Why is comparing foods on their climate impact not enough?
We eat food for many different reasons; from celebrating special occasions to comfort eating our way through the winter blues. At the most basic level, we eat food for energy, nutrition and sustenance. The thing is, not all foods are created equal; we get much more energy and nutrition out of some foods than others. There’s a big difference between a rice cake and a beef burger, so any food ranking that looks exclusively at the climate impact of food products, misses out on the key values of the food itself.
In general, there’s a good overlap between foods that are nutritious and foods that have a low climate impact (seasonal fruit and vegetables, for example), but it’s not always the case!
We can’t run the risk of people becoming nutrient deficient in an attempt to reduce their climate impact, so right from the beginning we’ve been exploring different ways to combine climate impact and nutrition into one easy, sustainability score.
Here’s our progress so far:
Phase 1: The Food Unit
The first rating system that we’ve implemented is known as the Food Unit. It combines the climate impact of a food product with the amount of calories, protein, fats, dry matter and water content of the food. The calories tell us how much energy is in the food, proteins and fats are important macronutrients, and the ratio of dry matter and water content in a food gives an indication as to how full you’ll feel after eating it. This rating has been pioneered by our Swiss data science partners Eaternity, and is a good first attempt to combine the nutrition and energy provided by a food with its climate impact. The final score is converted into a five star rating which is assigned to each product, the more stars the better. For your basket score, we calculate the average Food Unit for each of the products you purchased and show that as a star rating too.
With growing usage we’ve found some interesting anomalies. For example, since the Food Unit doesn’t consider the micronutrients present in a food, vegetables don’t get the full credit for how good they really are. Foods that are calorie dense do phenomenally well, with foods like sugar and marshmallows doing better than we’d expect. On the other hand, drinks like tea and coffee get a terrible score because they are both low in calories, protein and fats.
Phase 2: The Nutrient Density per Climate Impact Index
The next step after the Food Unit is to adopt a Nutrient Density per Climate Impact Index for our scoring. Such an index measures the quantity of 11 (or 9) essential nutrients in a food against the recommended daily allowance of those nutrients and compares those quantities to that of the 3 most harmful nutrients when consumed in excess; saturated fats, refined sugar, and sodium.
This ratio of the good to the bad is then combined with the product’s greenhouse gas emissions. This is also translated into a five star rating, showing us how to get the most nutritious food for the lowest climate impact.
The benefits of using the Nutrient Density per Climate Impact index instead of the Food Unit is that it accounts for micronutrients and the negative effects of consuming too much fat, salt, and sugar. The main shortcoming compared to the Food Unit is that it does not account for the energy provided by the food.
The difference between “healthy” and “nutritious”
What’s important to note is that looking at nutrition alone isn’t enough to say whether a food is healthy or not. For example, studies link processed meats to increased likelihood of bowel cancer, but we can’t yet account for this in scoring system that we have in place. We can’t say yet that the Evocco score guarantees you the healthiest food for the lowest climate impact, but what we can say is that we help you find the most nutritious food for the lowest climate impact.