Meta-analysis of consumers' willingness to pay for sustainable food products.

There is a continuous increase in the number of studies dealing with consumers' willingness to pay (WTP) price premiums for sustainable food products. This research focused on a broad area of sustainable food products, including different sustainable attributes using a meta-analysis of 80 worldwide studies. The publication bias was verified using the funnel plot and Egger's test. In addition, the subgroup analysis and meta-regression were applied to classify the source of heterogeneity. The results suggest that the overall WTP premium for sustainability (in percentage terms) is 29.5% on average. Furthermore, gender, region, sustainable attributes and food categories influence the average WTP estimates and their heterogeneity. Results also indicate that the WTP estimate conducted by hypothetical approach (choice experiment and contingent valuation method) is higher than non-hypothetical one due to hypothetical bias. In addition, the WTP estimate from the CVM is higher than that from the CE. Additionally, the WTP value of organic attribute is higher than the other sustainable attributes. The subgroup analysis indicates that the fruit &vegetable category has the highest WTP estimate while the seafood receives the lowest one. Results also highlight that Asian WTP estimates, in percentage terms, are higher than those obtained in North America and similar to those from Europe. In addition, positive WTP estimates are shown independent of the food categories, region or methods, denoting the presence of great market potential for sustainable products worldwide. The findings of this research can be used as a guide by food producers, marketers and policymakers when making decisions related to the sustainability of food products.