How many Australian adolescents have frequent toothache?

Eight percent and could it be from sugar-sweetened beverages? This study highlights toothache is 2.5 times more likely where > 500ml per day of sugar-sweetened beverage is consumed

Soft drinks, fruit juice and energy drink contribute to sugar intake

Too much sugar in the diet is a public health concern and linked to unhealthy weight gain and dental caries.  WHO recommend sugar intake should be less than 10% of total energy intake and substantial oral health benefits have been recognised when sugar intake is less than 5% of total energy intake (1).

An earlier blog discusses the WHO sugar recommendation

However, in Australia, many adolescents exceed this recommendation and sugar contributes to 15% of adolescents energy intake (2).  Sugar-sweetened beverages (SSB) are a contributor of added sugar in the Australian adolescent diet.  Dr Louise Hardy, from the University of New South Wales, looked at the oral health issues (OHI), the prevalence of obesity and its association with the consumption of sugar-sweetened beverages in Australian adolescents in her recent study (3).

What causes tooth decay?

Acid is a by-product of bacteria in the mouth, feeding on sugars from food.  It is the acid which decays the teeth.

The authors (from the study) say …

There were clear and consistent associations between OHI and the consumption of energy, sports drinks and flavoured water, more so than the traditional soft drink. Additionally, the prevalence of unhealthy weight was higher in the consumers of these same drinks.

This was a concern, as the perception of these, more modern, beverages as a healthy alternative is at the expense of healthy teeth.

Sports drinks are primarily marketed to provide hydration during physical activity.  Energy drinks are promoted to provide increased energy, enhance mental alertness, physical performance and better health with added antioxidants and vitamins but this is all detrimental to teeth, and there are other discussions about whether young people require drinks with caffeine and other stimulants.

Reducing the frequency and volume of SSBs to young people could have a significant impact on adolescent oral health.

Source of data and its limitations

This cross-sectional study (3) used data collected from the 2015 NSW Schools Physical Activity and Nutrition Survey (SPANS).  The 3,671 participants were aged between 10 and 16 years.

Trained field staff collected height and weight measurements and a weight to height ratio (WtH) were calculated.

The consumption of SSB data was collected through a validated short food frequency questionnaire (FFQ) and included soft drinks, diet soft drinks, sports drinks, fruit juice, flavoured water and energy drinks. Even though the FFQ was validated, it did have inconsistencies with the quantities of SSB’s consumed e.g. the question on energy drinks was about times consumed (per week) whereas the other SSB questions collected volume per day or week, so some adjustments were made to standardise this inconsistency.

There was no clinical dental examination to determine the prevalence of OHI.  Instead, two questions were asked from the National Dental Telephone Survey.  These validated questions have a strong correlation with the presence of dental caries.  An OHI was defined where there were ‘often’ or ‘very often’ toothaches or problems with the mouth or teeth so some foods were avoided.

The statistical analysis considered the frequency of teeth brushing (OHI) and level of physical activity (for weight), along with age, sex, socio-economic status, residence (urban or rural) and language background.

As expected the data showed an association between SSB and OHI

In total, 8% (266 adolescents) of the study group experienced frequent OHI.  Eleven percent (384 adolescents) of the study group did not drink SSBs.

The overall outcome showed 16% (539 adolescents) of the study group drank more than 2 cups of any SSB per day and were 2.5 to 3 times more likely to have OHI than someone who did not drink SSBs.  The result was dose responsive, therefore, the prospect of an OHI increased as consumption of SSB’s increased.

Looking at one class of SSBs, the prevalence of OHI was highest in diet soft drinkers but this only affected 2% (83 adolescents) of the study group.  These 83 adolescents consumed more than 1 cup of diet soft drink per day and were 4-5 times more likely to have OHI than the remaining 3377 adolescents, who consumed less than 1 cup of diet soft drink per day.

For consumers of diet soft drinks the prevalence of OHI was considered high and without a reason, even though it affected only a small group the researchers felt it could be worth exploring whether the prevalence was due to the artificial sweeteners or some other habit undertaken by this segment of the population i.e. sucking confectionary?

In another class, 20% (671 adolescents) of the study group regularly consumed energy drinks and were twice as likely to have OHI as those who did not drink energy drinks at all.

One person could be in more than one class of SSB as more than half the study group consumed a range of SSBs.

But no association between SSBs and weight …

In total, 27% (961 adolescents) were in an unhealthy weight range.

The overall result did not show any association of SSBs with unhealthy weight.  This is not consistent with meta-analyses suggesting higher intakes of SSBs are associated with unhealthy weight outcomes.  However, this study showed regular consumers of energy drinks were 1.3 to 1.6 times more likely to have an unhealthy weight or WtH ratio than non-consumers of energy drinks.

This study adds weight to the argument that adolescents should reduce their consumption of sugar-sweetened beverages

NSW Ministry of Health funded this study and the authors state no conflicting interests.


  1. World Health Organisation. Guideline: Sugars intake for adults and children. Geneva: World Health Organisation, 2015.
  2. Lei L, Rangan A, Flood V, Louie J. Dietary intake and food sources of added sugar in the Australian population. British Journal of Nutrition 2016;115:868-77. doi: 10.1017/S0007114515005255.
  3. Hardy LL, Bell J, Bauman A, Mihrshahi S. Association between adolescents’ consumption of total and different types of sugar-sweetened beverages with oral health impacts and weight status. Australian and New Zealand Journal of Public Health:n/a-n/a. doi: 10.1111/1753-6405.12749.


Sugar and New Zealand children

Can we be more responsible for what our children eat?

  • High sugar intake is a known variable in the obesity equation
  • Obesity is expensive, avoidable, claims lives and life quality
  • New Zealand adults (and probably children) consume more dietary sugars than recommended by World Health Organisation

The cost of sugar

Obesity costs New Zealand NZ$ 624,000,000 per annum (last calculated in 2006) [1]. This is likely to be higher now as New Zealand has the third highest rate of obesity in the OECD – trailing behind the United States and Mexico.

These unnecessary healthcare costs come from the obesity-associated non-communicable diseases being type 2 diabetes and cardiovascular disease, gout and some cancers. More people die from non-communicable diseases (11.4%) than tobacco-related deaths (9.1%) and both are largely preventable. Life expectancy may have increased in the last 100 years but over the years gained 20 – 30% are lived in poor health [2].

Obesity is not an easy topic as there are many variables behind carrying too much weight. The drivers of obesity include diet, physical activity levels, maternal health (yes, your mother’s health during pregnancy), sleep and the obesogenic environment, where food supply and marketing promote high energy intake with energy-dense and nutritionally poor foods [3], [4].

New Zealand children

Obese children are likely to grow into obese adults. As well as the adult risks later in life, obese children have their own special health consequences: obstructive sleep apnoea, musculoskeletal problems, asthma and psychological problems (body dissatisfaction, poor self-esteem and depression) are all associated with child obesity. Additionally, their learning can suffer and they may be targeted for bullying [5].

Rates of obesity are higher in our Pacific and Maori children

Eleven out of 100 NZ children (2-14 years) are obese and another 21 (out of the same 100) are in the overweight category. Rates are higher in Pacific and Maori children – 61% and 44% respectively are overweight or obese [4].

What is even more disconcerting is 50% of parents of obese children do not believe their child is overweight – this is higher in obese children aged 2-4 years where 90% of parents do not consider their child to be neither under- or overweight [6].  This is another story!

High sugar intake is one of the determinants of a poor diet and a contributor to obesity. One-quarter of sugar in a child’s diet comes from sugar-sweetened beverages [7], which are of low nutritional quality leading to a poor diet, weight gain and associated risks. The consumption of high sugar food generally displaces the consumption of more nutritious foods and increases the energy intake.

Sugar Recommendations

New Zealand Ministry of Health’s (MOH) recommendation on sugar intake suggests “snacks and drinks … are … low in sugar especially added sugar ” and to “limit drinks such as fruit juice, cordial, fruit drink, fizzy drinks (including diet drinks), sports drinks and sports water” [5].

The American Heart Association (AHA) has a more cut and dry nutrition recommendation of fewer than six teaspoons of added sugar per day for children 2-18 years.

Since 1989, World Health Organisation (WHO) has strongly recommended1 children reduce their dietary intake of free sugars to less than 10% of total energy intake (<10% EI) and in 2015 suggested a further reduction of free sugars to below 5% of total energy intake (<5% EI) [8]. This is a conditional recommendation2 and is based on very low-quality evidence where a dose-response between reduced free sugar intakes of <5% EI and reduced dental caries was observed. No evidence of harm has been identified with reducing free sugars to <5% EI [8].

The strong WHO recommendation to restrict free sugar intake to <10% EI is based on moderate quality evidence3 being [8]

  • A meta-analysis of five randomised controlled trials with interventions to encourage children to reduce their sugar intake in food and beverages. The quality of the evidence was moderate but without effect in four of the five studies i.e. no changes in weight loss, this was likely to be due to low compliance by the study participants (children) willing to follow the dietary advice intervention [9].
  • A meta-analysis of prospective cohort studies did find associations with one or more servings of sugar-sweetened beverages per day and overweight or obese children [8], [9].
  • An effect of reducing or increasing sugar is dose dependent with regards to body weight – more sugar, higher BMI [8].
  • The evidence for the effect of increasing free sugar intake on body weight in children is of low quality [8].
  • Observational studies have found moderate quality evidence for a positive association between dental caries and sugar intake [8], [9], regardless of exposure to fluoride [8].

This is where it all becomes tricky, what exactly is ‘sugar’ – total, free or added? MOH describe sugar as monosaccharides and disaccharides. WHO talk about ‘free sugar’ and AHA refer to added sugar. Sometimes when comparing sugar it is not quite ‘apples’ to ‘apples’ but more a generalisation and you need a feel for the situation
FP Sugars and the Nutritional Information Panel

And do we meet the guidelines?

The University of Sydney recently evaluated the free sugar intake of the Australian population (10) and the University of Otago has done the same for New Zealand adults (11).  The graph, below, shows the average free sugar intake as a % of energy is higher than the WHO recommendation for all age groups except 51-70 year olds.

FP003 ANZ free sugar intake
The average “free” sugar intake for the Australian and New Zealand populations is primarily higher than the recommended intake (<10% EI) from World Health Organisation

Australian children’s (2-14 years) mean intake of free sugars was between 11.5 and 13.8 of total EI.  New Zealand does not have a free sugar intake calculated for NZ children.  My rough calculation of children’s free sugar intake, based on the 2002 Nutrition Survey for Children, was an average of 12% for boys and girls aged 2-14 years4 – higher than the recommendation but a formal study is required as my data was old and limiting.  Perhaps it is time for another Children’s Survey.

So now what?

Awareness of what is in our foods is key – excess sugar is associated with excess body fat, NZ children are consuming too much sugar, obese children become obese adults and obesity is associated with non-communicable diseases.

Nutrition research is in its infancy and WHO feels more research is required to evaluate different behavioural-change approaches to help promote the reduction of free sugars in children thus creating higher compliance rates in randomised controlled trials [8].

I cannot wait that long and feel that we are all in this together and need to take personal responsibility with regards to our (and our children’s) sugar consumption. Is it necessary to regularly buy sweet treats for our children – is this an act of love?


1. Lal A, Moodie M, Ashton T, Siahpush M, Swinburn B. Health care and lost productivity costs of overweight and obesity in New Zealand. Australian and New Zealand Journal of Public Health 2012;36(6):550-6. doi: 10.1111/j.1753-6405.2012.00931.x.

2. Ministry of Health. Health loss in New Zealand 1990-2013: A report for the New Zealand Burden of Diseases, Injuries and Risk Factor Study. Wellington: Ministry of Health, 2016.

3. Swinburn BA, Sacks G, Hall KD, et al. The global obesity pandemic: shaped by global drivers and local environments. The Lancet 2011;378(9793):804-14. doi:

4. Ministry of Health. Children and young people living well and staying well: New Zealand Childhood Obesity Programme Baseline Report 2016/2017. Wellington: Ministry of Health, 2017.

05. Ministry of Health. Food and nutrition guidelines for healthy children and young people (aged 2-18 years): A background paper. Partial revision February 2015. Wellington, New Zealand: Ministry of Health 2015.

6. Ministry of Health. Understanding excess body weight: New Zealand Health Survey. Wellington: Ministry of Health, 2015.

7. Ministry of Health. NZ Food NZ Children: Key results of the 2002 National Children’s Nutrition Survey. Wellington: Ministry of Health, 2003.

8. World Health Organisation. Guideline: Sugars intake for adults and children. 2015.

9. Te Morenga L, Mallard S, Mann J. Dietary sugars and body weight: systematic review and meta-analyses of randomised controlled trials and cohort studies. BMJ (Clinical research ed) 2012;346:e7492-e. doi: 10.1136/bmj.e7492.

10. Lei, L., Rangan, A., Flood, V., & Louie, J. (2016). Dietary intake and food sources of added sugar in the Australian population. British Journal of Nutrition, 115, 868-877. doi: 10.1017/S0007114515005255.

11. Kibblewhite, R., Nettleton, A., McLean, R., Haszard, J., Fleming, E., Kruimer, D., & Te Morenga, L. (2017). Estimating Free and Added Sugar Intakes in New Zealand. Nutrients, 9(12), 1292.


1. A strong recommendation from WHO suggests the desirable outcome from the recommendation outweigh any undesirable outcome
2. There is less certainty between the benefits and harms or disadvantages of implementing this recommendation still requires debate
3. Moderate quality of evidence = moderately confident that the true effect lies close to the estimate effect ut there is a possibility that it could be substantially different. Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate
4.Based on the median daily (total) sugar intake for NZ children (127 g for boys and 115 g for girls), 51% and 50% was from beverages, sugar and sweets, biscuits, cakes, desserts and cereals, which equates to 65 and 58 grams and my estimate of free sugar intake. Using a median energy intake of 9.1 MJ for boys and 7.8 MJ for girls from the same study, my estimated ‘free sugar’ consumption for both NZ boys and girls is 12% of energy.
Sugar produces 16.7 kJ per gram .. 65 g of sugar produces 1085.5 kJ (65 * 16.7) of energy .. this equates to 12% of total energy intake (1085.5/9100).