Small sales taxes on soft drinks are not enough to curb soda consumption among children, reveals a new American study.
The RAND Corporation study points out that these small taxes may reduce consumption in some subgroups such as children at greater risk for obesity, but reducing consumption for all children would require larger taxes.
Lead author Roland Sturm, a senior economist at RAND, a nonprofit research organization, said: "If the goal is to noticeably reduce soda consumption among children, then it would have to be a very substantial tax.
"A small sales tax on soda does not appear to lead to a noticeable drop in consumption, led alone reduction in obesity."
Taxes on soft drinks and other sugar-sweetened beverages have been proposed as part of many anti-obesity efforts, with the goal being to discourage consumption of the high-calorie drinks in order to curb excess weight gain.
The study team estimated the potential effect of soft drink taxes on children's consumption and weight by examining differences in existing sales taxes on soft drinks between states.
Details about state soda taxes were compared to information about weight and soda consumption among 7,300 children enrolled in the Early Childhood Longitudinal Study, which has been gathering information about a national group of children for many years.
Children studied reported drinking an average of six sodas per week, but there was wide variation among the group.
Fifteen percent reported drinking no sodas in the prior week, while 10 percent consumed two or more sodas per day. The amount of soda purchased at school was small.
The higher sales tax on soda in some states did seem to reduce soda consumption and curb weight gain among children at higher risk for obesity - those who were heavier, children from low-income families, African-American children and those who watched a lot of television.
Children in all these groups drank more soft drinks than children in general.
The impact was more pronounced for children from these groups who had access to soft drinks at school.
According to the study, price effects may be stronger in school settings where cafeterias or vending machines round prices up, although there are alternative explanations.
Sturm said: "Soda taxes do have the potential to help reduce children's consumption of empty calories and have an impact on obesity, but both their size and how they are structured are key to whether they create measurable impact."
The research has appeared in the journal Health Affairs.