Introduction: A proposed tax on sugar sweetened beverages (SSBs) features prominently in the suite of regulatory approaches to address population weight gain. However, the effect of this tax across socioeconomic strata is unclear. We aimed to synthesise the evidence of the effect of a tax on SSBs across socioeconomic groups.
Methods: Electronic databases and grey literature were searched to identify studies that included terms for SSBs, price or taxation, and socioeconomic position (SEP). Studies were included if they reported an effect of changes in SSB price on purchases or health outcomes by SEP.
Results: The search returned 286 studies, of which nine were included. All included studies examined beverage demands using price elasticity estimates; six of these used this data to model the impact of a hypothetical tax. Reported outcomes included change in SSB purchase, and changes in energy intake, weight, prevalence of obesity and tax burden. All studies used household income as their marker of SEP. Settings included the UK, USA, NZ, Australia and Brazil. Five studies reported a significant effect on the outcome across all income groups with a greater magnitude of effect for lower income groups. Four studies reported equal benefits for high and low income groups. Four of the five studies reporting the tax burden described the tax as regressive, but the amount paid in tax was negligible for all income groups. One study reported the tax burden as progressive.
Conclusion: Taxation of SSBs is likely to be at least equally effective for those with a lower household income relative to those with a higher household income. Although the financial tax burden is likely to be regressive, the overall tax burden is expected to be small. A tax on SSBs shows great promise for reducing the population burden of excess weight and is unlikely to exacerbate existing socioeconomic inequalities in weight.