Environmental pawprints

Consumers are increasingly aware of the environmental impacts of their diets and lifestyles, with everything from transport to dinner coming under scrutiny for its footprint. Pets are also coming under the microscope, principally for the role of their diets in the wider food system.

Most research to date has focused on cats and dogs, due to their high domesticated populations globally and industrial food production systems. Both also consume food with a relatively high content of animal-sourced ingredients: around a third of the energy in cat and dog food is animal-sourced, compared to a fifth for people. In the US, cats and dogs consume around 20% as much food energy as the human population.

Quantifying the environmental impact of cat and dog food is challenging since the majority of ingredients are by-products of human food production, e.g., bone meal or grain leftovers. In the DELTA Model®, some of these ingredients are classified under “Other uses”, while some fit in the “Inedible portion” class, showing some of the challenges around assessing these commodities. Some studies allocate all impacts of production to the primary product, making the by-product footprint-free, while others allocate impact based on the mass or economic value of the ingredients.

A recent study used the economic approach to calculate that 1-3% of global agricultural emissions are on account of pet food production, with lower percentages for land and water use. Another calculated the impact of the US pet population’s diet as around 25-30% of the human population’s, including land, water, and fossil fuel use.

One estimate stated that around 140 million people could be nourished using the energy currently entering the US pet food system. However, this was purely an energy calculation, and did not include full human nutritional requirements. Moreover, it does not account for the fact that the food sources demanded by people do not match the lower quality ingredients used in pet food. However, there are increasing purchasing trends towards premium products that do include substantial proportions of human edible food.

As the impact of pet food is not negligible, there have been calls to reduce this pawprint. This impact is affected by many of the same issues as the impact of the human diet: food waste, overconsumption (and consequent non-communicable disease), and the differing impacts of different food sources. Thus, similar solutions can be tried, such as minimising waste, correct portion sizing, and inclusion of environmental impact alongside nutrition in ingredient selection.

Pet ownership is on the rise globally. While the benefits of pets are clear to any pet owner, and have measurable benefits for human wellbeing, they cannot be left out of any holistic approach to measuring or reducing environmental impact.


Adding value with bugs 

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While the idea of eating insects may repulse some people, eating animal products from livestock reared on insects may be less off-putting. Black soldier fly larvae are an insect often produced as feed for livestock, and a recent research article has examined their potential in converting food waste to feed at scale.

Food waste represents lost inputs and value as well as having negative impacts of its own. While reducing food waste is an ongoing challenge, the production of some waste is inevitable. While we commonly think of food waste at the consumer or retail level, losses also occur higher up the supply chain with the producer. For many crops, such as soy and maize, only a few percent of the total production mass entering the human food supply chain are wasted, but this still amounts to millions of tonnes of plant matter globally each year. Conversion of this waste to animal feed is one way to include food waste in a circular economy, and to approach a zero waste system.

Some of the advantages of farming insects on food waste include the ability to co-locate production centres of any size locally to either food waste production or to the farms that will use the feed, due to the flexible growing conditions of these insects. Insect production near crop production has the added advantage that compost – the by-product of insect farming – can be returned to the field as fertiliser.

The yield of larvae for feed from food waste is up to 12%, over a period of as little as two weeks. The larvae are also a high-quality feed, with protein contents of 32-58%. In the case of many commercial aquaculture fish species, they can be a complete feed replacement.

The authors conducted an exploratory life cycle analysis of a hypothetical UK scenario where a large portion of food waste was diverted to insect production. They found that this resulted in a reduced environmental impact compared to biogas production from food waste for indicators such as global warming and land use, but greater impacts for indicators such as water consumption. The environmental impact of larvae production could be further slashed if electricity consumption were reduced or sourced renewably.

Commercial operations are already exploiting the larvae opportunity. In the UK, deals have been struck between supermarkets and insect farms to produce chicken feed from retail food waste. Elsewhere, “the world’s largest insect farm” has been proposed in the US, co-located with a large pet food factory.

Valorising unavoidable food waste and keeping the benefits within the food system has strong potential. Building such possibilities into food system models such as the DELTA Model® will allow their global potential to be better understood.

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PLANET food system explorer launched


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GOAL Sciences have recently launched their new online tool for viewing the movement of food through the current global food system. The visual, interactive nature of the tool is accessible to anyone with an interest in where food comes from, and where it ends up.


The PLANET tool uses data from the Food and Agriculture Organisation on global food production, trade, processing, and end use. The user can examine the flow of food at a global or national level, for either total food mass or total food protein.


For example, a user might be interested in cereal production. They can use the tool to see how much of each cereal crop is produced around the world (nearly 3 billion tonnes), that around half goes to processing into food, a third into animal feed, and the remainder into uses like next year’s seed, biofuel production, or is wasted along the supply chain.


The PLANET tool is complementary to the DELTA Model®: both use the same data as a foundation, so the two can be used in tandem. PLANET allows the user to visually understand how food flows in today’s world, while DELTA shows you the nutritional value of that food to the world, and lets you explore changes to the system in the future.

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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.

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The many facets of food waste

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In a scoping review of the literature around food losses and waste, authors in the International Journal of Environmental Research and Public Health identified the links between unconsumed food and nutrition, health and environmental impacts.

Food losses refer to food that does not reach the retail stage, due to losses on farm and along the supply chain. Food waste encompasses retail and consumer waste. This review discussed both losses and waste, as well as including discussion of plastic waste from food packaging.

The authors made the connection between food waste and nutrient waste, finding that both the magnitude of waste and the specific nutrients wasted varied greatly between individuals and between studies. An interesting link was made between waste and diet quality: higher quality diets were associated with greater food waste in some studies, particularly waste of fruit and vegetables. Fruit and vegetables have some of the highest loss and waste proportions of all food groups (15-60%), due to the perishability of these foods and their perceived value by consumers. The authors were able to tie this fruit and vegetable waste back to environmental impacts such as wasted irrigation water, cropland and pesticide use.

Plastic packaging in the food system is a double-edged sword. Plastic is very effective at extending the shelf life of food, and protecting it from contamination and damage. However, current high plastic production and waste is recognised as a sustainability challenge. In Europe, 30% of plastic waste is recycled, 31% is sent to landfill and the remaining 39% is incinerated.

As well as the environmental impacts of plastic packaging, the review covered the commonly discussed links between food waste and environmental impacts. This includes both the waste of inputs (e.g. the land use, fertiliser use, and other inputs associated with production of food that is not consumed) and the impacts of disposal of food waste.

Looking to food waste solutions, most interventional trials in schools (such as those that reduced portion sizes) were successful in reducing food waste in this environment. Looking at food banks and food redistribution, numerous nutritional deficiencies and excesses were identified in existing redistribution efforts. It was found that effective redistribution planning increased nutritional quality and reduced waste.

While the authors discussed the need to reduce overconsumption of food from a health and packaging waste perspective, they did not discuss overconsumption itself as a form of food waste. Food and nutrient intakes above safe recommended levels pose both a health risk and are analogous to food waste: this food is not serving a positive nutritional purpose. Therefore, the inputs necessary in the production of this food could be considered wasted, and the food cannot go to the benefit of those who may need it.

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The role of processed foods in a sustainable food system

There exist negative consumer perceptions on processed and ultra-processed foods, however such foods are commonly misunderstood. Here, we explore some of the reasons behind this, the varied definitions and types of processed foods, and how they are essential to the sustainability of the global food system.

Food processing is defined as making changes to a food to alter its earing quality or shelf life. Processed foods are often criticised and have a negative perception among consumers. A survey carried out by International Food Information Council found that 43% of consumers were not in favour of the consumption of processed foods.

The 2020 edition of the Global Nutrition Report claims that current food systems do not enable people to make healthy food choices, and one of the reasons for this is that highly processed foods are available, cheap and intensively marketed. They state that processed foods “high in added sugars, trans fats and salt, as well as low in fibre and nutrient-density” are now comprising a significant share of many diets globally, however they are not aligned with the World Health Organization’s definition of a healthy diet.

This is true for some ultra-processed, energy-dense and nutrient-poor foods. It is critical to minimise foods high in energy but low in essential nutrients and instead prioritise nutrient-rich foods. Many processed foods fit this description of nutrient-rich and can play an important role in a sustainable food system. Some foods classified as ‘ultra-processed’ by the Global Nutrition Report are processed for good reasons, with minimal impact on their nutrient content. Unfortunately, research shows that consumers have a limited understanding of what food processing is, and the important benefits it can provide.

Processed vs ultra-processed

The term “ultra-processed food” is problematic. A review of the use of this term found diverse inconsistencies in its use by policy and research, but almost exclusively with negative connotations and instructions to minimise their consumption. However, at least half of the US energy intake is from “ultra-processed foods”, by some definition, thus their avoidance or removal would be challenging.

The main aim of classifying foods under the category of ultra-processed and attempting to minimise their consumption is to reduce population intakes of free or added sugar, salt and other ingredients added to food during specific processes. This is an admirable goal, but requires consumer understanding of the differences between individual processed foods. Wholegrain bread, milk and frozen vegetables are all processed foods, but should be thought of differently by the consumer than a frozen pizza, high in energy and low in nutrient density.

Processed foods play a key role in nutrition and safety of food

The global population is growing, expected to reach almost 10 billion people by 2050. However, the planet is limited in its resources, creating a significant challenge to feed this growing population. Therefore, it is essential to optimise the efficiency of producing and distributing food, in order to ensure there is sufficient nutrient availability to meet global requirements. The DELTA Model tells us that based on current food production, there are already gaps against requirements for many essential nutrients – such as calcium and vitamin E – and these gaps could grow in size and number as the population does.

Processing can improve the nutritional quality of food. Processing can improve the bioavailability of essential nutrients – meaning more of the nutrient can be utilised by the human body. An example of this is processing legumes (via heat treatment, fermentation, germination or simply soaking) to increase the bioavailability of iron and zinc. Foods can also be fortified through addition of critical nutrients that may be limiting in some diets, as commonly performed for breakfast cereals. Processing therefore plays a key role in increasing nutrient availability to the growing global population.

In addition, many foods have a short shelf life. A variety of fruits and vegetables, as well as most animal-sourced foods, cannot be stored for long periods of time in their raw form. This can create potential food safety issues, or nutritional quality can decrease over time. Moreover, some regions do not produce sufficient food to meet the requirements or demands of their local population, meaning that it must be imported, taking time to reach those that need it. In addition, some food products are seasonal, where supply will exceed demand for some months of the year, and vice versa for the rest of the year.

It is therefore essential to extend the useful life of nutrient-rich foods to avoid safety issues and preserve nutritional quality. This can be achieved through processing. For example, raw milk has a relatively short shelf life, but this can be extended by processing it into milk powder, cheese or yoghurt. Milk is a nutrient-rich food, and processing allows as much of this nutrition to reach consumers as safely as possible. Likewise, freezing or canning of fruit and vegetables can keep these foods stable for as long as they remain in this state. Pressing oilcrops to produce vegetable oils allows the nutrients in these crops to be utilised in a wider variety of ways than the raw form allows. While some of these techniques are modern, such as freezing and canning, others, such as fermentation and pressing, have been instrumental in the human diet for millennia.

Processed foods help to increase equity of food distribution and reduce waste

There is a global issue of inequitable food distribution and food waste. The world produces enough food energy to feed nearly 9 billion people. The reason 1 in 9 people are hungry is due to inequitable distribution of food, caused by geographical and socio-economic factors.

Secondly, as explained above, processing can extend the useful life of foods. This can help to minimise food waste, as less will be thrown away due to perishability. A study performed in Austria found food waste can be reduced by six-fold when frozen foods are compared with fresh foods, while another found that frozen foods are wasted half as much as fresh foods. This in turn reduces the environmental impacts of food waste, and increases the availability of food. While frozen food supply chains are not available in all parts of the world, drying and canning can have similar outcomes.

While eliminating food waste is not the complete solution for a sustainable food system, it can play an important role in increasing the availability of nutrition to meet global requirements. Extending the shelf life of food also means it can be transported to regions that do not provide sufficient nutrients to sustain their local population. In addition, processing can improve the ease of this transportation. This plays a vital role in addressing the issue of equitable distribution of food.

Processing encourages consumption

Economic, cultural, and social factors will play an essential role in achieving a sustainable food system. Consumers must want to eat the food available to them, and be able to afford it. Food processing can help increase the convenience and variety of the foods available. Food processing can be used to improve the taste, texture and functionality of foods, encouraging consumption. This is particularly important for nutrient-dense foods containing critical nutrients that can often be limiting in diets. Processing can also help to reduce the cost of storing or transporting food, and seasonal price volatility, making nutrition more affordable.

Food processing plays a key role in the provision of adequate nutrition to feed a global population. Production and consumption of high-energy and nutrient-poor foods should be kept to a minimum, and consumers need to be able to recognise these foods without labels like “processed” or “ultra-processed”. Processing can help to improve the safety and nutritional quality of foods, reduce waste and improve distribution, and encourage consumption of nutrient-rich foods. Use of processing techniques for the right purposes should be encouraged.

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Circularity in the food system

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Research at Wageningen University & Research has been exploring the role animals could play in a circular food system, by converting ‘leftovers’ into valuable food.

Associate Professor Hannah van Zanten, who spoke at the SNi Feed Our Future event in June, leads a team of researchers modelling circular food systems and studying the role that animal production would play. The idea is that farm animals can play a crucial role in sustainable food systems by not consuming human-edible materials, but rather converting forage and ‘leftovers’ (such as crop residues, co-products and unavoidable food waste), into valuable food. In this way, nutrients would be recycled into the food system that would otherwise have been lost.

They report that circularity would also minimize competition for land between feed and food, while still allowing the provision of fertiliser from animal manure. Compared to our current system, it would free up around a quarter of global arable land that is currently used to grow animal feed. This approach would however change the availability of animal-source food for human consumption.

Their modelling work estimated that one third of global protein requirements could be supplied by animals using a circular approach – comparable to current protein provision in the DELTA Model. However, it would require for differing priorities in selecting producing animals due to the reduction in cereals available for feed.

Circularity would also take different forms in different parts of the world. For example, low population densities, high pasture coverage and extensive production systems in NZ mean less food waste and by-products would be available and distributing these to livestock would be challenging. However, in Europe, high population densities coupled with more intensive production would better facilitate implementation of several of the circularity principles.

Moving towards a circular food system requires a food system perspective. It is important to consider the entire food system and the interconnectedness of different food production systems, rather than thinking of different components in isolation.

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Building on the robustness of GHG emission estimations of the food system

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A recent article in Environmental Research Letters has provided new estimates for greenhouse gas (GHG) emissions from the food system. This study considered emission contributions from a range of food-related activities at the country level over the period of 1990-2018. Inclusion of components such as land use change, food waste and food transport at the country level saw both consistency with existing estimates and suggestions of underestimation by other studies.

The GHG data used included crop and livestock production, on-farm energy use, land use and land use change, domestic food transport and food waste disposal. Inclusion of all these components built the robustness into GHG emission estimates for the food system. The key findings reported were:

  • In 2018, a third of the global anthropogenic emissions could be attributed to the food system. Of these, three quarters came from behind the farm gate and in pre- and post-production activities. The remaining quarter was from land use change of natural ecosystems to agricultural land. This finding is consistent with published scientific literature, strengthening the results.
  • Per capita emissions were also measured and showed a decrease over the time period 1990 – 2018. Developed countries were found to have twice the per capita emissions of developing countries.
  • Conventional IPCC methods of calculation, used to report on national GHG inventories, underestimated the emission contribution of the food system. Several food-related emission sources were missed in the conventional calculation, such as on-farm energy use, domestic food transport and food waste disposal.
  • Land use change decreased over time, while the authors suggested emissions from energy use beyond the farm gate increased their contribution to total food system emissions.

Studies such as these provide a different perspective on emissions allocation, with some benefits, including better quantification of food system emissions. They also provide insight into opportunities for emission reduction strategies across the food system and at the country level. With improved measurement supporting improved management practices, these perspectives are an important stepping stone to GHG emission reduction.

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Waste and losses in the global food system

This Thought for Food article examines the loss of nutrients as a result of food waste. Not all foods are wasted to the same extent, and thus neither are all nutrients. Aggregate numbers for global waste or waste reduction targets mask these important variations.

When considering the impact of changes in the food system, we need to consider the supply of nutrients, as well as the supply of foods. The primary role of the food system is to provide nutrients – in the form of foods – to meet the needs of the global population.

Distinction should be made between food losses and food waste. Losses are the decrease in edible mass along the supply chain prior to retail, and waste the decrease that occurs at the retail and consumer end of the chain. Read More

When demonstrating the impact of food loss and food waste, we should consider the decreases in available nutrients.

When we lose or waste foods containing nutrients that are in abundant supply, this is less critical from a human wellbeing point of view than the loss or waste of foods rich in undersupplied nutrients.

Ways of improving the future food system could include:

  • reducing loss and waste (and potentially lowering production) where we have excess nutrient supply
  • reducing loss and waste (and potentially increasing production) where there are nutrient shortages

So where are the nutrient shortages?

From a macronutrient perspective, current estimates are that nearly 690 million people have insufficient protein and/or energy intakes. However, micro-nutrient deficiencies (hidden hunger) are also an enormous problem: globally, anaemia (iron deficiency) is estimated to impact 43% of 0-5 year olds and 38% of pregnant women; up to 1.8 billion people may have insufficient iodine intake; and 17% of the global population is at risk of zinc deficiency.

The DELTA Model has been created to help people explore future food production scenarios. It uses data on food production, losses, wastes and end uses, coupled with food composition, nutrient bioavailability, population forecasts and nutrient requirements to determine whether a future food system scenario can meet the nutrient needs of the global population. Modelling the food system shows that globally, with equal distribution, we have enough macro-nutrients for all, even carrying current production levels through to feed the 2030 population.

For protein – often cited as a nutrient we need to produce more of to satisfy a growing global demand – there is already enough protein available globally to provide the target intake for the expected 2050 population based on current nutritional guidelines, if it were equitably distributed.

This may seem surprising, but a challenge in discussing the future of food is in separating the nutrition we need, and the nutrition we might want or prefer. Protein is a good example of this. Statements that we “need to expand production by 70%” by 2050 are based on consumer demand rather than requirement. The DELTA Model exposes the differences between demand for specific nutrients such as protein and population requirements.

However, the global story differs for the micronutrients. We are already limited on total supply of Calcium and Vitamin E and will also be limited on Iron, Potassium, Vitamin A and Zinc by 2030 unless changes to the food system are made. That is, even if distributed equally, there is not enough of these nutrients to meet everyone’s needs.

When we look at the distribution of nutrient supply at a country level the picture is worse. The variation in nutrient supply in 2015 shows that a significant proportion of the global population had insufficient access to Calcium, Vitamin E, Iron, Potassium, Zinc, Vitamin A, Riboflavin, Vitamin B12, Fibre, Folate, and Vitamin C.

Relative nutrient supply distribution at a country level in 2015.  All values are normalised to the target intake with the coloured bar showing the global average supply and the error bars showing the range in country level supply from the 10th to the 90th percentile of the global population.

Waste varies with food type, which affects the supply of nutrients in different ways.

Let’s consider a simplified food supply chain: On Farm -> Supply Chain -> Retail -> Consumer

  • On Farm losses are challenging to quantify, as these may include crops or parts of crops not harvested or not used for human food. These quantities are often not recorded either. In many farming systems, waste materials on farm are used to provide food for animals with almost 30% of the global livestock ration coming from crop residues, by-products and coproducts.
  • Once food commodities leave the farm, losses occur along the supply chains that connect farms with retail, including as part of processing into other products. With more expensive commodities there are strong economic drivers to reduce losses through supply chain infrastructure. For less valuable commodities this may not be the case. Well-developed supply chains seek to recover valuable nutrients from by-products and “wastes” by processing into additional foods, animal feeds, or for other uses.
  • At the consumer end of the supply chain, food may be discarded at retail or in-home for its appearance, age, or various other reasons. Consumer waste is generally greater in high income nations where there is the luxury of choice. Individual consumers or households often lack the resources and the incentives to repurpose food waste and inedible material.
Per-capita food waste by country income bracket expressed as Wasted Daily Diets – the number of additional person days of nutrition wasted based on the first limiting nutrient. Data from Chen et al. 2020. 

Across the supply chain economic drivers mean we waste less of what is expensive, which – combined with the perishability of many fruits and vegetables – means food loss and waste is dominated by plant material. Over 20% of fruits, nuts, and vegetables, and their associated nutrients are lost or wasted after leaving the farm gate. Losses of animal products are 7-10%, and losses of more stable plant commodities (e.g. pulses and sugar) are up to 8%. This means that there is less potential to increase the supply of nutrients that are mainly found in animal sourced foods by reducing loss and waste, compared with nutrients common in plant foods. For example, an 50% reduction in all food loss and waste would result in a 16% increase in Vitamin C supply, but only a 6% increase in Vitamin B12.

Overconsumption is a form of waste

The other aspect of waste that needs to be considered is overconsumption. Nutrients consumed in excess of requirements are either excreted in bodily wastes, or in some cases – as with excess food energy intake – accumulated within the body. Once a certain level of supply has been achieved, further intake gives no further benefit to the individual and is thus a form of nutrient or food waste. When we look to the future, reducing overconsumption waste may have a significant impact on global nutrition.

Taking the previous example of Vitamin C, the range in 2015 nutrient supply at a country level was from around 66% of the daily requirement, to more than 2.8 times the target. For Vitamin B12 – sourced almost exclusively from animal foods – the 2015 availability varied from 40% to 1.75 times the target. Reduced waste and more equitable distribution of foods would increase the availability of nutrients to the populations currently below the target.

When considering the question of what to do about food waste, we should also think about the nutrient waste that occurs as part of this. Waste of nutrient rich foods has a greater impact on our ability to nourish populations that waste of nutrient poor foods. Waste occurs at all stages of the supply chain, and there are many forms of consumer waste – including excess intake. Quantifying and addressing how and where we waste important nutrients is a promising route to reducing nutrient deficiencies.

This Thought for Food was written by the SNi team in collaboration with Prof Thom Huppertz and Prof Wayne Martindale.

Glossary

Photo by Joshua Hoehne on Unsplash

Feed Our Future event to bring science, government and industry together

The Riddet Institute is this week hosting an event to bring together food system stakeholders and decision makers for accessible evidence-based discussion of the key global issues and the local decisions that we need to make.

Sustainably feeding a growing population is a global problem, but also one for New Zealand to consider. Where does our reputation for high quality, premium food products fit in a hungrier world? How can kiwi innovation and ingenuity make a difference to the global future of food?

The event will explore the current conversation of sustainable food, bringing moderation and balance to what is often a debate of extremes. National and international experts in the fields of nutrition, food waste, food systems, life cycle analysis and consumer science will speak on these important issues, with open discussion from the attendees.

This dialogue will inspire our future decisions and put New Zealand at the front of the sustainable food systems debate.