The Potential Impact of a 20% Tax on Sugar-Sweetened Beverages on Obesity in South African Adults: A Mathematical Model

Abstract

Background/ObjectivesThe prevalence of obesity in South Africa has risen sharply, as has the consumption of sugar-sweetened beverages (SSBs). Research shows that consumption of SSBs leads to weight gain in both adults and children, and reducing SSBs will significantly impact the prevalence of obesity and its related diseases. We estimated the effect of a 20% tax on SSBs on the prevalence of and obesity among adults in South Africa.MethodsA mathematical simulation model was constructed to estimate the effect of a 20% SSB tax on the prevalence of obesity. We used consumption data from the 2012 SA National Health and Nutrition Examination Survey and a previous meta-analysis of studies on own- and cross-price elasticities of SSBs to estimate the shift in daily energy consumption expected of increased prices of SSBs, and energy balance equations to estimate shifts in body mass index. The population distribution of BMI by age and sex was modelled by fitting measured data from the SA National Income Dynamics Survey 2012 to the lognormal distribution and shifting the mean values. Uncertainty was assessed with Monte Carlo simulations.ResultsA 20% tax is predicted to reduce energy intake by about 36kJ per day (95% CI: 9-68kJ). Obesity is projected to reduce by 3.8% (95% CI: 0.6%–7.1%) in men and 2.4% (95% CI: 0.4%–4.4%) in women. The number of obese adults would decrease by over 220 000 (95% CI: 24 197–411 759).ConclusionsTaxing SSBs could impact the burden of obesity in South Africa particularly in young adults, as one component of a multi-faceted effort to prevent obesity.

The impact on productivity of a hypothetical tax on sugar-sweetened beverages

“…It would also be valuable to perform similar analyses in other settings for obesity interventions. The results are consistent with similar modelling work in other countries (25,26). If similar data are available, the methodology used in this paper for estimating productivity gains due to a tax on SSBs may also be applied to other countries.…”

“…Briggs et al (25) estimated that a hypothetical 20% valoric tax (flat sales tax) on SSBs would reduce the prevalence of obese adults by 1.3% in the United Kingdom (UK). Similarly, Manyema et al (26) estimated that a hypothetical 20% tax on SSBs in South Africa would reduce potential adult obesity prevalence by 3.8% in males and 2.4% in females.…”

“…All health outcomes are modeled through changes in body mass resulting from a change in energy consumption, and no direct effects of SSBs consumption on health outcomes are estimated. Similar analytical models of the cost-effectiveness of taxes on SSBs have been constructed for the UK and South Africa (25,26).…”

Introduction of "Sugar Tax" in South Africa: Placebo or panacea to curb the onset of cardio-metabolic diseases?

“…Africa. (36) In addition, it is estimated that the incidence of stroke over the next 20 years will be reduced by 85 000. (37) It is, …”

Persistent burden from non-communicable diseases in South Africa needs strong action

“…This is expected to cut the number of obese people by 220 000 in 3 years. [13] However, policy development on alcohol harm reduction has been slow.…”