Leiden environmental researchers have mapped the environmental footprint of different diets and revealed which population groups have the greatest impact through their food choices. Their findings show where efforts to make the food system more sustainable could make the greatest difference.
The greatest environmental gains are likely to come from looking more closely at eating patterns and the differences between population groups. This is shown by recent research from scientists at Leiden's Institute of Environmental Sciences (CML), Oxford University and Vienna University of Economics and Business, published on the cover of Nature Food. Averages, such as the average diet of a population, can hide where the greatest impacts on climate and nature actually occur. That is why Oliver Taherzadeh and his colleagues focus on the differences between groups.
Who has the largest food footprint?
Differences do not arise only in the way food is produced. People's diets also vary considerably. Most studies calculate the environmental impact of diets at the national level, even though eating habits can differ greatly within a single country. As a result, important differences between population groups often remain hidden.
Oliver Taherzadeh and his colleagues therefore developed MATILDA, a model that estimates the climate, land and water footprints, as well as the nutritional quality, of the diets of different population groups in 165 countries. The researchers considered factors such as age, sex, education level, and whether people live in urban or rural areas.
The diet of young, highly educated men living in urban areas has the greatest climate impact.
Their findings show that young, highly educated men living in urban areas have, on average, the largest climate impact through their diets. Rural women, by contrast, have the lowest average impact. Groups with a smaller environmental footprint tend to eat more plant-based foods, and are also associated with higher dietary quality.
Why does one meal have a bigger impact than another?
'The environmental footprint of diets can vary by more than five-fold between different socio-economic groups within the same country,' says Taherzadeh. While calorie intake plays a role, the composition of a diet is often more important. Diets with a high proportion of animal-based foods generally have a larger environmental footprint than mostly plant-based diets, as livestock production requires large amounts of land, water and feed. The impact of the same diet can also vary between countries, depending on how efficiently food is produced.
According to Hongyi Cai, co-lead author of the study, a key opportunity therefore lies in shifting towards more plant-rich diets, which can reduce environmental impacts while also offering higher dietary quality.
Where can we make the biggest difference?
Taherzadeh stresses that there is no single solution that works for everyone. People do not all start from the same point when it comes to making their diets more sustainable. Food consumption patterns and impacts are closely linked to factors such as health, income and where people live. By making these differences visible, Taherzadeh hopes to contribute to policies that better reflect the needs of different population groups. 'Our aim is to support food policy that is targeted and fair rather than one-size-fits-all.'
