Helen Eyles and colleagues from the University of Auckland and the University of Otago (Wellington) reached these conclusions by reviewing all relevant modelling studies that investigated the association between food pricing strategies, food consumption and chronic diseases (often referred to as non-communicable diseases, which includes conditions such as cardiovascular disease and diabetes).
In their combined analysis of 32 studies (all from high-income countries from the Organisation for Economic Co-operation and Development), the authors' model predicted a 0.02% fall in energy intake from saturated fat for each 1% price increase. Likewise, a 10% increase in the price of soft drinks could decrease consumption by 1% to as much as 24%.
In contrast, the authors found that a 10% decrease in the price of fruits and vegetables could increase consumption by between 2% to 8%. However, the authors found evidence to suggest that such a subsidy might result in compensatory purchasing with people buying less of other healthy products, such as fish, or more of less healthy products (e.g. sugar), which may not be beneficial to health overall.
The authors also found that studies that compared food pricing strategies by socio-economic group estimated improved health outcomes for those on lower incomes, which may be relatively greater than for those on higher incomes. This suggests that food pricing strategies also have the potential to reduce inequalities.
The authors say: "Based on modelling studies, taxes on carbonated drinks and saturated fat and subsidies on fruits and vegetables are associated with beneficial dietary change, with the potential for improved health. "
The authors continue: "It must be noted that the impact of any given food tax or subsidy is likely to differ by country depending on factors such as the type of tax system implemented, health status, co-existent marketing, cultural norms, expendable income, and the social role of food."
The authors add: "Given the limitations of the current evidence, robust evaluations must be planned when food pricing policies are implemented by governments."
The authors conclude: "Additional research into possible compensatory purchasing and long-term population health outcomes for different socio-economic groups is needed."
In response to this review, Michael Marlow, Ph.D., Economics Professor, California Polytechnic State University, said:
"This review has some inherent concerns. First of all, the authors admit what they are trying to prove - food pricing policies through taxes or subsidies can improve health - is relatively untested. In fact, by their own standards the simulation studies reviewed were of "low" and "moderate" quality, and many did not account for "uncertainty" - or other factors - that taxes and subsidies can cause. For example, a tax on soda could lead to substitution of milkshakes and beer or other unintended consequences. We need better research before implementing government programs that may or may not improve public health."
The American Beverage Association commented that since 2000, full-calorie soda consumption has dropped by 12.5%. Consumers are switching to lower-calorie drinks, without "hiking the price".