Introducing taxes, subsidies or both: The effects of various food pricing strategies in a web-based supermarket randomized trial

ObjectiveFiscal policies may form a solution in improving dietary intake. This study aimed to examine the effectiveness of varying taxing and subsiding schemes to stimulate healthier food purchases.MethodsA randomized controlled trial with three levels of price reduction on healthy foods (no; 25%; 50%) × three levels of price increase on unhealthy foods (5%; 10%; 25%) factorial design was used. 150 participants were randomized into one of nine conditions and were asked to purchase groceries at a web-based supermarket. Data were collected in the Netherlands in January-February 2010 and analyzed using analysis of covariance.ResultsSubjects receiving 50% discount purchased significantly more healthy foods than subjects receiving no (mean difference = 6.62 items, p < 0.01) or 25% discount (mean difference = 4.87 items, p < 0.05). Moreover, these subjects purchased more vegetables (mean difference = 821 g; p < 0.05 compared to no discount). However, participants with the highest discount also purchased significantly more calories. No significant effects of the price increases on unhealthy foods were found.ConclusionPrice decreases are effective in stimulating healthy food purchases, but the proportion of healthy foods remains unaffected. Price increases up to 25% on unhealthier products do not significantly affect food purchases. Future studies are important to validate these results in real supermarkets and across different countries.

► We examine how taxes and subsidies on foods affect food purchases. ► We use a randomized controlled trial in a web-based supermarket. ► Subsidies are found to increase healthy food purchases, but also total calories. ► Taxes do not equilibrate this effect and do not significantly affect food purchases. ► Price measures have complex effects and form no easy answer in improving diet quality.