Estimating Food’s Environmental Impact

Analyses of the environmental impact of food tend to focus on basic commodities like “meat” or “nuts.” These analyses leave out most foods, which have multiple ingredients, meaning we don’t know the environmental impacts of the majority of the things we eat. 

Multiple-ingredient foods are harder to analyze for two reasons. First, retailers sell tens of thousands of products, which makes an analysis of each individual product time-consuming. Second, food companies consider how much of each ingredient they use a trade secret, so they won’t tell it to analysts. 

In this study, researchers developed an algorithm that uses publicly available information to estimate the environmental impact of multiple-ingredient foods. In the U.K. and Ireland, the government requires food companies to list ingredients on each product in decreasing order of abundance. About 10% of ingredients are characterizing ingredients (e.g., beef in beef lasagna). The U.K. and Ireland require food packaging to list what percentage of the food is a characterizing ingredient. From these facts, the algorithm figures out how much of each ingredient is in a given product. 

The researchers tested the algorithm on foods where it is known how much of each ingredient is in the product and found that the algorithm was sufficiently accurate. Then, they analyzed an additional 57,000 foods. 

Databases list the environmental impact of a food item from its beginning to its arrival in the store. The researchers took the results of the algorithm and used the databases to figure out the environmental impact of each food item. They looked at four variables: greenhouse gas emissions, scarcity-weighted water use, land use, and aquatic eutrophication potential (which describes the overfertilization of soil and water). The authors estimated the impact of a product per hundred grams of food. The algorithm overestimates the impact of certain foods that are usually eaten in small quantities, such as nuts. 

Because the databases offered an impact assessment for each ingredient, they don’t include the effects of making the product itself. For example, the algorithm includes estimates of the environmental impact of butter and flour, but not of baking a croissant. The researchers think that, if the latter impacts were included, the findings wouldn’t change much. Agricultural production makes up most of the environmental impact of food. However, the algorithm probably underestimates the impact of air-freighted produce and highly processed foods made of low-impact ingredients. Further, it’s difficult to know where an ingredient was sourced from. Usually, the most sustainable and least sustainable sources of an ingredient are pretty similar. However, in some cases, if the researchers knew the country origin of an ingredient, they would change their estimates. 

In general, food with low environmental impact on one axis also had low environmental impacts on other axes, although there were exceptions. The average product has a relatively low environmental impact compared to the products with the highest environmental impact, which suggests that cutting out a few harmful foods may substantially reduce a consumer’s environmental impact. 

The food category with the lowest estimated environmental impact is sugary drinks and other beverages, which are mostly water. Vegetables, snacks (e.g., chips and popcorn), some cereal grains, bread, and dairy and meat alternatives also had very low environmental impact. Many desserts (e.g., cakes, pies) and prepared foods had below-average environmental impact. Cheese, fish, pork, poultry, nuts, and sweet and savory spreads had above-average environmental impact. Beef and lamb had the highest environmental impact.  

In general, more environmentally-friendly foods are also more nutritious, but there are a lot of exceptions to this rule. Fruits, vegetables, salad, breakfast cereals, some breads, and meat alternatives tend to be both healthy and environmentally friendly. Cheese, chocolate, quiches, and savory pies tend to be neither healthy nor environmentally friendly. Nuts, fish, seafood, and some ready meals are conventionally considered healthy, but they aren’t environmentally friendly. Conversely, cakes, pies, sugary drinks, frozen desserts, and table sauces are environmentally friendly but not healthy.

Small changes have a big effect on environmental impact. For example, beef and lamb sausages had 240% higher impact than pork sausages, which had a 100% higher impact than chicken and turkey sausages, which had a 170% higher impact than vegan or vegetarian sausages. Lasagna showed a similar pattern. Low-nut pesto and cookies without chocolate also had lower environmental impacts. 

Armed with the results of this study, customers can make more informed choices about their diet while restaurants, grocery stores, and policy-makers may find it easier to promote more environmentally-conscious options. Furthermore, animal advocates can use this study to emphasize that cutting out the most harmful animal products will not only benefit animal welfare, but it will also make a difference for the planet. For people who want to gradually transition to a vegan diet, removing beef and lamb first is one impactful strategy to make a difference.