A study has revealed that a new way of calculating the environmental footprint of foodstuffs leaves the impacts of animal-based products like dairy beef almost half of what they were before.
The study, which was carried out by Rothamsted Research, took a measure of protein quality called the Digestible Indispensable Amino Acid Score (DIAAS) and used it to create adjusted environmental footprint metrics for a variety of foods.
When researchers used this new method of calculating the environmental footprints of food, dairy beef fell, while impacts associated with the likes of wheat bread increased by almost 60%.
The authors of the study said that the full nutritional value of foodstuffs needs to be considered when calculating the environmental impacts of different foods.
Lead author of the study, Dr. Graham McAuliffe, said it highlights the need for both nutritional and environmental sciences to be taken into account when assessing the impact of food production on human and environmental health.
“Simple ‘mass-based’ (nutrient content rather than quality) comparison of food items’ sustainability is not sufficient to provide policymakers and stakeholders with transparent and useful information on how to reduce their environmental impacts across agri-food supply chains,” he said. .
“Food items are rarely consumed in isolation, and therefore one of the major recommendations we urge future nutritionally-focused sustainability assessors to consider is the complementarity of food at, for instance, the meal level or multi-meal level.”
The environmental footprints of certain foodstuffs, calculated per unit of protein produced, risk misinforming food stakeholders and consumers, according to Rothamsted.
The research team explained that the quantity of protein in a product does not represent the quality of the protein, which is affected by factors, eg, some food items (typically plant-based products) contain other factors which can inhibit or restrict nutrient uptake.
The researchers also stressed that some amino acids are not produced directly from humans and must come from our dietary sources. As well as this, they said the digestibility of different amino acids in the human gut is highly variable.
The team used the DIAAS score to represent how digestible a food item’s amino acids are. This was applied to four animal-based foods (dairy beef, cheese, eggs, and pork) and four plant-based protein sources (nuts, peas, tofu, and wheat).
The animal-based products scored more than 100% DIAAS due to their highly digestible structure and lack of inhibitory compound.
Tofu had a DIAAS of 105%, while the three other plant-based protein sources scored under 100%, with wheat scoring particularly poorly (43%), according to the researchers.
A healthy average human would need to consume much more low-DIAAS products to achieve the same protein benefit compared with high-DIAAS products.
This would lead to more production and associated environmental impact to reach the same level of recommended intake, the team explained.