Comparing the environmental cost of foods: Nutritional LCAs

The environmental impact of a food, be that carbon footprint, water use, land use or some other factor, can be estimated by life cycle analysis (LCA). With the environmental impact of food an increasingly important consideration for many consumers, industry and policymakers, the FAO have recently published a report on the challenges and opportunities of nutritional LCAs – those that attempt to capture the nutritional value of food alongside its environmental impact.

LCAs are strongest when used to identify hotspots or areas for improvement within the supply chain for a single item. They can be used to answer industry questions like: where should we act first to lower the footprint of our product? They can also be used in comparisons between two otherwise identical products for consumers: which one should I buy? However, challenges arise when LCAs are used to compare the impacts of very different products.

Take Energy Rating labels on electrical appliances as an example. Analogous to LCAs, these are an indication of the relative energy usage of a particular model compared with other appliances of the same type. These are useful for comparing two refrigerators, but do not really help when comparing refrigerators with freezers. They are even less useful when comparing a refrigerator with a washing machine: the appliances have completely different functions, and a purchaser would be unlikely to use them to choose which of the two to take home.

Even within the category of refrigerators, ratings become less relevant when comparing different size models, as they provide a different level of service. Without considering the service or benefit provided by the product we do not have a fair basis on which to compare the footprint or cost of providing that service.

The same problem exists when comparing foods. When we look at the footprint of food products and start making comparisons, we need to be clear on the service or benefit being provided by the products to ensure we are making a valid comparison. However, the service provided by a food item depends on the purpose for which it is consumed.

Food is consumed for a variety of reasons: as a source of nutrition, for sensory experience or pleasure, or for social and cultural purposes. Accounting for these different purposes is not straightforward. For example, from a nutritional perspective, alcoholic beverages provide very little benefit, but many consumers may still place high value on their sensory or social purposes.

The FAO report focuses on nutrition, rather than the other services provided by food, and looks at how nutritional information can be combined with environmental impact data.

One approach is to try and bring together the “benefit” and “cost” into a single analysis: the development of a nutritional LCA (nLCA), a life cycle analysis that includes nutrition.

There are two different methods by which this can be done:

  • As part of the definition of the functional unit (e.g., land use per 100 kcal)
  • As part of the human impact assessment, what is often thought of as the cost side of the analysis (e.g., likely impact on human health)

Neither of these approaches is easy.

Shifting functional units

Often, an LCA uses mass as the functional unit. For example, if considering the water use needed to grow rice, an LCA might report results as “litres of water used per kg of rice”. In this case, the functional unit is “1 kg of rice”.

Putting nutrition into the functional unit moves away from just using mass. In the simplest form, this may be evaluating a set of foods based on the amount of a particular nutrient they contain. Protein is often used for this purpose. Our rice example would then change to “litres of water used per kg protein in rice”.

However, protein is not a single nutrient needed by the body, but rather a collection of amino acids, which are the essential nutrients. Not all proteins are created equal, having both different concentrations of these amino acids and varying in their digestibility. Rice protein is therefore different to soy protein, for example. Thus, comparing water use per kg protein does not capture this information. Sophisticated methods that include protein quality exist, but are challenging and rarely used.

Most food items provide more than one nutrient, and we need a broad range of nutrients to remain healthy. The DELTA Model® estimates the ability of the global food system to supply a basket of 29 nutrients, and would include more given suitable data. Evaluating a food item based on only one target nutrient misses this complexity.

An alternative to selection of a single nutrient as the functional unit is to use a basket of nutrients to create some form of nutrient reference score. The intention of this score would be to provide a more “balanced” view of the nutrition provided by foods. However, what nutrients should make up this score? Do they all have equal weighting? Or are some more important than others? And how does this relate to the needs of an individual? The scientific literature contains many different suggestions, each with their strengths and weaknesses. Each is at risk of introducing some form of bias into the assessment.

Another important consideration is portion size. Once we move away from a functional unit based on mass, we lose some of the context around the amount of food that needs to be consumed to deliver a particular nutrient or group of nutrients, and how that relates to the size of a normal serving. Functional units “per serving” have also been explored, but face the same problems as mass based units.

Bringing human health into the assessment

The alternative approach is to leave the functional unit as the mass of the food item and build the nutritional assessment into the impact side of the LCA. This requires having data on the expected impact of consuming a food for human nutrition or health. The main approach that has been considered to date uses epidemiological data on diets, health, and mortality. This is usually of the kind captured in the Global Burden of Disease (GBD) study, which calculates statistical links between consumption of food groups and expected lifespan or quality of life.

Unfortunately, this data is limited to comparatively coarse effects. The GBD study reports statistical measures for 15 health aspects related to diet and 3 related to nutrient deficiency. The statistical associations are the result of a complex analysis that attempts to isolate the impact of individual food factors on overall outcomes. Changes in assumptions used in the analysis between the 2017 and 2019 data sets resulted in significant changes in the apparent impact of several food groups. These have been highlighted in a recent letter to The Lancet, and would have a major effect on any nLCA employing this data.

In general, the benefits of consumption of food or nutrients follow a curve. Initially there is a positive impact on health, with increasing consumption providing nutrients essential to bodily functions and growth. This benefit is reduced once daily requirements are met, and, if consumption continues to increase, may eventually have negative health outcomes.

This is illustrated with the energy content of diets: eating insufficient calories leads to wasting, but eating too many leads to obesity and a range of related health conditions, and just how much is too few or too many depends upon the need of the individual. Sodium is another example: a diet deficient in sodium can have serious health consequences. However, many diets contain a considerable excess of sodium, carrying health risks for many individuals.

Putting food and nutrients in context

Food items are consumed as part of meals and diets, and it is at this level that we need to apply considerations of nutritional sufficiency. The relative nutritional benefit of consuming a food item varies based on the dietary context of the individual. For example, the protein or amino acid content of a food item may be of limited value in a diet that is otherwise oversupplied with this nutrient, but of immense value in a diet that is deficient.

Within the DELTA Model we have implemented a simple nutrient contribution measure for food items. This is based on the sum of the relative contribution the food item makes to each of the nutrients captured in the model. As such, it gives a higher weighting to nutrients that have low global availability and a lower weighting to nutrients that are abundant.

For example, the default 2018 DELTA Model scenario has a 34% deficiency for calcium against global requirements (achieving 66% of target), whereas phosphorous has a 150% excess (250% of target). Thus, a food that provides 33% of the daily target for calcium gets a score of 0.5, whereas 33% of the daily target of potassium scores only 0.13 – approximately ¼ the importance. A similar approach has recently been published for the individual dietary context.

The right use of nLCA

The challenges described above stem from trying to compare refrigerators with washing machines, and lead us to the fact that nutrition does not easily collapse into a single score.

The scope of comparisons, or the grouping of foods into groups becomes important. If food items are grouped with others that provide or purport to provide similar nutritional benefits, we can make more realistic comparisons that better reflect the real choices facing us.

As an example, we might compare the nutritional LCA of milk with that of a plant beverage and use a nutritional functional unit that reflects the role of these items within the overall diet. Milk products make a significant contribution to the global supply of calcium, phosphorous, and potassium, six indispensable amino acids, dietary fat, overall protein, and vitamins A, B2, B5, and B12. A nutritional functional unit could be designed that reflects this nutritional value to enable us to compare milks and milk-alternatives when consumed as a source of nutrients. However, this same approach would not necessarily be appropriate if the purpose of the product was simply to whiten a cup of coffee. The intended service or benefit of foods must be understood when deciding how to compare costs.

Whilst the concept of a universal nutritional LCA that provides all the information necessary to support a wide range of decisions is attractive in its apparent simplicity, the reality is that nutrition and environmental impacts are too complex, and too important, to be reduced to a single number.

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“Local” food and sustainability

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Local food supply chains are often touted as more sustainable than international food trade. A recent review aimed at decision makers in the food system has emphasised that this is not a rule of thumb.

The review provides a clear explanation for why the purchase and consumption of food produced locally is not necessarily more sustainable than food that has travelled longer distances.  For example, a food product’s carbon footprint is determined much more by land use and production efficiencies than by the distance it has travelled.

Transport-related emissions account for only 5-6% of global food system emissions. As exemplified by the authors: “cargo ships or trains can exploit economies of scale and be relatively less polluting over longer distances than small trucks over shorter distances.  Similarly, if consumers visit individual local producers, their carbon emissions can be greater than the emissions from the systems of large-scale suppliers.” 

The authors provide strong arguments for the need for strategic diversification of food supply via international trade to create food security. The food demands of less than one-third of the global population could be met from local crop production, even with dietary adjustment, reductions of yield gaps and reduced food waste. Depending upon location, 26-64% of the population could not meet their demands for specific crops within a radius of 1000 km.  This distance could become even larger if all essential nutrient requirements were considered. Less than 50% of people worldwide could sustain their existing dietary compositions from the continents they live in. 

The article also draws a distinction between “local” based on distance, and “short” based on number of actors in the supply chain. Both of these qualities have an impact on sustainability. Purchase of local food can provide localised economic and social benefits, but there is little evidence that localised production systems make food more affordable for consumers.  The fact that “local” and “sustainable” are not equivalent when it comes to food is accepted in the scientific field, but is still a widely leveraged concept for retail and consumers.

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Glossary

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Minor links between agricultural subsidies and greenhouse gas emissions

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The impact of agricultural subsidies on climate is challenging to quantify and few such studies exist. In a recent article in Nature Communications, this relationship and its consequences have been examined.

Between 2017 and 2019 global agriculture received over US$553 billion per year in subsidies and support. This equated to approximately 10% of total farm revenue for the six commodity groups examined in this article (rice, other cereals, milk, ruminant meat, pig meat, and poultry meat). The authors coupled economic and production modelling to estimate the difference between current greenhouse gas (GHG) emissions and their state if agricultural support were removed.

The paper demonstrated that, contrary to popular commentary, agricultural subsidies have a very limited impact on GHG emissions. In fact, subsidies had a net negative 1.7% impact on GHG emissions from agriculture in the study period and gave a net 1.1% increase in farm production.

Assuming global emissions from agriculture to be approximately 25% of all emissions, this translates to less than a 0.5% impact on total global emissions. This was the result of incentivising production away from high emission-intensity, low production countries to low emission-intensity, high production countries.

The paper would be strengthened by consideration of the impact of land use change on soil carbon sequestration, which the authors recognise and recommend for future research.  It also does not consider the other environmental impacts of agriculture, such as water use, and particularly does not attempt to consider how nutrition and diets would be impacted by changes to subsidies. 

The authors recommend that for the purposes of reducing climate impact, use of large sums of agricultural subsidies could be better spent on R&D to improve agricultural production and simultaneously reduce emissions. However, the current purpose of subsidies is not to reduce emissions, but is based on political and economic considerations.

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The dietary trio of healthy, nutritious and climate-friendly

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A recent study and accompanying editorial have compared dietary nutrient density and diet-related greenhouse gas emissions to understand whether individuals consuming more nutritious diets with lower carbon footprints have a longer lifespan than others.

The short editorial highlights some of the issues in interpreting data for the relationships between mortality and food. Nutrient density, as measured here, can be assessed through multiple metrics. Similarly, climate impact can be measured in many ways, here via greenhouse gas emissions in CO2-equivalents.

Although the impact of nutrition on death rate is an important consideration in assessing the impact of diets on health, it is limited and does not account for broader lifestyle impacts on mortality. 

Similarly, although climate impact is an important consideration in assessing the impact of diet on the environment, land, water, and fertiliser use (among other factors) must also be considered in assessments of the environmental efficiency of diets.

Within these limitations the study found several interesting associations, with notable differences between women and men. 

In the female cohort, mortality was 13% lower for those consuming diets with a high nutrient density and a low climate impact compared to those on low nutrient density and high climate impact diets. However, the same reduction in mortality was found for those consuming diets with a high nutrient density and high climate impact, indicating that nutrient density was the most important factor in the reduced mortality rate.

For men, mortality was 11% higher for diets having a low nutrient density and low climate impact compared to diets having a low nutrient density and high climate impact. It was suggested that this was due to sugar content: sugar has a small climate impact, but a clear negative impact on health when overconsumed.

The editorial makes some useful suggestions for how improvements can be made to such studies, such as considering food intake rather than reducing the assessment to individual nutrients. These results emphasise that climate-friendly diets are not always healthy, and vice versa, but that healthy, climate-positive diets can be achieved.

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Glossary

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Linking agricultural conditions to childhood undernutrition

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A study of infant malnutrition in the West African country of Burkina Faso has established a link between its prevalence and local agricultural conditions.

Climatic conditions play a major role in determining the performance of agricultural land and food production, with local and seasonal variation. The availability of food is an output of this performance, with clear implications for nutrition. In this study, the authors combined household nutrition surveys, malnutrition data and a remotely sensed drought indicator to investigate associations between agricultural conditions and malnutrition.

The Water Requirement Satisfaction Index (WRSI) combines precipitation, temperature, humidity, wind, and solar radiation data to ascertain whether the water needs of an area of cropland are being met. WRSI is a useful risk management tool employed in many parts of the world to study drought and crop yield.

Localised WRSI data was combined with household survey data from Burkina Faso, focusing on 1,721 children aged between 6 months and 2 years old. Around a third of the children were malnourished, as were a quarter of their mothers. Just 15% of the infants had achieved the WHO’s minimum dietary diversity standard over the 24 hours before the survey.

As found by previous studies, undernourished mothers were more likely to have undernourished children in their care. Low dietary diversity, recent diarrhoea, and lower education level of mothers were also associated with malnutrition.

The novel finding of this research was the association between higher WRSI values and reduced chances of malnutrition. These higher values, indicative of regions where the water needs of agricultural production were being met, were also associated with increased infant dietary diversity.

While better agricultural conditions could reasonably be expected to tally with greater food availability and thus reduced rates of malnutrition, studies that consider the interactions between agricultural production due to local climate and nutritional outcomes are rare. These results emphasise the interconnections in our food system – in this case, between rainfall and nutrient adequacy – that have a profound effect on the outcomes for people.

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Commentary on nutritional LCAs

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Dr Bradley Ridoutt, Principal Research Scientist at Australia’s CSIRO and agricultural sustainability researcher, has recently published a commentary on the challenges and opportunities for combining nutritional information with the environmental impacts of food.

Recent years have seen increased efforts to compare the environmental impacts via life cycle analysis (LCA) of food to lead diets and production down more environmentally sustainable paths. Dr Ridoutt highlights that, as yet, no universal definition or best practice for nutritional LCA exist, leading to discussion (including by the FAO) on what the best approach might be.

In a previous article, we discussed the use of LCA in food sustainability research. The main limitations of the nutritional LCA approach were reiterated in the commentary article. A key question remains: what is the function of food? And thus, how should we compare foods?

As stated by Dr Ridoutt, “Foods contain a variety of nutrients, and a healthy diet requires a variety of foods.” Defining an appropriate way to compare the worth of different foods is challenging, which makes incorporating this with environmental impact (fraught with its own challenges of what factors to include), nearly impossible. Dr Ridoutt notes that the further inclusion of the health outcomes of food, often contested, adds to this challenge.

A key quote in the article is “…wrapping environmental LCA results together with nutritional epidemiological findings would appear unlikely to inform wise decision-making and will most likely only benefit individuals and organisations with a social or commercial agenda to promote.” The author concludes that only through separate reporting of the nutritional and environmental impacts of food can trade-offs be identified and assessed. Given that the relative importance of these two impact categories will vary between individual perspectives, this area seems likely to be highly discussed for the foreseeable future.

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Glossary

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Evidence for Sustainable Food Systems at Three Scales

The future of the food system is a major topic of conversation with various voices advocating the need for a range of changes, with some being quite radical. Historically the focus on the global food system was on providing enough nutrition for those in most need. This has transitioned to many advocating a need for the food system to change to address issues that are a consequence of wider human activities.

When we talk about the food system what are we referring to? What are we talking about changing? And how do we understand the potential impact of changes? This Thought for Food considers three different scales at which we can consider questions around the food system and the work the Sustainable Nutrition Initiative (SNi™) is doing to support this, in line with our recently adopted vision “evidence for sustainable food systems”.

Conversations about the future of food usually fit within one or more of the following areas:

  • Nutritious, affordable and sustainable diets for individuals
  • National use of environmental and other resources for food production
  • Sustainability of global food production and distribution of food to address the nutrient needs of everyone

Each scale has its own unique questions and challenges that need to be understood and addressed.

At the global level…

We will start with the large scale first. How does the world feed the world?

  • What food production is required to provide adequate nutrition for everyone?
  • How does this change as global population continues to increase?
  • What are the resource implications of this at a global level?
  • What are the impacts of large-scale changes in food production?
  • How big are the changes needed to be globally relevant?

In one sense the global scale question is easier to frame than the two smaller scales. There is only one Earth – there are no interplanetary trade flows to cover shortfalls or utilize surpluses – everything must balance within the planetary boundary. The total nutrition available is determined from the production of food commodities, and further processing and food formulation is largely a reorganization of the form in which these nutrients are presented to consumers.

The DELTA Model was developed to contribute to this global scale conversation by enabling a user to set the level of production for the major classes of food commodity and see the likely impact of this on nutrient supply for the global population. When we consider making changes to production on the global scale, we must also match this with an appropriate timeline of multiple years. The original version of DELTA provides significant insight on the role of the different primary production systems in providing nutrients to the global population (learn more here). A key conclusion from all our work to date with DELTA is that the global food system is, and must remain, “plant based and animal optimized.”

Further development of DELTA focuses on adding estimates of resource footprints for the selected production systems, starting with cropland use in DELTA 2.0 (learn more here). Consistent with the scenario “what if” concept of DELTA, the model does not enforce a hard constraint on production based on available land, but instead provides feedback to the user on the extent to which their proposed food system is feasible within the land area suitable for crop production.

Beyond 2.0 we will introduce additional resource footprints into DELTA, including greenhouse gases and the use of land for ruminant grazing. At the same time, we are looking at how we make better use of the more detailed food commodity and use data made available by the FAO towards the end of 2020.

An aspect that was part of the original concept of DELTA was to consider economic aspects of the food system. A key challenge that is neglected in the discussion of many high-tech alternatives is the level of capital investment required to establish these technologies at a scale that would make a material impact on global nutrient supply, and the implications of this for the cost of the resulting nutrition (learn more here and here).

At the individual level…

At the other end of the scale is individual dietary choice.

  • How can individuals within our society access the nutrients they need?
  • How is this impacted by the price of food items?
  • How do their choices impact on the environment?
  • How do choices potentially alter health outcomes?

These are questions that individuals may ask for themselves and are also relevant in the development of public policy. Potential outcomes include changes in dietary guidelines or changes in individual eating habits.

There is considerably more scope for an individual to change their diet than there is for change at the global scale. At the individual level a radical shift in diet may be made quickly and has no discernable impact on the food production system and supply chain. It is only when large collections of individuals make similar changes that this has an impact on the availability and affordability of food items, and the feasibility of these choices (learn more here). Whilst the global nutrition question is constrained by the boundaries of the planet, the individual nutrition question is limited by the range of foods available locally, and the wealth and choices of the individual.

Riddet Institute researchers used linear programming to determine the minimum cost for a nutritionally adequate diet based on a basket of food products in the USA (learn more here). Work in the Netherlands led to the development of Optimeal™, which starts from the Dutch reference diet and explores the impact of restricting the intake of certain foods on the carbon footprint and price through an optimization that seeks to remain close to the reference diet in terms of foods eaten thus addressing some of the cultural aspects of dietary change (learn more here).

Building from these ideas we aim to create an online tool to enable people to explore individual dietary choice, what levels of dietary change may be possible and practical, and the resulting impacts in any country for which the required food product information is available. The aim is to make it easy to customize this for use in any country for which the required food product information is available. Unlike DELTA, where the default time is currently 2018 for the base case and 2030 for the initial projections, the individual model (to be called IOTA) will work in an immediate sense (i.e., If I changed my diet today…).

At the national level…

In between these two extremes sits the national level question:

  • What is the best use of our natural resources?
  • How should we best utlise our land?
  • What should we grow or produce ourselves?
  • What do we export? What do we import?
  • How does this influence our environmental impact?

This is more complex than either the global or individual scales due to the movement of food items across borders. Food trade exists at some level for almost every country in the world: there is not the same hard boundary that exists on the global scale (i.e. only one planet) that requires domestic self-sufficiency for any given nation. Nutrient gaps can be addressed through imports and surpluses addressed through exports – although this only partially occurs today. Food trade occurs when one nation has to offer what another wants, so the options are constrained, although wealthier countries are better able to purchase what they want. As the DELTA Model shows at a global level, we already produce enough food energy and protein to meet the needs of the expected 2030 population, however not everyone has equal access.

Our current work at the national level is to understand the present state of food production and trade flows expressed as bioavailable nutrients rather than mass of food items. This provides a human nutrition centric perspective. The following charts from DELTA show, from a food energy perspective, the production, trade flows and consumption for New Zealand, Australasia, and Oceania.

The “Produced” column shows the per capita per day production of energy in the country or region. Oceania is dominated by the food exporting nations of New Zealand and Australia and there is a considerable surplus of food energy at both the regional and sub-regional scales. However, when we just look at New Zealand, we see a significant import of plant-based food energy. Similar charts are available for all 29 of the nutrients considered in DELTA, in all countries. Taking this a stage further, with our collaborators at University of São Paulo we are looking at flows of bioavailable nutrients between exporting and importing countries to show the evolution of the trade network.

Whilst the above helps to understand the current state of nutrient flows, it does not address the questions about most effective use of a country’s resources (environmental, social, economic). To do this, we are developing a proposal for multi-year research to investigate the national and sub-national questions, using New Zealand as a test-case. This will lead to the development of an integrated model framework that connects primary production and food trade decisions with their associated resource and economic implications, through to consumer nutrition and associated health and wellness outcomes. The objective is to develop a model that works for New Zealand and can, through changing the data inputs, be applied to other countries.

As with DELTA, the approach will be scenario-based, with users specifying a potential system and the model estimating the implications of this system in terms of the various capitals. By doing this we hope to contribute additional evidence-based insights to national and local conversations about food systems.

All three scales are important and complementary

The food system must function at all scales from the global, through the national, to the individual level. Each has unique characteristics and challenges that impact on our ability to make changes. Aspects that are easy at one level, create complications at another.

Importantly, no one perspective will deliver a full understanding of the food system and the way forward to greater sustainability.

  • An individual’s diet that is healthy, affordable and has a low environmental impact will not necessarily be applicable more widely.
  • National level food preferences and cultures, as well as what can be produced in a country, will mean that variation must exist between healthy and sustainable diets and food production in different parts of the world.
  • Similarly, it is not sufficient to understand what sustainable dynamics are for a single country, as countries do not operate in isolation: international food trade and global production must also function sustainability.

SNi is developing tools to help people explore food system challenges and provide evidence for sustainable food systems at all three scales.

Glossary

FAO report on “harmful” agricultural subsidies calls for urgent change

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A report co-produced by the FAO, UNDP and UNEP has analysed current levels of agricultural support (such as subsidies, tariffs, and incentives) in 88 countries. Their finding was that the majority of the total support value could be considered harmful, largely through distorting food prices, indirectly promoting unhealthy diets, or damage to the environment.

Around US$540 billion, or 15% of the total value of agricultural production, is paid out in agricultural support each year. These funds are split almost equally between farmer subsidies (reducing the cost of agricultural inputs or rewarding production of specific commodities) and price incentives (tariffs or subsidies on trade). A small proportion goes towards non-specific, general sector services, such as agricultural training, infrastructure development and product safety.

The authors state that over two thirds of agricultural support has the effect of distorting food prices and increasing the environmental damage of food production. This is often embodied in support for production of foods with low nutritional value (e.g., sugar cane) or high carbon emissions (e.g., ruminant meat).

Most agricultural producer support is currently focused on specific commodities. The foods receiving the greatest support were sugar, animal products and cereals, with cotton a highly supported non-food commodity. Developing countries tend to predominantly subsidise production of staple crops, whereas animal-sourced foods generally receive greater support in developed countries.

The report pushes not for the elimination of agricultural support, but rather its repurposing. This topic was also discussed at the UN Food System Summit in September 2021. Many parts of the food system have evolved some degree of dependency on the current support structures, so any changes must be carefully made to avoid unintended consequences. Consumers need access to affordable healthy diets, but producers also need to be assured of an income. The authors’ general conclusion was that agricultural support should enable environmental, health, and social progress, as well as economic gain.

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Glossary

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Need or Greed?

Adjunct Professor of Massey University and the Riddet Institute and Fonterra Chief Science and Technology Officer, Jeremy Hill, last week contributed to COP26 on the future of sustainable food systems. SNi research featured heavily in this contribution. Prof Hill outlines some important aspects of today’s food system that are poorly understood, and examines the role of meat, dairy and future protein sources in achieving sustainable nutrition.

The global food system

SNi work on global food biomass production and nutrient availability has shown that the current global food system is already plant-based, but with animal-sources of nutrition playing a vital role in overall nutrient provision. Of the 10.6 billion tonnes of food biomass that left the world’s farms and oceans in 2018, 9.2 billion tonnes (87%) was plant material and 1.4 billion tonnes (13%) was animal-sourced. On a global basis we have mapped the flow of this food biomass, shown in the below figure.

Biomass flows through the global food system.

On a simple biomass basis, 1.4 billion tonnes (15%) of human-edible plant biomass leaving the world’s farms was used as feed for animals, to supplement non-human-edible feed such as grass. This was used to produce the 1.5 billion tonnes of animal-sourced food leaving the world’s farms.

At face value, this does not look very efficient, considering the environmental impact of animal production systems. However, this hides the different nutrient contributions that come from plant and animal sources of nutrition, land use suitability for cropping and major differences in the supply chain losses, waste, and non-food uses of the plant and animal contributions to the global food system.

The fact that only 1.4 billion tonnes of human-edible plant food biomass was used to feed animals also highlights that a significant proportion of animal nutrition does not come from human-edible plant material but from straws, silages, pastures, food waste, and so on. The scientific publication: Livestock: on our plates or eating at our table? provides an excellent overview of the feed versus food debate and found that, although livestock consume one third of global grain production, 86% of the biomass consumed by farmed animals is inedible for humans.

75% percent of what is eaten by the global population comes from plants; but also, 91% of post-farm food losses and waste comes from plants.

Of the food material entering the food chain, 86% of animal-sourced food material produced is consumed but only 47% of the plant-sourced food material.

Looking at global food supply, flows, consumption, and losses gives a different perspective on efficiencies. The food system is already plant-based and from the perspective of production, consumption, and waste, animal sources of food have very efficient aspects. But that is the case for food biomass; what about nutrition?

Nutrition supply and demand

We often hear about the “need” to produce more protein to meet the growth in demand for protein-rich foods. This includes the “need” for more meat and that using current systems to produce this amount of meat is not sustainable. We have recently shown using the DELTA Model for global nutrient provision that the world not only produces enough protein to cater to the nutritional requirements of our current global population (see below figure), but that current production could meet the protein and indispensable amino acid requirements of a population projected to reach almost 10 billion by 2050. The issue is not production but distribution, access, and affordability of protein.

A value of 1 indicates that global nutrient availability exactly meets requirement, less than 1 a shortage, and greater than 1 a surplus. The coloured bars show the global average nutrient availability. Red bars indicate nutrients with insufficient availability, orange bars are just meeting requirement, and green bars clearly exceed the target. The error bars show the range in nutrient availability between the 10 th and 90 th population percentiles based on country level averages. 

In contrast to the global availability of protein, there are currently large gaps between global need and global supply of certain micronutrients that will only get bigger unless the food system changes to address these gaps. Critically, animal-sourced foods and oil crops are currently the major sources of key micronutrients in deficit, such as calcium and vitamin E, with animal-sourced foods also important sources of globally limited nutrients such as iron, zinc, potassium, vitamins A, B2, and B12.

For most nutrients there is a wide variation in their availability between countries, and clearly for some countries, access to sufficient nutrition drops below target intake (see above figure). These gaps have the potential to increase with an increasing global population and especially if, as is currently the case, the population increase is in countries where access to nutrition is already below target requirements.

‘Meating’ needs?

Thinking about the current growth in meat production: how much of this is meeting needs rather than catering to the greedy? Here I use the term “greed” in the context of eating a particular food beyond the point of its contribution to a balanced diet and nutrient requirements, with no implication of moral judgement. Nevertheless, it is hard to argue that this behaviour is in keeping with sustainability, as over-consumption can be considered a form of food and nutrient waste.

According to the FAO, global meat production grew 44% over the period 2000-2019. But how much of this growth is servicing need rather than greed? How many of the existing or new consumers are eating meat above the recommended target intake? Quite a considerable number according to The Global Burden of Disease Study (see below figure). Yet, as with overall protein availability, the consumption of meat is geographically uneven.

The dotted line represents global average consumption levels and shaded green area the uncertainty in the level of optimal intake. Reproduced from Afshin et al. 2019 under the CC BY 4.0 license.

Milking the planet?

At 844 million tonnes, milk represents 60% of the animal-sourced global food biomass. So how does its consumption compare with meat? Clearly the picture for milk is very different, as is calcium intake (see below figure), with the per capita consumption of milk falling short of optimal intake in all regions of the world.

The dotted line represents global average consumption levels and shaded green area the uncertainty in the level of optimal intake. Reproduced from Afshin et al. 2019 under the CC BY 4.0 license.

Our work at SNi has found that although milk represents 60% of animal-food biomass, milk is less than 8% of the total food biomass leaving the farm gate, and contributes 49% of the calcium, 24% of vitamin B2, 22% of vitamin B12, 15% of vitamin A, 12% of the protein, up to 18% of the indispensable amino acids, and makes a significant contribution to a range of other nutrients consumed by the global population. Moreover, at only 7% of global dietary energy, milk is not only nutrient rich (content and range of nutrients) but also nutrient dense (content and range of nutrients compared to number of calories).

Clearly milk plays an important role in global nutrition and from a consumption versus recommended intake perspective, it would appear we should be producing more milk not less. But that’s nutrition and health, what about environment?

Although the food system in its entirety is estimated to contribute 20-30% of total GHG on a carbon equivalent basis, dairy’s contribution is 2-3%. Considering milk’s global nutrient contribution, its nutrient richness and nutrient density, dairy looks like a pretty good deal. A good deal, but not a perfect deal and, for the very reason that it is so important to global nutrition, we should focus on making large improvements to the efficiency of milk production and its environmental footprint, especially if we need to produce more rather than less milk in the future.

Alternative Reality?

Of course, another often publicised approach would be to attempt to replace milk and other animal-sourced foods with alternative sources of nutrition that have lower environmental footprints.

As discussed earlier in the article, the issue with global nutrition is largely about affordability and access, i.e. what the global population needs. As such ‘plant-based’ alternatives and new technologies, such as precision fermentation or mammalian cellular production, should aim to produce substitutes in more affordable and accessible formats that provide the same nutritional benefits as existing plant and/or animal sources of those nutrients.

We would also argue that improvements to the productivity and sustainability of existing plant-sourced or animal-sourced foods should look to do the same.

Whether consumers of such alternative and novel foods are actually doing good rather than just feeling good about what they are doing will depend on several factors.

  • What does this consumption mean for global food biomass production, losses, and waste?
  • Are the alternatives as nutritious as the foods they are substituting?
  • Do the alternatives have lower environmental footprints for water, land use etc. as well as just greenhouse gases per unit of nutrition?
  • Are the alternatives consumed responsibly to the point of need and not well above what is required, as a result of “greed”?
  • Are the alternatives cheaper to produce and distribute and can they be sold in such a way that it increases global access to nutrition?
  • Will companies producing alternative proteins transform the global food system by democratising it and providing more access to affordable nutrition? Or will they concentrate control and remain beyond the reach of many global consumers?

SNi was established to help create a better understanding of the global food system and particularly the critical issue of how it can provide all the nutrients required by everyone on the planet. Its purpose is to help people explore what changes to the system may be possible, but also what will be practical.

If we are to have a sustainable world and, by implication, a sustainable food system, then there is certainly the need for radical change. However, we do not subscribe to the view that all aspects of the food system need to be disrupted. Radical improvements in the existing food production system will be equally, if not more important, than radical changes to the food production system.

But to be clear there will be no room for laggards, and we do see an important role for new ways of producing the nutrients we require, such as precision fermentation, but that these will be complementary to rather than totally disruptive to existing food chains. In doing so everyone has the right to choose the diets they want to follow and certainly for those that can afford to do so, have broad options for what they can choose.

When it comes to the food system, perhaps the most important changes of all are the changes we make ourselves. Here I would start with consuming closer to what we need and cutting back on the greed.

Glossary

Photo by Spencer Davis on Unsplash

Combined nutrition and environmental scoring

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A recent study of Belgian consumers has indicated that product labelling has the potential to improve the nutritional quality of food choices, but was less successful for improving the environmental impacts.

The Nutri-Score label, a traffic light-style graphic capturing nutritional quality to be displayed on food packaging, is widely used on products in Europe. However, there is increasing debate on the role of consumer choice in the environmental impacts of food, as well as their nutritional and health qualities.

Increasing information is available on the environmental impacts of individual food items via life cycle analysis. With this have come many offerings for product environmental labels, produced by a several authorities. This study analysed the potential of an Eco-Score – very similar to the Nutri-Score in its presentation – to improve the environmental impacts of consumer food choice.

805 consumers were trialled in an online supermarket environment stocked with 11 food products. They were asked to buy what they thought they would need to feed six people spaghetti bolognaise.

Participants were allocated to various study groups. Some were shown just the Nutri-Score and Eco-Score, while others were given more information, such as the CO2 per 100g, or statements encouraging reduced meat intake.

The nutritional quality of foods selected improved when the Nutri- and Eco-Score were shown (largely due to reductions in pork consumption). However, the environmental impact of choices did not improve. Specific recommendations, such as those encouraging reduced meat intake, were able to improve both aspects (largely due to reduced beef consumption).

While this was a limited study, using an online environment with minimal offerings, it presents some interesting questions. What would the results be in a physical environment, where choices are made more quickly? Are two separate scores too much information for a consumer to quickly weigh up when making a purchase decision? Were the results confounded by the success of the Nutri-Score, that may already be ingrained in consumer decision making? Do consumers weight nutrition above the environment in their food choices?

This study further highlights the challenges of product environmental labelling. Many such labels exist, and they appear likely to become commonplace in the future, but how can we ensure that they make a positive difference to decision making? And how should the calculation of both Nutri- and Eco-Score capture all the relevant information when food has such diverse impacts?

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Glossary