Contribution of discretionary food and drink consumption to socio-economic inequalities in children's weight: prospective study of Australian children

Background: In high-income countries, children with a lower socio-economic position (SEP) are more likely to gain excess weight compared with children with a higher SEP. The extent to which children's consumption of discretionary food and drinks contributes to the development of these inequalities over childhood has not been examined. Methods: The study sample comprised 3190 children from the nationally representative Longitudinal Study of Australian Children. Linear and logistic regression models were fitted in accordance with the product of coefficients mediation method to determine the contribution of cumulative consumption of sweet drinks, discretionary hot foods, savoury snacks and sweet snacks from the first year of life, over a period of 10 years, on the relationship between SEP and children's body mass index (BMI) z-score at age 10-11 years. Results: At age 10-11, mean BMI z-score was 0.17 in the highest SEP tertile, 0.33 in the middle and 0.47 in the lowest tertile. Corresponding values for overweight and obesity prevalence were 16.6%, 25.7% and 32.7%, respectively. Eleven per cent [95% confidence interval (CI) 4.77%, 19.84%] of the observed difference in BMI z-score at age 10-11 years was mediated by socio-economic differences in consumption of sweet drinks and discretionary hot foods including pies and hot chips throughout childhood. Conclusions: Findings indicate that consumption of sweet drinks and discretionary hot food, from the first year of life, is likely to contribute to the development of inequalities in excess weight among children. Poor dietary intake is a key risk factor for excess weight gain among children and a reduction in discretionary food and drinks is likely to contribute to the dual goal of improving overall weight and reducing socio-economic inequalities in weight gain across childhood. To maximally reduce inequalities in weight gain across childhood, additional determinants must also be identified and targeted.