While it is relatively straightforward to compare the environmental footprint of producing apples versus oranges (or even beef), these calculations become much more complicated when foods contain multiple ingredients, and these make up the majority of what is sold in a grocery store. typical groceries. Until now, there have been no good methods for determining the impact of such foods, but an Oxford team recently published some of the early work to develop a sustainability metric for everything (edible) one might find in their local store.
Beyond the sustainability estimates of the approach, the Oxford team compared their results to the standard nutrition metric NutriScore. With this, they found that there were many “win-wins” where food was sustainable and nutritious, although there were some notable exceptions. And while the results weren’t too surprising, this method offers a new metric for consumers, retailers, and producers to make more informed decisions.
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. Quite the contrary: these details are often closely guarded trade secrets.
But in some countries, such as Ireland and the UK, at least some of this information is publicly available: the percentages of certain key ingredients. The researchers of Livestock, Environment and People Program (LEAP) other Oxford Population Health at Oxford University used these details (from the food database resource) to estimate the percentages of ingredients in similar products, including more than 57,000 food products representing almost all foods and drinks in supermarkets in the UK and Ireland.
Once they had estimates of the ingredients, they used the HESTIA environmental database to calculate the impact of the entire inventory. The team calculated an environmental score for each food item that included a combined metric for 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).
As a final step, they cross-checked their sustainability results with the commonly used nutrition metric called NutriScore. This classifies foods based on “good” nutrients like protein, fiber, fruit/vegetable content, and healthy oils, as well as “bad” nutrients like calories, fat, salt, and added sugar.
“We use the NutriScore because it is widely used in many countries around the world and many researchers are familiar with the concept behind it,” said first author Michael Clark of the University of Oxford. “The entire premise was developed to be applied at the population level for better health outcomes. It’s been through a lot of validation and testing, and on a population level, it’s been very effective at that.”
When the researchers tested their method on products with known ingredients, they found that it worked well. The resulting sustainability rankings were also largely consistent with what would be expected given the main ingredients of any item.
“Our findings weren’t very surprising,” Clark said. “Over at least the last decade, an increasing amount of evidence has emerged indicating that certain commodities have a high impact, typically beef and lamb, and certain commodities have a low impact, such as plant-based foods. (with some 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 ranked lower, as expected. When combined with the NutriScore, there were clear win-win products that were nutritious and good for the environment, such as whole grain foods and products. French fries 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 that their work will be a starting point for a metric that consumers, producers and retailers can use to make more sustainable decisions. Going forward, the biggest hurdle will continue to be a lack of ingredient transparency, which is unlikely to improve in the near future. Where and how ingredients are produced is another factor that can significantly change impact and is rarely disclosed.
“We hope this is the beginning 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 that allows comparisons to be made between a series of food products that people produce, sell or buy, and this allows them to make informed decisions about the impacts of these choices. .”
PNAS, 2022. DOI: 10.1073/pnas.2120584119