Could a sugar tax help combat obesity?

Yes—Sirpa Sarlio-Lähteenkorva

Taxes are traditionally regarded as a source of revenue, but they can also be used as tools in health policy. Indeed, taxes on alcohol and tobacco have been widely used for decades and reduce consumption.1 2 Many countries have also recently passed legislation to introduce or increase taxes on specific food items such as soft drinks, sweets, chocolate, ice cream, or other unhealthy foods, often aiming to combine fiscal and health benefits.3 Although data are limited, emerging evidence indicates that food taxes can influence consumption.4 5 6

However, improving dietary habits this way is more complicated than limiting alcohol or tobacco use. Food is a necessity, and overall consumption is relatively insensitive to price changes. When some foods become more expensive consumers tend to look for cheaper substitutes. These cross elastics of demand need to be considered carefully when planning food taxes. It has been suggested that to influence consumption the price increase has to be at least 20%,4 and consumption of some foods is less sensitive to price changes than for others. Limited data come mostly from modelling studies. However, increasing evidence suggests that taxes on soft drinks, sugar, and snacks can change diets and improve health, especially in lower socioeconomic groups, where price elasticity is high.5 The potential for improved health is greatest when combined with incentives for choosing healthier foods.5