Food Pricing Strategies, Population Diets, and Non-Communicable Disease: A Systematic Review of Simulation Studies

A systematic review of simulation studies conducted by Helen Eyles and colleagues examines the association between food pricing strategies and food consumption and health and disease outcomes. Background: Food pricing strategies have been proposed to encourage healthy eating habits, which may in turn help stem global increases in non-communicable diseases. This systematic review of simulation studies investigates the estimated association between food pricing strategies and changes in food purchases or intakes (consumption) (objective 1); Health and disease outcomes (objective 2), and whether there are any differences in these outcomes by socio-economic group (objective 3). Methods and Findings: Electronic databases, Internet search engines, and bibliographies of included studies were searched for articles published in English between 1 January 1990 and 24 October 2011 for countries in the Organisation for Economic Co-operation and Development. Where ≥3 studies examined the same pricing strategy and consumption (purchases or intake) or health outcome, results were pooled, and a mean own-price elasticity (own-PE) estimated (the own-PE represents the change in demand with a 1% change in price of that good). Objective 1: pooled estimates were possible for the following: (1) taxes on carbonated soft drinks: own-PE (n = 4 studies), −0.93 (range, −0.06, −2.43), and a modelled −0.02% (−0.01%, −0.04%) reduction in energy (calorie) intake for each 1% price increase (n = 3 studies); (2) taxes on saturated fat: −0.02% (−0.01%, −0.04%) reduction in energy intake from saturated fat per 1% price increase (n = 5 studies); and (3) subsidies on fruits and vegetables: own-PE (n = 3 studies), −0.35 (−0.21, −0.77). Objectives 2 and 3: variability of food pricing strategies and outcomes prevented pooled analyses, although higher quality studies suggested unintended compensatory purchasing that could result in overall effects being counter to health. Eleven of 14 studies evaluating lower socio-economic groups estimated that food pricing strategies would be associated with pro-health outcomes. Food pricing strategies also have the potential to reduce disparities. Conclusions: Based on modelling studies, taxes on carbonated drinks and saturated fat and subsidies on fruits and vegetables would be associated with beneficial dietary change, with the potential for improved health. Additional research into possible compensatory purchasing and population health outcomes is needed. Background: For the first time in human history, non-communicable diseases (NCDs) are killing more people than infectious diseases. Every year, more than 35 million people die from NCDs—nearly two-thirds of the world's annual deaths. More than 80% of these deaths are in developing countries, where a third of NCD-related deaths occur in people younger than 60 years old. And NCDs are not just a growing global public health emergency. They are also financially costly because they reduce productivity and increase calls on health care systems worldwide. Cardiovascular diseases (conditions that affect the heart and circulation such as heart attacks and stroke), cancers, diabetes, and chronic respiratory diseases (long-term diseases that affect the lungs and airways) are responsible for most NCD-related illnesses and death. The main behavioral risk factors for all these diseases are tobacco use, harmful use of alcohol, physical inactivity, and unhealthy diets (diets that have a low fruit and vegetable intake and high saturated fat and salt intakes). Why Was This Study Done?: Improvements in population diets and reductions in salt intake are crucial for the control and prevention of NCDs, but how can these behavioral changes be encouraged? One potential but poorly studied strategy is food pricing—the introduction of taxes on unhealthy foods (for example, foods containing high levels of saturated fat) and subsidies on healthy foods (for example, foods high in fiber). However, although a tax on soft drinks, for example, might decrease purchases of these high-sugar drinks, it might also increase purchases of fruit juices, which contain just as much sugar and energy as soft drinks (“compensatory purchasing”), and thus undermine the intended health impact of the tax. Because randomized controlled trials of the effects of food pricing strategies are difficult to undertake, many researchers have turned to mathematical models (sets of equations that quantify relationships between interventions and outcomes) to provide the evidence needed to inform policy decisions on food taxes and subsidies. In this systematic review (a study that uses predefined criteria to identify all the research on a given topic), Helen Eyles and colleagues investigate the association between food pricing strategies and food consumption and NCDs by analyzing the results of published mathematical modeling studies of food pricing interventions. What Did the Researchers Do and Find?: The researchers identified 32 studies that met their predefined inclusion criteria, which included publication by researchers in a member country of the Organisation for Economic Co-operation and Development (a group of largely developed countries that promotes global development). Most of the studies were of low to moderate quality and provided uncertain and varying estimates of the impact of pricing on food consumption. Where three or more studies examined the same pricing strategy and consumption or health outcome, the researchers calculated the average change in demand for a food in response to changes in its price (“own-price elasticity”). For taxes on carbonated soft drinks, the average own-price elasticity was −0.93; that is, the models predicted that a 1% increase in the price of soft drinks would decrease consumption by 0.93%. The modeled reduction in the proportion of energy intake from saturated fat resulting from a 1% increase in the price of saturated fats was 0.02%. Finally, although the researchers' analysis suggested that for each 1% reduction in the price of fruits and vegetables, consumption would increase by 0.35%, they also found evidence that such a subsidy might result in compensatory purchasing, such as a reduction in fish purchases. What Do These Findings Mean?: These findings suggest that pricing strategies have the potential to produce improvements in population diets, at least in developed countries, but also highlight the need for more research in this area. Notably, the researchers found insufficient data to allow them to quantify the effects of pricing strategies on health or to analyze whether the effect of pricing strategies is likely vary between socio-economic groups. Given their findings, the researchers suggest that future modeling studies should include better assessments of the unintended effects of compensatory purchasing and should examine the potential impact of food pricing strategies on long-term health and NCD-related deaths. Finally, they suggest that robust evaluations should be built into the implementation of food pricing policies to answer some of the outstanding questions about this potential strategy for reducing the global burden of NCDs. Additional Information: Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001353.