Children gain less weight and accumulate less fat when sugar-free, non-caloric beverages are substituted for sugar-sweetened beverages
- Correspondence to: Dr Rachel K Johnson
Department of Nutrition and Food Sciences, The University of Vermont, 225B Marsh Life Sciences, 109 Carrigan Building, Burlington, VT 05405, USA;
Commentary on: de Ruyter JC, Olthof MR, Seidell JC, et al. A trial of sugar-free or sugar-sweetened beverages and body weight in children. N Engl J Med 2012;367:1397–406.
Childhood obesity is one of the world's most pressing public health challenges.1 Sugar-sweetened beverages (SSBs) have been associated with childhood overweight.2 These beverages are the number one source of calories in children's diets in the USA3 and are especially problematic because they are void of critical nutrients and elicit weak satiety responses.4 However, studies linking SSBs with obesity have been largely observational and thus have not established cause and effect. Data from randomised controlled trials demonstrating the definitive effect of SSBs on childhood weight gain are needed.
The study by de Ruyter and colleagues was a double-blind, randomised trial conducted with 641 normal-weight Dutch schoolchildren aged 4 years 10 months to 11 years 11 months who regularly consumed SSBs. The children were randomly assigned to receive 1 can per day of an SSB (104 calories/8 oz) or an identical looking, similar-tasting non-caloric beverage sweetened with non-nutritive sweeteners (acesulfame potassium and sucralose). The children received the beverages at school. Teachers checked to ensure the children consumed the beverages during their morning break in class. Adherence was monitored by randomly collecting returned cans as well as measuring the sucralose concentration in subjects' urine. The primary outcome was body mass index (BMI) z score; a useful measure of overweight and obesity. More accurate measures of body fatness, including skinfold thicknesses and electrical impedance, were secondary outcomes. The trial lasted for 18 months.
Masked replacement of an SSB with a sugar-free, non-caloric beverage significantly reduced weight gain and fat accumulation in this large sample of normal-weight Dutch schoolchildren. The mean weight gain in the SSB group (n=322) was 7.37 vs 6.35 kg in the sugar-free group (n=319) (p value for difference <0.001). The SSB group had a greater increase in BMI z score (p=0.001), skinfold thicknesses (p=0.02) and fat mass measured by electrical impedance (p=0.02).
This was a successfully executed, controlled trial with a randomised, double-blind design; considered the gold standard for evaluating an intervention's effectiveness.5 The limitations of the study included a 26% drop-out rate. However, in the period when the drop-outs were participating in the study, their differences in weight and body fat measures were similar to the children who completed the study. The study was limited to healthy, normal-weight Dutch children, most of whom were Caucasian. Thus, generalisation of the findings to overweight or obese children and children from different ethnic groups is limited. Yet the study had numerous strengths including a robust design, large sample size, the use of a biomarker to confirm adherence to the intervention, and precise outcome measurements. The question remains whether or not the weight differences and reduced body fatness can be sustained without the direct provision of non-caloric beverages. It has yet to be determined whether education alone is sufficient to change SSB consumption patterns in children.
Opponents of public health messages to reduce SSBs argue that obesity is not uniquely caused by any single food or beverage. Nonetheless, this study provides convincing evidence that eliminating one single category of beverage can have a meaningful effect on children's body fatness. The study gives credence to public health education campaigns intended to discourage consumption of SSBs6; regulations that ban the sale of large-sized, single serving containers of SSBs7; and proposed legislation to tax SSBs8 in an effort to reduce consumption and raise revenue for obesity prevention.