Calls for taxes on sugar-sweetened beverages (SSB) by health professionals and advocates continue to occupy news headlines. Many of these commentaries rely extensively on emotional justifications for implementing these taxes as a public health measure to prevent weight gain, diabetes and cavities.
Taxes on sugar sweetened beverages are not new and have been implemented in many areas in many different ways. In theory, this sounds like a great idea, but what is the actual evidence that they meaningfully impact public health?
Theoretically, given a large enough excise tax on SSB, consumption levels decrease, leading to significant improvements in weight and obesity rates. In Mexico for example, one analysis estimates that a SSB excise tax may have resulted in a 7.5% average reduction in SSB consumption, with the greatest decrease among households at the lowest socio-economic level, while an analysis of 15 cities in the United States that have implemented an excise tax on SSB estimates that the incidence of diabetes could potentially decrease by 6% within a year of the tax reaching its full effect. However, the estimates from these economic models only predict a decrease of less than one pound of body weight, with no real improvement in health. Furthermore, empirical evidence of self-reported soda consumption did not significantly change after Berkeley, CA, implemented its tax on SSB as people shifted their purchases to neighboring counties or online vendors. This may be because demand for sugar-sweetened beverages tends to be slightly inelastic among the general population when prices increase, meaning that price does not significantly influence a consumers decision to purchase them.
But at what cost? Are the actual changes in consumption or health outcomes substantial enough to be considered worthwhile? How sustainable or long-lasting are these improvements? And are there other programs or policies that would lead to more significant health outcomes and have a societal or individual cost that is equivalent to or lower than a sugar tax?
It is important to remember that while sugar taxes may be associated with improved weight status at the population level, there is no evidence that they cause improvements in actual health status. One reason may be because lifestyle choices contribute to less than a quarter of one’s of current health status and sugar-sweetened beverage consumption is just one of many lifestyle variables. A greater proportion of an individual’s health risk is due to social determinants of health such as one’s social environment, physical environment/total ecology, and health services/medical care.
Focusing the health conversation on taxing sugar-sweetened beverages may actually be distracting efforts to take action in addressing more substantial causes of poor health like low wages, poor housing conditions, access to affordable healthy food, violence and trauma, systemic oppression, and quality healthcare. Increasing the price of SSB may deter consumption of these products, but it does nothing to increase access to affordable healthy food or healthcare services in the communities that are affected most by food insecurity and diet-related health issues. Policy alternatives, like subsidizing the cost of fruits and vegetables, and investing in community-based food systems would do more to improve access to healthy choices–without the need to penalize people for taking pleasure in a sugary beverage now and then.
While the case of Mexico shows that a SSB tax may reduce consumption of the taxed beverages, they also estimated a 2.1% increase in purchases of un-taxed beverages due to the substitution of SSB with other products like juice, milk, diet soda, and even alcohol. While certain substitutions may be beneficial, a focus on decreased consumption of SSB and changes in BMI are too narrow to be meaningful. Without empirical evaluations of the SSB tax impacts on actual health outcomes, it is difficult to determine if the tax is actually worthwhile in achieving anything more than imposing administrative costs on society and placing an unnecessary burden on the individual autonomy of both healthy and unhealthy individuals.
Unfortunately, few studies have empirically evaluated the effects of taxes on sugar-sweetened beverages and the evidence that they improve public health measures is limited. Many studies in this area rely on econometric modeling rather than measuring peoples’ actual behavioral response to the tax. Before getting on the SSB tax band-wagon, health professionals should advocate for more extensive empirical research in this area as a way to promote evidence-based policy decisions in public health.
Related: Junk-food Taxes: Do They Work?