For kids, small soda taxes don’t make a big difference

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Small scale increases in the cost of soda likely have little impact on childhood obesity, according to a study published in the journal Health Affairs. Soda taxes have been proposed as a means for fighting obesity by several prominent health researchers, and some public health officials have sparked controversy by advocating for steep taxes on soft drinks to deter consumption. Yet, while previous research has shown that increased cost of soda leads to decreased consumption—a 10% price increase corresponds with an 8% reduction—there has been little analysis of how increased cost actually influences weight, and no analysis of this impact on children, they argue. To remedy that, the team of researchers from the RAND Corporation, the University of Illinois at Chicago and the Institute for Health Research and Policy used current data on state soda taxes and children’s weight to assess the influence of soda tariffs both on consumption and childhood obesity.

Using data from a national study of elementary school-aged children collected in spring 2004, researchers analyzed body mass index (BMI), total weekly consumption of sugary drinks, and consumption during school hours for more than 7,000 children. They then analyzed state soda taxes (taxes specific to carbonated, sweetened beverages), from the same time period. The study authors found that, across the study population, there was no “significant relationship between differential soda taxes and overall soda consumption.” And the relatively small tax percentages included in the study (up to 7%) represent figures similar to those proposed by advocates of soda taxes, the study authors point out, but the “results suggest that such small taxes are unlikely to have measurable effects on soda consumption or obesity among children overall.” In order for soda taxes to effect any real change in childhood obesity, they would likely have to be far bigger, the authors conclude—on the scale of the 18% tax that was considered in New York City in 2009, perhaps.

In the study, children reported drinking an average of six or more sodas per week, with 25% consuming soda daily, and 10% drinking two or more sodas each day. Additionally, researchers found that most children seldom bought soft drinks at school: 80% of kids included in the study never purchased soda at school. Yet the 20% of students who did purchase sodas in school tend to do so regularly—averaging three sodas per week. While the researchers ultimately concluded that “increasing the differential tax on soda doesn’t affect total soda consumption,” they identified several factors that did: children with college-educated mothers, girls and Asian children tended to consume less soda, while children who watched more TV tended to consume more, the researchers found. Researchers found that African American children and kids who watched a lot of TV were the most likely to purchase sodas in school.

While, overall, small scale soda taxes showed little tangible benefit in reducing obesity in children, researchers did find that, when they specifically analyzed the effect on high-risk children—including those from low-income families, African Americans, and kids who watched a lot of TV—taxes on the high end of the range studied were associated with lower BMI (as well as lower total soda consumption, though, due to small sample size, those figures weren’t statistically significant). While, for most children, soda taxes have little impact on obesity risk, for children at particularly high risk for obesity, they may make some difference. As the researchers sum up: “… for the full population, the range of variation in taxes does not predict total consumption or BMI. Larger taxes could have more pronounced effects at the population level. Among children at higher risk for obesity, however, even taxes in the range of current rates can affect outcomes.”