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A UNC-Chapel Hill study of beverage consumption in a South African township shows that a country-wide tax on sugary beverages has worked to influence more healthy personal choices, with individuals reporting a reduction in the amount of sugar they drink.

“Taxed and untaxed beverage intake by South African young adults after a national sugar-sweetened beverage tax: a before-and-after study,” was published May 25, 2021, in PLOS Medicine

This study is the first to parse out the law’s impact on individual consumption behaviors separately from changes in sugar intake due to reformulation—a term used when industry changes the ingredients or nutrition content—of beverages in response to the sugar-content based Health Promotion Levy that South Africa implemented in April 2018.

These findings contribute to the growing evidence that sugar-content based taxes can improve health by reducing consumption of sugar-sweetened beverages (SSBs) and encouraging product reformulation, says Michael Essman, PhD, a post-doctoral research scholar at the UNC Gillings School of Global Public Health and the study’s lead author. Other Gillings School authors on the study are Lindsey Smith Taillie, PhD, Shu Wen Ng, PhD, Barry Popkin, PhD.

“This study took place in a high-SSB consuming, but low-income, population,” says Essman. “That’s important because this is a high-risk population. Consuming a lot of sugary beverages can lead to chronic disease, like diabetes, and those who have a low income may have less access to health care, and therefore be more vulnerable to the effects of chronic diseases. When we see a shift like this, we know it reduces the risk of disease.”

The 2018 levy imposed a 11% tax on certain SSBs to reduce the risk of type 2 diabetes and other noncommunicable diseases, such as hypertension and cardiovascular disease. By imposing the levy on products with more than four grams of sugar per 100 milliliters, the tax incentivized beverage manufacturers to reduce sugar content below threshold to avoid the tax or nearer to the threshold so they would be taxed less.

Researchers assessed the dietary intake of predominantly low-income adults aged 18-39 years in Langa – a township in Cape Town, South Africa – by collecting single-day dietary recalls from repeat cross-sectional surveys before and after the implementation of the beverage tax. Dietary recalls are different from a food diary, where one may amend their intake in anticipation of reporting it. When researchers ask for recalls after-the-fact, they are getting a more accurate representation of true behaviors.

Total reduction in sugar from taxed beverages was 31%. Researchers determined that participants’ changes in beverage intake accounted for 22% in sugar while beverage reformulation accounted for 9% in sugar.

“The HPL in South Africa was amazingly impactful for such a small tax,” says Popkin.

Essman says policymakers should take note of how sugar-based taxes can effectively accomplish the goals of reducing sugar intake and encouraging the reformulation of products as a way to improve public health.

“Our study contributes to and strengthens the SSB taxes evidence,” says Essman. “This is a model for other countries who want to reduce the prevalence of chronic diseases related to poor diet.”