines recommend introduction of complementary foods at around six months of age.

We argue that health professionals need to continue to get the message across to the community on the benefits of breastfeeding. We must also provide extra support to women who are at risk of stopping breastfeeding early.

The current recommendations in Australia state that discretionary foods should be avoided in the first year of life.

However, we’ve found 95.3 percent of infants received ‘discretionary’ foods, those that are considered unhealthy, or lack a high nutritional value – before 52 weeks of age.

A family’s socio-economic status (SES) had a more profound effect on the timing of discretionary foods introduction. We found infants from low SES families were almost four times more likely to be introduced to discretionary foods early.

This is very concerning as this puts infants at risk of developing obesity and tooth decay. We need mechanisms to support and educate families in disadvantaged areas.

Another study, “How do diet trajectories develop over time?” which was published in Nutrition Journal, looked at the dietary patterns of over 900 children at 4, 8, 12, 24 and 36 months of age.

We observed that eating core foods increased rapidly in the first year of life, followed by a decline in the frequency after age two.

We identified three trajectory groups who ate core foods:

  • Low – started with low consumption of core foods and continue to consume less (29%)
  • Moderate – started with rapid consumption of core foods followed by a steady decline (44.5%), and
  • High – started with rapid consumption of core foods followed by an early decline (26.5%).

Children who had siblings, those born in single parent households, and with parents from a non-English speaking country had a low consumption of core foods over time, whereas those who were breastfed longer were associated with high intake of core foods over time.

It was pleasing to see that the longer the mother breastfed, the higher was the frequency of core foods consumption in their children over time.

However, it is important that we also educate families on age-appropriate healthy foods and work in partnership to support them, since unhealthy diet patterns lead to a number of health conditions.

Some mothers do not have enough knowledge on the amount of sugar in food. Young children’s diets are often influenced by what parents and siblings eat or drink, media advertising, and the availability of time for parents to prepare healthy meals.

A fourth paper, explored the “Impact of dietary trajectories and other factors on obesity and tooth decay”, published in Nutrients, looked at the impact of diet trajectories on health outcomes of children.

Conducted by Dr Manohar as as part of his PhD, it found that children who continued to be high consumers of discretionary foods from an early age were twice more like to be overweight or obese at 3-4 years age.

Further, infants who were breastfeed longer than 12 months were twice more likely to experience tooth decay. Most importantly, we found that low SES had an equally profound effect on both obesity and tooth decay in early childhood.

We’ve been able to show that unhealthy dietary patterns start early, and the consumption continues to increase into early childhood, highlighting the importance of establishing healthy patterns early in life.

This research will provide solid evidence to the recently announced Australian Dietary Guidelines Committee by the National Health and Medical Research Council to inform the new Infant Feeding Guidelines and Australian Dietary Guidelines.

We will continue to assess the long-term health impacts amongst these children at age 7-9 years as we are currently looking at this data. It is important that we work in close partnership with families and use integrated approaches to prevent two highly prevalent health conditions in Australian children.


Western Sydney University-based Associate Professor Amit Arora leads the Healthy Smiles Healthy Kids Study, which has investigated infant and young children feeding patterns and their links with obesity and tooth decay in early childhood. This is a joint collaboration between former Sydney South West Area Health Service (now classified as Sydney and South Western Sydney Local Health Districts), NHMRC, Western Sydney University, University of Technology Sydney, Curtin University, University of Adelaide, and University of Queensland.

Dr Narendar Manohar is a PhD researcher from Western Sydney University under the supervision of Assoc Prof Amit Arora and Prof Andrew Hayen (UTS).

Prof Hayen is Professor of Biostatistics in the School of Public Health at UTS. He is also the Deputy Head of School — Teaching and Learning.

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