While it’s relatively easy to compare the environmental impact of producing apples to oranges (or even beef), these calculations become more complex when foods contain multiple ingredients—and these make up the majority of what’s sold in a typical grocery store. So far, there have been no good ways to quantify the impact of such foods, but a team at Oxford recently published some of the first work toward developing a sustainability scale for everything (edible) one might find at your local grocer.
Besides the approach’s sustainability ratings, the Oxford team went on to compare its results with the NutriScore standard nutrition scale. With this said, they found that there were many “common gains” where the foods were sustainable and nutritious – although there were some notable exceptions. And while the results weren’t too surprising, this method provides a new measure for consumers, retailers, and producers to make more informed choices.
One of the biggest hurdles to calculating the sustainability of multi-ingredient foods is that producers are rarely asked to specify how much of each ingredient they put in a product. Quite the contrary – these details are often kept so closely a trade secret.
But in some countries, such as Ireland and the United Kingdom, at least some of this information is publicly available: the percentages of some key components. Researchers at the University of Oxford’s Livestock, Environment, People (LEAP) and Population Health Program at Oxford University used this detail (from a FooDB resource) to estimate percentages of ingredients in similar products, including more than 57,000 food products that represent nearly all of the foods and beverages in supermarkets. British and Irish.
Once they had estimates of the ingredients, they used the HESTIA environmental database to calculate the impact of the entire stock. The team calculated the Environmental Score for each food which included a combined measure of four primary impacts — greenhouse gas emissions, land use, water stress, and potential for toxic algal blooms in downstream water bodies (ie, eutrophication potential).
As a final step, they reviewed their sustainability scores with a commonly used nutrition scale called NutriScore. It ranks this food based on its “good” nutrients, such as protein, fiber, fruit/vegetable content, and healthy oils, as well as “bad” nutrients like calories, fat, salt, and added sugar.
“We use NutriScore because it is fairly widely used in many countries around the world and many researchers are familiar with the concept behind it,” said first author Michael Clarke of the University of Oxford. “The whole hypothesis was developed for application at the population level to achieve better health outcomes. It has gone through a lot of validation and testing, and at the population level, it has been very effective at that.”
When the researchers tested their method against products with known ingredients, they found that it worked well. The resulting sustainability ratings were also broadly in line with what would be expected given the major components of an item.
“Our findings weren’t very surprising,” Clark said. “Over the past decade at least, there has been a growing amount of evidence to suggest that some commodities have high effects – generally beef and sheep – and some commodities have low effects, such as plant foods (with some exceptions such as chocolate and coffee).”
In general, meat, cheese, and fish – and anything made with these ingredients – had the highest estimated effects. Anything based on fruit, grains, or vegetables ranked lower, as expected. When combined with NutriScore, there were win-win products that were both nutritious and good for the environment – like whole grain products and their products. Potato chips also performed particularly well due to their high ‘vegetable’ content. Other foods, such as nuts, fish, and meat, were nutritious, but relatively tougher on the environment.
work in progress
The research team hopes their work will be a starting point for a scale that can be used by consumers, producers and retailers to make more sustainable choices. Going forward, the biggest hurdle will remain the lack of component transparency, which is unlikely to improve anytime in the near future. Where and how ingredients are produced is another factor that can drastically change the effect, and this is rarely revealed.
“We hope this is the start of a longer journey and an opportunity to work together to develop something mutually beneficial,” Clark said. “The most exciting part is its application – we now have a mechanism to allow comparisons to be made across a range of food products that people produce, sell or buy, and that allows them to make informed decisions about the effects of those choices.”
PNAS, 2022. DOI: 10.1073/pnas.2120584119