In developed countries, children of a lower socio-economic status are likelier to become overweight or obese, compared to children of a higher socio-economic status.
In Australia, 33% of children residing in the poorest neighbourhoods are overweight or obese, while the figure is 19% in the wealthiest neighbourhoods.
Children of a higher socio-economic position tend to consume the recommended intakes of fruits and vegetables, while those of a lower socio-economic position tend to consume discretionary food and drink (defined as food and drink containing added fat, sugar and / or salt), such as sugar-sweetened beverages, fruit juice, snacks and fast food.
In fact, 40% of Australian children's total daily energy intake comes from discretionary food and drink.
However, previous studies have not investigated the extent to which children's intake of discretionary food and drink influences the progression of such inequalities in childhood.
As such, researchers at Australia's Monash University and Deakin University conducted a prospective study using data on 3,190 children from the nationally representative Longitudinal Study of Australian Children.
Over a 10-year period, they recorded the cumulative consumption of discretionary hot foods, sweet and savoury snacks, and sweet drinks starting from the children's first year of life, and the impact this had on the link between socio-economic position and the children's BMI z-score at the age of 10 or 11.
Subsequently, they observed that at 10 to 11 years old, the mean BMI z-score was 0.17 among the children of the highest socio-economic status, 0.33 among those in the middle, and 0.47 among those of the lowest socio-economic status.
Additionally, the prevalence of being overweight or obese across the three groups was 16.6%, 25.7% and 32.7%, respectively.
The researchers also reported that 11% of the difference in BMI-z-score was "mediated by socio-economic differences in (the) consumption of sweet drinks and discretionary hot foods, including pies and hot chips, throughout childhood".
This led them to state that the intake of discretionary hot food and sweet beverages from the first year of life was a likely contributor to the development of inequalities in excess weight among children.
Reduced inequality = reduced weight?
They added that these results "may be generalizable across high-income countries" where such socio-economic gradients among overweight and obese children exist, and that reducing the consumption of such food and drink would help children achieve a healthier weight and lessen socio-economic inequalities in weight gain among them.
They further stated that this a combination of interventions "across the gradient of socio-economic disadvantage" would be necessary to achieve these goals, and should include population-level programmes for the socio-economically disadvantaged.
They concluded: "Evaluation of interventions and ongoing population health monitoring will be critical to our understanding of the impacts of population level and targeted interventions across the socio-economic gradient.
"Further research is also required to improve understanding of the role of other important modifiable obesity-related risk factors on socio-economic differences in children’s weight."
Source: International Journal of Epidemiology
"Contribution of discretionary food and drink consumption to socio-economic inequalities in children’s weight: prospective study of Australian children"
Authors: Alexandra Chung, et al.