Integration of environment and nutrition in life cycle assessment of food items: opportunities and challenges

Food systems have become increasingly efficient and technologically advanced in providing food products to meet the needs of the world’s growing population. However, providing healthy diets within environmental limits remains a key sustainability issue as food systems continue to over use
increasingly scarce natural resources while making a major contribution to environmental impacts such as climate change, water scarcity and biodiversity loss. At the same time, hundreds of millions of people suffer from chronic hunger or adult obesity, and healthy diets continue to be more expensive than energy- and nutrient-sufficient diets.

Many stakeholders are interested in the question of how to assess the environmental impacts of healthy diets, and in exploring solutions for minimizing trade-offs between nourishing populations and safeguarding the environment. Life cycle assessment (LCA) studies have an important role in
contributing to solutions because they evaluate the environmental impacts of different practices, products and systems, and they facilitate the exploration of benefits and trade-offs across multiple types of impacts. LCA studies of food items increasingly address nutritional as well as environmental aspects, and this requires consideration of additional methodological aspects.

The Food and Agriculture Organization of the United Nations (FAO) initiated a project to identify opportunities for further developing environmental and nutritional LCA methodology and building consensus about best practice, and to propose future research needs. The project involved 30
environmental and nutritional LCA researchers from 18 countries and ran between May and November 2021. The project focused on assessing food items as opposed to raw materials, meals and/or diets, and it is a step towards more comprehensive meal and dietary LCA studies.

A key issue concerns the intended purpose of an LCA study. This requires some consideration of the reason for the study, the intended application and the audience. Foods may be consumed for a variety of reasons including for their nutritional value, for enjoyment, and/or as a means of taking part in – or contributing to – socio-cultural functions. This report defines a nutritional LCA (nLCA) study as an LCA study where the provision of nutrient(s) is considered as either the main function or one of the main functions of a food item. nLCA studies should be undertaken by multidisciplinary teams involving nutritional and health scientists as well as environmental scientists.

At the outset, the goal and scope of an nLCA study should be carefully defined following the recommendations in this report, including:

• Undertake an nLCA when nutrients are and/or nutrition is relevant to the decision-maker and decision context (Chapter 3).

• Clearly identify the target audience and the target population for a study because different populations have different nutritional requirements, and this may influence the assessment of nutritional value (Chapter 5).

• Report the quantities of as many essential nutrients as possible (Chapters 5 and 6).

• Aim to provide information on the nutritional quality and/or health impacts in addition to nutrient quantities (Chapter 5, Chapter 6, Section 7.5.4).

• The system boundaries should include all stages of the product life cycle that affect nutritional value. The final processing, storage and/or preparation of food items may have a notable effect on their nutritional value, and this should be taken into consideration (including the potential
fortification of foods) (Chapter 5).

• Choose a modelling perspective (typically attributional or consequential) based on the relevance to the decision situation (Chapter 4).

The functional unit in an nLCA study can be defined in many ways (Chapter 6). These include: a quantity of one or more nutrients, a nutrient density value (calculated using a nutrient index), a quality-corrected quantity of nutrient(s), or another nutritional property (such as energy content). Alternatively, the functional unit could be a serving size. In all cases it should be relevant to the target population and its nutritional requirements. If possible, nutrients not included in the functional unit should be listed and discussed in the LCA report. Figure 5 and Figure 6 provide decision trees for guiding the choice of a functional unit in an nLCA study.

When assessing nutrition, consideration should be given to: accounting for nutritional value as well as nutrient quantities (for example, using nutrient indices), separate treatment of nutrients to encourage (e.g. calcium) and of nutrients to limit (e.g. sodium), and assessment of non-nutrients that contribute to nutrition (e.g. dietary fibre) (Chapter 5, Chapter 6).

In the impact assessment, research on the potential human health impacts of food items is at an early stage (Section 7.5.4). This report recommends using a nutrition impact category to account for the benefits or impacts of nutrition on human health (Section 8.1.1). Other particularly relevant
impact categories to consider in an nLCA of food items include (Chapter 7): climate change, water use, land use, eutrophication (related to fertilizer use), ecotoxicity (related to pesticide use), and other human health impacts (in particular, fine particulates from agricultural activities and indoor use of some stoves, pesticide exposure and residues in food, chemical migration into food from contact materials, persistent organic pollutants and metals that bioconcentrate in foods). Antibiotic resistance
is an emerging issue that requires consideration in the context of an LCA of food items (Section 7.7). Additional insights may be gained from integrating elements of the ecosystem services approach into an LCA (Section 7.6).
The project led to numerous recommendations about reporting nLCA results. To increase the usefulness of nLCA studies of food items for future meal and dietary studies, the results should be reported using a mass- or volume-based reference flow as well as a nutritional functional unit. The results should identify whether the approach is nutrient-based or whether it also includes nutritional aspects. And the reported result should discuss the limitations of the adopted approach, for example, not accounting for interactions with other food items in a meal or diet (i.e. food matrix and meal effects) (Chapter 5).

Some additional outstanding issues were identified in the project that require further attention (Chapter 8):

• definition of a minimum number of nutrients to be considered in an nLCA study, and whether this should be based on food groups (Chapter 6);

• treatment of nutrients to limit alongside, or separately from, encouraged nutrients (Chapter 6);

• use of nutrient indices to assess nutrition (Chapter 6);

• nutrition impact category methodology (Section 7.5.4), and further development of impact assessment methods for other impact categories (Chapter 7);

• how to represent nutritional changes that could occur during food storage, distribution and preparation if the system boundary for an nLCA study is set at a life cycle stage prior to consumption (Chapter 4);

• guidelines for use of an nLCA in different applications, including use of attributional and consequential modelling perspectives (Chapter 4);

• representation of data uncertainty and variability in nLCA studies (Chapter 4); and

•representative data for different regions (particularly developing countries) for the processing, distribution, retail, and consumption life cycle stages, and for food loss and waste (Chapter 4).

Finally, there is a need to extend nLCA methodology for the assessment of meals and diets, to consider further how to account for the multi-functionality of food in a sustainability framework, and to set nLCA studies within the context of environmental limits.

In summary, the constructive consensus-building process described in this report led to the identification of key outstanding issues and recommendations for the environmental and nutritional LCA of food items. The results provide a robust basis for future research to improve nLCA methodology
and apply it to identify solutions that minimize the trade-offs between nourishing populations and safeguarding the environment