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Food Subsidies and Taxes Significantly Improve Dietary Choices

A new systematic review and meta-analysis finds that lowering the cost of healthful foods significantly increases their consumption, while raising the cost of unhealthful items significantly reduces their intake.

While everyone has a sense that food prices matter, the magnitude of impact of food taxes and subsidies on dietary intakes, and whether this varies by the food target, hasn't been clear. For the review, a team of researchers identified and pooled findings from a total of 30 interventional and longitudinal studies, including 11 that assessed the effect of higher prices (taxation) of unhealthful foods and 19 that assessed the effect of lower prices (subsidies) of healthful foods.

The findings were published in PLOS One.

"To date, evidence on effectiveness of fiscal policies on diet has mostly come from cross-sectional studies, which cannot infer causality. This is why we evaluated studies that examined the relationship between food price and diet over time," says cofirst author Ashkan Afshin, MD, former postdoctoral fellow at the Friedman School of Nutrition Science & Policy at Tufts University and now at the University of Washington. "Our results show how 10% to 50% changes in price of foods and beverages at checkout could influence consumers' purchasing behaviors over a relatively short period of time."

In the pooled analysis, each 10% decrease in price of fruits and vegetables increased their consumption by 14%, and each 10% decrease in price of other healthful foods increased their consumption by 16%. A change in price of fruits and vegetables was also associated with BMI: for every 10% price decrease, BMI declined by 0.04 kg/m2.

Conversely, each 10% price increase of sugar-sweetened beverages and unhealthful fast foods decreased their consumption by 7% and 3%, respectively. Every 10% price increase in unhealthful foods and drinks was associated with a trend toward lower BMI (per 10% price increase: -0.06 kg/m2), but this didn't achieve statistical significance.

"The global food system is causing a staggering toll on human health. And this is very costly, both in terms of real health care expenses and lost productivity," says senior author Dariush Mozaffarian, MD, DrPH, dean of the Friedman School. "Our findings suggest that subsidies and taxes are a highly effective tool for normalizing the price of foods toward their true societal costs. This will not only prevent disease but also reduce spiraling health care costs, which are causing tremendous strain on both private businesses and government budgets."

By merging findings from 23 interventional and seven prospective cohort studies, the researchers evaluated relationships between the change in the price of specific foods or beverages and the change in their intake. Studies evaluated people's reported intake or data on sales of foods and beverages. The study populations included children, adults, or both; and countries included the United States, the Netherlands, France, New Zealand, and South Africa. Price change interventions were conducted in various settings such as cafeterias, vending machines and supermarkets. The findings were centrally pooled in a meta-analysis.

— Source: Tufts University