Pioneering research has uncovered a cunning way to curry favour with diners' food choices, so they're more likely to select meals which have a much lower carbon footprint and reduced fat content.
The study, led by the University of Bristol in the UK and published today in the journal Nature Food, showed the carbon footprint of canteen diners' weekly meal choices dropped overall by around a third – and saturated fat levels also significantly fell – when selecting from a cleverly reshuffled weekly set menu. Best of all, diners didn't seem to realise the difference.
Lead author Dr Annika Flynn, Senior Research Associate at the University of Bristol, said: "Improving people's dietary habits to deliver meaningful health and environmental benefits is a meaty challenge. So the scale of benefits generated by our relatively simple intervention of weekly menu manipulation, which didn't change the actual dishes or recipes themselves and seemed to go unnoticed, were really surprising.
"This sneaky technique could be a game-changer in many different kitchen menu settings, especially given people's growing appetite to make healthier decisions and the increased drive to reduce carbon emissions globally."
Changing how people can decide, restricting the number of choices available – for example the legal minimum age to buy alcohol – or disincentivising a particular option – such as the 'sugar tax' – are all proven techniques used by governments to drive behaviour change. Although influencing what people opt to eat is no mean feat, the researchers reckon there are rewards to be reaped among the 42% of UK workers who report eating at a canteen, as well as the millions of children and young people served meals daily at schools and universities.
Chiefly, the researchers wanted to test the theory that specific health and environmental benefits can be delivered by merely rearranging the meal options on a weekly set menu, based on consumer preferences and meal attributes. That marked the start of a project called SNEAK (Sustainable Nutrition, Environment, and Agriculture, without Consumer Knowledge), supported by the UK Research and Innovation (UKRI) Transforming UK Food Systems for Healthy People and a Healthy Environment Programme.
They teamed up with the University's Catering Department, which is at the forefront of introducing healthy, more sustainable food options in the higher education sector. For starters, they used computational mathematics to number crunch data on the popularity of different meals. Using this intel they then reorganised the weekly menu, swapping meals across the week to change the 'competition' between dishes served each day at a catered halls of residence.
Co-author Jeff Brunstrom, Professor of Experimental Psychology at the University of Bristol, explained: "In a nutshell, we rotated two weekly menus comprising three different evening meal choices each weekday. Typically this would generate 1.4 million menu combinations, but we slashed this by around 90% to 113,400 combinations after simply stipulating one of the meal options must be vegan to cater for diverse needs by students. But our optimised menu featured the same 15 dishes as the original, just reorganised on different days to boost uptake of the more sustainable, healthier options."
One of the weekly menus was shown to reduce the overall carbon footprint by 31.4% and saturated fat intake by 11.3%, while the other lowered the overall carbon footprint by 30% and saturated fat intake by 1.4% across some 300 diners.
Dr Flynn added: "Since diners can only choose one evening meal per day, we found it is best to cluster the meals with a high carbon footprint and saturated fat content, such as lasagne and chicken Kiev, on the same day so these more popular options compete against each other. That means greener options – like lentil chilli and cauliflower curry – are more likely to be chosen across the week. The net effect is that peoples' total weekly carbon footprint and saturated fat intake is reduced."
Findings indicated diner satisfaction levels were largely unaffected by the change. The study also modelled the potential for other notable nutritional and environmental benefits from making the menu switch. For instance, some menu combinations had the potential to increase fibre intake by 69.2% and salt intake by 14.1%. Land use and possible over-enrichment of water and soil might also be cut by around a third (31.7% and 33% respectively).
Co-author Alex Sim, Development Chef at the University of Bristol, said: "Over the years students have become increasingly interested in the environmental impact and healthiness of their meals, so they tend to be very receptive to making changes and trying new dishes.
"While there will always be clear favourites, like chicken Kiev and lasagne, vegan options which generally have a smaller carbon footprint, are also proving very popular. Structuring menus to help further promote these choices is a clear win-win. We work hard to make these options really flavourful and nutritious, so it's great to see them going down so well with students."
The University of Bristol is making significant changes to reduce carbon emissions and is committed to becoming a net zero campus. For instance, it was the first university in the world to achieve institutional Green Labs Certification for each of its 990 laboratories, and its Source catering provider now shows the carbon footprint on all menus.
The research was funded by a UK Research and Innovation (UKRI) Strategic Priorities Fund (SPF) called Transforming UK Food Systems and is also supported by the National Institute for Health and Care Research (NIHR) Bristol Biomedical Research Centre (Bristol BRC).
Professor Richard Martin, Associate Pro Vice-Chancellor for Research and Innovation at the University of Bristol, said: "Human dietary habits are generating an unsustainable burden on healthcare systems and environmental sustainability globally. So these results are extremely exciting because they demonstrate how simply changing the competition structure within weekly set menus can help steer millions of people towards making choices which have significantly lower carbon emissions and are healthier too.
"Thanks to the excellent work of our talented researchers and catering experts, we're leading the field in offering students enticing, well-balanced meals that are also kinder to the environment – a cause they really care about. We're already scaling this up by sharing our learnings and innovative recipes with the catering teams of other universities across the country. There is also the wider potential to apply this technique in other settings, like schools, hospitals, care homes, and workplace canteens. The collective impact could be huge, and provides exciting food for thought about how a fresh approach to menu design might play a tangible part in helping address a pressing global challenge now and in future years."
