Menu composition must be 75% vegetarian to encourage sustainable plant-based food choices

Researchers from the University of Westminster have found that meat eaters are significantly more likely to choose vegetarian meals when they make up the majority of food offered. A menu had to be at least 75% vegetarian for this choice tipping point to occur.

People who usually eat meat shifted their choice to vegetarian food only when menus were 75% vegetarian, but not when 50% or 25% of items were vegetarian. Therefore, meat eaters can change their preferences when given enough vegetarian options to choose from, yet a large proportion of these options are needed to change fixed habits for consuming meat.

This new research involving Dr Beth Parkin at the University of Westminster and Dr Sophie Attwood from the World Resources Institute suggests that the food sector can have a significant impact in promoting sustainable food choices. The researchers argue that this can be achieved by changing how the choice is presented to the consumer without the need to consciously persuade individuals of the benefits of pro-environmental diets.

During the study, the researchers assessed how increasing the availability of vegetarian food in relation to meat impacts the choice of people who usually eat meat. These types of interventions are known as 'nudges', as they explore ways in which a decision can be designed to influence a desired behaviour. The study randomised participants to menus that contained different ratios of meat and vegetarian dishes to determine exactly how much meat availability is needed to promote sustainable choices. It is thought that availability may have increased vegetarian food choice by implicitly suggesting behavioral norms or by providing consumers with a wider range of desirable options.

The meat and dairy industries are large polluters accounting for approximately 25% of global emissions and if left unchallenged, the impact of the food system alone would prevent us from reaching targets laid out by the Paris agreement. Incremental changes to our diet can have a big impact on carbon emissions when applied at a large scale, resulting in a significant reduction in domestic GHG emissions.

This intervention shows the potential that the food service sector has in creating large scale shifts to encourage meat eaters to change their preferences. The findings provide practical instruction on what percentage of their food offerings should be vegetarian if they are to succeed in encouraging sustainable eating behaviours. If the food service industry are to decrease their carbon footprint, they need to act by providing far more plant-based items than currently on offer."

Dr Beth Parkin, lead author of the study, University of Westminster