Academics from the Johns Hopkins Bloomberg School of Public Health assessed the effects of proving clear and visible caloric information on sugar-sweetened beverages (including fruit juice and sodas) on purchase frequency at corner stores in Baltimore city.
Study leader, assistant professor Sara Bleich, said: “The reason for this is threefold: we know that adolescents – particularly black adolescents – are at higher risk of obesity. We know that calories contained in liquid form tend not to be well compensated for.
“Meaning that, if you drink calories, you tend to not eat less solid food because of it. And we also know that, in general, Americans have low numeracy and low literacy skills when it comes to calories.”
The study design at four corner stores in low-income, predominantly black neighbourhoods in Baltimore involved posting three signs with the following information.
- ‘Did you know that a bottle of soda or fruit juice has about 250 calories?’
- ‘Did you know that a bottle of soda or fruit juice has about 10 per cent of your daily calories?’
- ‘Did you know that working off a bottle of soda or fruit juice takes about 50 minutes of running?’
The researchers collected data for 1,600 beverage sales to black adolescents agent 12-18, which included 400 during a baseline period and 400 each for each of the three interventions.
At baseline, sugar-sweetened beverages accounted for 93.3 per cent of all beverage purchases, compared to 87.5 per cent when question one was displayed, 86.5 per cent for question two and 86 per cent for question three.
Iced tea on ice
The researchers noted that purchases of iced tea and sports drinks fell after the intervention, while purchases of water and juice increased, perhaps (they said) because adolescents regarded the latter as a healthier choice.
Reflecting on the results, Bleich said: “The results are really encouraging. We found that providing any information (via the three signs) relative to none, reduced the likelihood that they would buy a sugary beverage by 40 per cent.
“Of those three signs, the one that was most effective was the physical activity equivalent: telling the adolescent that [working off] a bottle of soda is about 50 minutes of jogging.”
Bleich added: “We found that when that sign was posted, the likelihood that they would buy a sugary beverage reduced by around 50 per cent.”
Title: ‘Reduction in purchases of sugar-sweetened beverages among low-income, black adolescents after exposure to caloric information’.
Authors: S.N Bleich, B.J Herring, D.D.Flagg, T.L Gary-Webb
Source: American Journal of Public Health, December 2011, doi:10.2105/AJPH.2011.300350