Sweet success: will sugar taxes improve health?

Abstract

Mexico continues to build on the success of its tax on sugary drinks, with new analysis showing further reductions in sales of sugar-sweetened beverages in the second year after its implementation. The results provide potential hints of optimism about the effect of similar strategies in other countries—including the UK, where a levy on sugary drinks is set to take effect in April, 2018. Mexico's 10% tax on sugar-sweetened beverages, implemented in January 2014, resulted in a 5·5% decrease in sales by the end of that year. The 2-year data show an impressive further 9·7% drop in sales in 2015, with the largest decrease amongst the most socioeconomically disadvantaged households—those also disproportionately affected by diet-related conditions such as type 2 diabetes and obesity. This is welcome news, particularly in the wake of industry claims of a 2015 rebound in soda sales in Mexico and a surge in Mexican soda volumes. The 2-year effect of Mexico's tax suggests evidence for gradual habituation away from sugary drinks (in Mexico, sales of bottled water increased after the tax), suggesting that the long-term impact of price changes could outpace the short term effects. Whether similar sales decreases will be seen in other countries that have enacted similar taxes, such as France (enacted in 2012), Hungary (2012), and Finland (2016), remains to be seen. The highest taxation levels (up to 25%) were imposed in the city of Berkeley, USA in 2015, resulting in a 21% plummet in sales of sugary beverages in low-income neighbourhoods in the first 4 months. The UK levy will impose a tax on manufacturers and importers on all drinks containing five or more grams of sugar per 100 mL, with a higher tax on beverages containing 8 or more grams of sugar per 100 mL (a typical can of cola contains twice that). The price tag will be lower for producers that voluntarily lower the sugar content of their products before the tax goes into effect. Indeed, some companies have already begun to reformulate their products in anticipation of the tax, including UK soft drinks company A.G. Barr and supermarket chain Tesco. Similarly, in the wake of Hungary's 2011 sugar tax, 40% of manufacturers reformulated their products by reducing or ridding them of sugar and other unhealthy ingredients such as caffeine and salt. That taxes on food and beverages reduce sales of these products is not news. The real question is to what extent sugar taxes and other similar policies will pay dividends with respect to population health. So far, the evidence is based mostly on modelling studies, but many projections are optimistic. Assuming that decreased sales are a faithful proxy for decreased consumption, a recent study estimated that Mexico's 10% tax on sugary beverages would prevent nearly 190 000 new cases of diabetes over 10 years, at an average savings of Int$983 million (roughly £785 million) in related health-care costs. Combining discounts on healthy foods with taxes on unhealthy ones might boost health gains; a recent systematic review and meta-analysis showed that reducing the price of fruits and vegetables by 10% increased their consumption, with positive effects on BMI. Taking a different approach, a UK modelling study advocating for a gradual reduction in the sugar content in sweetened beverages estimated that a 40% reduction in added sugars over 5 years would reduce the number of obese adults by roughly half a million and new cases of type 2 diabetes by around 300 000. Of course, hard evidence of improved population health takes time to compile. And even when high quality health data become available, it will be very difficult to pin specific health improvements to single policy measures. After all, better health is not just about sugar. In Mexico, for example, the beverage tax is in play alongside an 8% tax on non-essential energy-dense foods and restrictions on food marketing to children. In Berkeley, USA, the beverage tax was accompanied by a vigorous public health campaign warning of the health dangers of sugary drinks. On the flip side, industry-sponsored countermeasures, such as increased advertising and promotions, would be expected to have a mitigating effect. Critics of the long-delayed UK childhood obesity strategy—of which the tax on sugary drinks is one component—argue vehemently that additional policies, such as strict restrictions on food advertising to children, are also needed (indeed many such policies were initially included in the government's plan). There is also an urgent need for careful studies to assess the effect of these policies on hard health measures in the population. In the meantime, however, the news from Mexico is encouraging, and the tax on sugary beverages is at least a step in the right direction.