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Publication at a glance
Type of publication: Scientific research article
Publisher: Scientific Reports (Springer Nature)
Authors: Ilkka Leinonen, Pasi Korkalo, Sanna Hietala, Kirsi Usva, Merja Saarinen
Commissioning body/funding: Aviagen
Geographical focus: Method development based predominantly on data from Finland
Year of publication: 2025
Target audience: Researchers, life cycle assessment (LCA) specialists, the food industry, sustainability experts and nutrition professionals
What is the study about?
The study addresses a fundamental question in the sustainability assessment of food: what function should a food perform for its environmental footprint to be meaningfully compared with that of other foods?
According to the authors, many existing comparisons are too limited because they are based on kilograms of product, energy content or crude protein content. While these metrics describe quantities, they do not fully capture the nutritional function of different foods.
The proposed method therefore extends the conventional life cycle assessment approach through what is known as system expansion. The focus is on the provision of essential and conditionally essential amino acids. At the same time, the method takes into account that many protein sources also provide energy and therefore fulfil an additional nutritional function.
Key findings
Amino acids instead of crude protein as the basis for comparison
The study defines the functional unit as 1% of the daily requirement of a 75-kilogram adult for all essential and conditionally essential amino acids. The decisive factor is therefore not the total amount of protein, but a food’s ability to provide a balanced amino acid profile.
The authors show that this can result in substantially different quantities of food being required, because protein sources vary in both protein content and amino acid composition.
Energy is included as an additional function
A key feature of the method is the treatment of energy content as another function of food. Many protein sources provide not only amino acids, but also fat or carbohydrates and therefore metabolically available energy.
To account for this multifunctionality, the model uses vegetable oil as a reference source of energy. Foods with a higher energy content are assumed to replace part of this energy source. The corresponding contribution is incorporated into the climate assessment through system expansion.
Results vary considerably by protein source
The case study compares, among others, beef, pork, poultry, dairy products, eggs, soya beans, peas, quinoa and almonds. The authors report substantial differences in the global warming potential of the protein sources examined.
While several plant-based protein sources show comparatively low values, some animal-based products have higher climate impacts. At the same time, the study makes clear that differences in results are not attributable solely to production systems, but also to amino acid profiles, energy content and the quantities of food required.
Implications for the development of nutritional LCA
Another focus of the study is the methodology itself. The authors argue that nutritional life cycle assessment (nLCA) approaches often do not fully capture the additional functions of foods. System expansion could offer a way of incorporating not only amino acids but also other nutritional functions into environmental assessments in a consistent manner.
Why is the publication worth reading?
The publication focuses on a fundamental methodological question that extends far beyond the comparison of individual protein sources: what exactly should a food be expected to provide within an environmental assessment?
Rather than presenting another ranking of food groups, the study proposes a way of integrating food functions more systematically into environmental analyses. In doing so, it critically examines existing nutritional LCA approaches and adds a perspective that considers amino acids and energy together. The study thus opens up a broader discussion about how future sustainability assessments along the protein value chain could be designed.
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* Transparency Notice: The publications featured on Foodtech Now! are selected and curated by the editorial team based on their relevance to the international protein industry. The analysis of the original publication and the preparation of this article were carried out with the support of artificial intelligence. This article is intended as an overview and does not replace reading the full original publication. The original source remains the authoritative reference for all content and statements.
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