Data from the systematic review, which was published today in the prestigious international journal, PLOS Medicine, also indicated that whilst taxes on food may hit poorer people harder than richer people the positive impact on health is likely to be relatively greater for low-income groups.
“This finding is particularly exciting because it suggests possible ways of reducing health inequalities through food pricing policies,” says Dr Eyles. “To avoid an overall detrimental financial impact on low income families and worsening food insecurity, though, a mixture of subsidies and taxes may be required.”
The team, comprising researchers from The University of Auckland and the University of Otago, Wellington, conducted a systematic review of simulation studies from the OECD countries which investigated the association between food pricing strategies, food consumption, and non-communicable diseases (NCDs).
For the first time in human history NCDs (such as cancer, cardiovascular diseases and diabetes) are killing more people than infectious diseases. One of the major risk factors for these diseases is an unhealthy diet, low in fruit and vegetables and high in salt and saturated fats.
In their combined analysis of 32 studies the authors estimated a modest 0.2 percent fall in energy intake from saturated fat for each ten percent price increase (or a two-percent fall with a 100-percent price increase).
“Whilst this is a modest change, when applied across a whole population the health impacts would add up,” says Dr Eyles, “since in New Zealand 13 percent of the energy we consume is from saturated fats.”
Likewise, the study estimated that a ten percent increase in the price of soft drinks could bring a decrease in consumption ranging from one to 24 percent.
In contrast it was found that lowering the price of fruit and vegetables by ten percent could likely increase consumption by between two and eight percent.
However, there was also evidence to suggest that subsidies on fruit and vegetables, as described above, may result in “compensatory purchasing”, with people who took advantage of the lower prices of fruit and vegetables then possibly choosing to buy less of other healthy foods (such as fish) and more of less healthy products (such as sugar).
Professor Tony Blakely from the University of Otago said that: “Based on modelling studies, taxes on carbonated drinks and saturated fats and subsidies on fruit and vegetables have the most promise as policies for improving health”.
The University of Auckland
“However, more research is needed to look closely at compensatory purchasing and at long-term health outcomes, especially for different socio-economic groups.”
Team members noted that the impact of any given food tax or subsidy is likely to differ from one country to another, depending on factors such as the type of tax system, the health status of the population and the social role of food.
“This research demonstrates promise for using taxes and subsidies to address current poor food environments,” says Dr Eyles, “but needs to both be subjected to more rigorous modelling studies, and debated politically.” She warns that robust evaluations must be carried out when governments are planning food pricing policies.
The literature review was funded by the Health Research Council of New Zealand as part of a research programme called “Population Interventions to Improve Nutrition and Physical Activity” directed by Associate Professor Ni Mhurchu.
The authors were Dr Helen Eyles and Associate Professor Cliona Ni Mhurchu from The University of Auckland, and Dr Nhung Nghiem and Professor Tony Blakely from the University of Otago, Wellington.