Integrating nutrional quality into environmental impact assessment and communication - a product group approach

Life Cycle Assessment (LCA) is a commonly used standardised method for measuring the environmental impacts of products and services during their life cycle. As the name suggests, LCA takes into account all stages of the life cycle, from raw material production to waste disposal. The most commonly measured environmental impacts are the climate impacts, or carbon footprint. Life cycle assessment allows comparisons between different products and is therefore a commonly used method for assessing, for example, potential emission reductions. 

In life cycle assessment, the comparison is based on the functional unit, which in practice means the unit per which the environmental impacts of products are calculated. Traditionally, the functional unit for food products has been the kilogram of product. However, the fundamental function of food is to provide nutrition, and in recent years methods have been developed to use nutrient content as a functional unit. In this way, the environmental impact of a food product is related to its nutritional quality. The Natural Resources Institute has already developed this methodology in previous projects and at the end of 2021 the Food and Agriculture Organization of the United Nations (FAO) published general guidance on methods to link nutrition to life cycle assessments. 

The NEPGa project developed functional unit nutrient indices for different product groups. The product group approach is based on the idea that consumers consume different products in different ways and that different product groups play different roles in nutrient intakes from the diet. This allows us to compare products used in the same way on the basis of the nutrients relevant to those products. 

For this project, the product grouping is based on the plate model of the Nutrition Recommendations. The plate-based grouping allows us to compare products that can be used as substitutes for each other, such as meat and plant-based protein sources.

In line with the plate-based product grouping, we have created separate indices for vegetables, carbohydrate sources, protein sources and beverages. In addition to these, there are categories such as soups or casseroles, which are not represented in the current plate model and which combine several product groups. The development of the product category indices has been published as scientific articles (links here and here). Both validated using principal component analysis.

One method of integrating nutrition into life cycle assessment is to use nutrient indices as a functional unit. A nutrient index describes the average nutrient content in relation to the recommended intake of nutrients and thus allows more nutrients to be included in a single figure. The index is calculated using the following formula. 

Index = (intake/recommendation1+intake/recommendation2+...)*100/number of nutrients in the index

The index can include all possible nutrients or alternatively the index can be compiled by selecting only certain nutrients. As the NEPGa project is looking at product groups according to national nutrition recommendations, we have developed an index for each product group that includes only the nutrients relevant to that product group.