While it’s relatively straightforward to compare the environmental footprint of producing apples and oranges (or even beef), these calculations become much trickier when the food contains multiple ingredients, and these make up the majority of what is sold in a typical grocery store. Until now, there were no good methods for determining the impact of these foods, but a team from Oxford recently published some of the first work to develop a sustainability metric for everything you eat. can find (edible) at his local grocer.
Beyond the approach’s sustainability estimates, the Oxford team then cross-checked their results against the standard nutritional metric NutriScore. With this, they discovered that there were many “win-wins” where foods were both sustainable and nutritious, although there were some notable exceptions. And, while the results aren’t too surprising, this method offers a new metric for consumers, retailers, and producers to make more informed choices.
One of the biggest obstacles to calculating the sustainability of multi-ingredient foods is that producers are rarely required to list the amount of each ingredient they put into a product. On the contrary, these details are often well-kept trade secrets.
But in some countries, like Ireland and the UK, at least some of this information is publicly available: the percentages of certain key ingredients. Researchers from the Livestock, Environment and People (LEAP) program and Oxford Population Health at the University of Oxford used these details (from the FooDB resource) to estimate percentages of ingredients in similar products, including more of 57,000 food items which almost all represent food and drink in UK and Irish supermarkets.
Once they had ingredient estimates, they used the HESTIA environmental database to calculate the impact of the full inventory. The team calculated an environmental score for each food that included a combined metric of four main impacts: greenhouse gas emissions, land use, water stress and the potential to cause toxic algal blooms. in downstream water bodies (i.e. eutrophication potential).
In a final step, they then cross-checked their sustainability results against the commonly used nutritional metric called NutriScore. This ranks foods based on “good” nutrients, such as protein, fiber, fruit/vegetable content, and healthy oils, as well as “bad” nutrients like calories, fat, salt, and sugar. added.
“We use NutriScore because it is quite widely used in many countries around the world and many researchers are familiar with the concept behind it,” said first author Michael Clark, from the University of Oxford. “The whole principle was developed to apply at the population level to achieve better health outcomes. It has been through a lot of validations and tests, and at the population level it has been very effective in this regard.
When the researchers tested their method against products with known ingredients, they found that it worked well. The resulting sustainability rankings were also broadly in line with what one would expect given the main ingredients of any item.
“Our results weren’t super surprising,” Clark said. “For at least the last decade, there has been growing evidence that some products are high impact – typically beef and mutton – and some products are low impact, such as plant-based foods. (with a few exceptions like chocolate and coffee).”
In general, meat, cheese and fish – and anything made with these ingredients – had the highest estimated impacts. Anything based on fruits, grains, or vegetables is ranked lower, as expected. When combined with NutriScore, there were clear win-win products that were nutritious and good for the environment, such as whole grain foods and 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 more harmful to the environment.
Work in progress
The research team hopes their work will be a starting point for a metric that could be used by consumers, producers and retailers to make more sustainable choices. Going forward, the biggest hurdle will still be the lack of ingredient transparency, which is not expected to improve anytime in the near future. Where and how ingredients are produced is another factor that can significantly alter impact, and one that is rarely disclosed.
“We hope this is the start of a longer journey and an opportunity to work together to develop something that is mutually beneficial,” Clark said. “The most exciting part is its application – we now have a mechanism to allow comparisons between a bunch of food products that people produce, sell or buy, and it allows them to make informed decisions about the impacts of those choices. ”
PNAS, 2022. DOI: 10.1073/pnas.2120584119
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