DELTA Model published in Journal of Nutrition

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Results of the SNi DELTA Model have this week been published in the Journal of Nutrition. The paper details the construction of the model, the scope of its use, and some key results that challenge widely repeated ideas in the food system.

As detailed in the paper, the DELTA Model is an online tool that allows users to design global food system scenarios (in terms of production, waste and use) and see the outcomes for human nutrition. For example, a user can design a scenario with increased food production and decreased food waste, which the model will then use to calculate the nutrients available to the global population. This value is then compared to the nutrients that the population requires, calculated using demographic data coupled with age and gender specific nutrient requirements.

How does the model work?

DELTA was developed using publicly available datasets from international organisations, complemented with key information from the scientific literature. It takes global food production totals and runs them through a calculation pipeline:

  1. Allocation: food items are allocated to their uses. This includes use as animal feed, processing into other food or non-food commodities, seed for following growing seasons, and non-food use (such as sugar crops for biofuel production). The amount wasted along the supply chain is also deducted.
  2. Consumer use: a substantial amount of food matter is not consumed, either because it is considered non-edible (such as animal bones and vegetable peel), or it is simply thrown away uneaten.
  3. Conversion to nutrients: food composition data are used to convert the total amount of food consumed into a total amount of nutrients consumed. 29 essential nutrients are included.
  4. Bioavailability scaling: specific nutrients are scaled for bioavailability, i.e. the ability of the body to utilise these nutrients when consumed in certain foods.

The total amount of bioavailable nutrients is then compared to the requirements of the global population. This can either be today’s population, or a forecast population in the future, and DELTA considers the demographic makeup of these populations when calculating nutrient requirements, because not all individuals have the same nutrient needs.

What are the results of the model?

In this paper, the DELTA Model was used to address a number of different questions.

Where are the gaps in our current food production system?

Using 2018 data, it was found that there was sufficient availability of most nutrients to feed the global population. The only exceptions were calcium and Vitamin E. There was even sufficient macronutrients (e.g. protein, energy, fat) to nourish the 2030 population. This demonstrates that the problems of undernutrition present in the world are partly due to the inequitable distribution of food.

What about food waste?

The DELTA Model found that even completely removing food waste doesn’t solve all our nutritional problems. There still wouldn’t be enough calcium or Vitamin E for the global population. This is because we waste different amounts of different nutrients, so reducing waste has a varied impact on nutrient availability.

Comparison between levels of waste for each nutrient considered by the DELTA Model in 2018. The bars show total nutrient waste and loss as a percentage of target daily intake. Nutrient waste is dominated by waste of plant foods, and varies greatly between nutrients.

What foods should we be producing in the future?

The DELTA Model wasn’t designed to be prescriptive, so no optimal food production system is given. Instead, a few example future scenarios are discussed, each of which fails to meet nutritional needs in some way.

Scaling up food supply with the population doesn’t resolve nutrient gaps, it just keeps them from growing any larger.

Removing meat and seafood production to achieve a globally vegetarian diet increases the food available to people due to reduced animal feed demand, but leaves gaps for key nutrients for which these foods are major contributors, such as iron, zinc and Vitamin B-12.

Increases in plant food production can help to feed a growing population, but using this technique alone to meet nutrient requirements may come with an excess intake of energy.

Finally, halving waste by 2050 is an admirable goal, but not the whole answer. Doing so would keep macronutrients above requirement, but would leave many micronutrient deficiencies.

What’s novel about DELTA?

There exist several other models for global nutrition which perform a similar role to DELTA (e.g. GENuS, The Global Nutrient Database, Beal et al.). The key points of difference and novelty in DELTA are:

  • Accessibility: few of the alternative models are openly available for the general public to use to gain a better understanding of global nutrition. Moreover, many of the alternative models use data that is not publicly accessible, making interpretation more challenging.
  • Bioavailability of nutrients: the DELTA Model takes into account the fact that 100g of a nutrient from one food is not the same as 100g of that nutrient from another food. For example, DELTA scales the availability of protein and the essential amino acids based on protein quality: the ability of the body to obtain and use these nutrients from different sources. The model also scales the iron and zinc requirements of the global population based on the foods available to meet these requirements. Consideration of bioavailability allows for a more realistic comparison between availability and requirement than is possible from considering content alone.
  • Inclusion of upper and lower safe intake levels for nutrients: we all know about recommended daily intakes for nutrients. However, many nutrients have additional reference values, such as for safe lower and upper intake levels. The DELTA Model displays these in addition to a target intake, to give the user more information about the adequacy of nutrient supply. For example, in several scenarios detailed in the paper, there is sufficient availability of most required nutrients. However, these scenarios also feature energy availability above the safe upper intake level, implying that obtaining the target levels of other nutrients in these scenarios may necessitate excess energy intake.

The future of the DELTA Model

The current DELTA Model has a number of limitations for the SNi team to address in the future. For example, the current version considers 29 nutrients, but this does not include all that are essential to good nutrition. Inclusion of essential fatty acids will be a key next step.

Bioavailability is currently only included for some of the nutrients in the model. This will be developed in the future, but is limited by the availability of data for all nutrients from all foods.

Future versions of the model will also need to calculate the environmental impacts of food system scenarios. At present, it is the user’s responsibility to decide whether their scenario is possible from an environmental perspective. We are currently working on land use sub-models, which will allow the user to see the required land necessary for food production in their scenario. Other environmental impacts will follow.

Under justified scrutiny from an environmental sustainability perspective, the global food system needs to change. However, it is essential that the nutritional implications of any change are not forgotten. The DELTA Model is a tool that allows us to investigate future food system scenarios to see what is possible from a nutrition perspective, to be considered alongside the other aspects of sustainability.

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All content relates to or was reproduced from Smith et al. (2021) Journal of Nutrition

Insects are in!

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While it may seem a rather squeamish topic, edible insects have been found to provide a healthy source of protein for humans. With a low environmental footprint, insect protein looks to be growing as a favourable alternative protein source for the future.

A recent paper in The American Journal of Clinical Nutrition has found that mealworms provide a high-quality protein source that matches that of milk protein. Through the use of isotope labelling, this research found that the nine essential amino acids in mealworm-derived protein had the same performance on digestion, absorption and stimulation of muscle growth as milk protein.

Milk protein is often considered the “gold standard” for protein quality, with plant-based proteins falling in behind due to their often-incomplete profile of amino acids and lower bioavailability. Although a rich nutrient source, milk is often criticised for its environmental footprint due to methane emissions, water use and quality, and agricultural land use change. Insects on the other hand can be reared at scale with minimal environmental impact, and according to the present study can provide a high-quality protein source for the human diet.

At present, the major non-food uses of insects are in animal feed and fertiliser. However, research like this and others (e.g. EFSA’s safety assessment, FAO paper on benefits of insect-based protein) along with significant market value growth indicates future development in this industry for human food is likely. To unlock the potential of edible insect-derived protein, the negative perceptions of eating insects in the Western World would need to be overcome.

This study highlights the promising benefits of mealworm as an environmentally friendly protein source for the human diet. However, milk provides more than just protein. Arguably more important than being a protein source, dairy foods are an important source of micronutrients often difficult to otherwise adequately source from our diets, including Vitamin B2 and B12, calcium and potassium. The use of milk as a comparison to novel protein sources is useful but before any conclusions can be formed around substitution potential, the entire nutrient profile of foods must be considered to determine other benefits exclusive of protein.

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The impact of transitions in animal production on nutrition

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Many parts of the developing world are transitioning from traditional animal-sourced foods to lower diversity, higher production animals. In parts of the Amazon, this includes transitions from capture fisheries to aquaculture and chicken production. These transitions are often supported by international development organisations to increase food security, but new research has examined what this transition means for human nutrition in a Peruvian population.

The authors found that increasing chicken production at the expense of capture fisheries increased the number of individuals who could meet their protein and zinc requirements, but decreased the number meeting iron, calcium and fatty acid requirements. These changes would be particularly impactful on young children and adult women due to their nutrient requirements. Similar, but less drastic changes, were found for the replacement of capture fisheries with aquaculture.

The authors make a number of recommendations looking to the future. Diversity of animal production and consumption should be maintained, as both the traditional and novel production systems have benefits for nutrition. Fishery protection to ensure continued availability of traditional food sources is a priority, as should be the production of diverse species in aquaculture systems.

The approach taken by these authors is similar to that of the DELTA Model, emphasising the need to consider the availability of all essential nutrients resulting from proposed changes to a food system.

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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.

Increasing the nutritional and environmental benefits of crops

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An integrated technique has been used to find the multiple benefits of introducing legumes to crop rotations in a recent Frontiers study. Not only are these promising findings for developing sustainable food systems, but also a step forward in holistic life cycle analysis measurement.

Adding legumes (beans, peas, lentils) to crop rotations has been shown to increase the nutritional value for livestock and humans while reducing environmental impacts and resource costs. In one example, introducing a legume crop into a typical rotation in Scotland reduced external nitrogen requirements by almost half, with no detriment to the crop’s human nutrient output.

The benefits of legumes range from environmental to nutritional. Unlike many other crops that require additional nitrogen to grow, legumes obtain sufficient nitrogen from the air around them without the need for additional fertilizers. This occurs through a symbiotic relationship with root bacteria that transforms nitrogen in the air to a useable form for plants. Legumes also reduce the need for fertiliser in future crops as they enrich the soil with nitrogen. In terms of human nutrition, legumes are rich in protein, fibre, folates, iron, potassium, magnesium and vitamins.

The novelty of this study was in its comprehensive comparisons across ten crop sequences, 16 impact categories, lengthy timeframes and various European locations. The authors went beyond simple footprinting techniques that only consider the environment or nutrition in isolation. Instead, they considered the footprint of delivering a specific quantity of nutrition. This provides a welcome and realistic perspective on the value of the whole system, with inter-crop effects and overall efficiency of cropping sequences considered.

This work has shown that the choice of functional unit has an important influence on the apparent efficiency of different crop rotations. It also indicates a need for further research using functional units that represent the multiple nutritional attributes of crops for livestock feed. The results of this study illustrate the benefit of using whole-system thinking when designing interventions to drive sustainable food systems.

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Climate change impacting our productivity gains

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Global efficiency in agricultural productivity has been known to increase over time, but a recent paper published in Nature Climate Change has illustrated the significant gains we have lost due to climate change.

Productivity growth can be understood as increasing the output of crops and livestock when using the same inputs. As concerns around food security and prices, input costs and the availability of resources grow, the idea of increasing agricultural productivity offers a more positive outlook for the development of the food system.

The Global Agricultural Productivity Report released in 2019 claimed agricultural productivity is growing at 1.63 percent globally. In order to see sustainable production of our food system and supply for a future population of 10 billion in 2050, they estimated that this productivity needs to increase to 1.73 percent.

The novel findings from the recent paper are the first to consider the historical trends and impact of climate change on agricultural productivity. Econometric models are combined with various climate scenarios to illustrate the impact climate change has had on agricultural productivity over the decades. The key finding is that the relationship of inputs and outputs have not been able to reach full potential in productivity gains due to climate change. This has been quantified at 21% of potential agricultural productivity being lost since 1961. This is equivalent to losing 7 years of productivity growth.

Our productivity gains are not currently enough to sustainably supply our growing population, and the scales are tipped further by the impact climate change has on our food production.

While it is disheartening to be confronted with further impacts that climate change is having on our food system, this research does provide tools to increase the robustness of future risk analysis with an increased understanding of climate change rates and impacts.

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DELTA Model version 1.3 launched

The coloured bar shows the global average availability of each nutrient. The error bars show the range in availability in different parts of the world (10th and 90th population percentiles based on country level averages). While there are only a couple of nutrients where global availability is below target, the level of variation results in many more nutrients of concern at a country level.

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The latest version of the DELTA Model is now available online. It features new insights into national and regional nutrient availability, as well as nutrient trade.

It’s common to talk about food trade between countries or regions, but less common to think about the movement of individual food nutrients around the world. For example, New Zealanders are probably very aware of our country’s exports of animal-sourced foods (like dairy and red meat), but likely haven’t thought about what this means in terms of the calcium or iron included in these exports.

DELTA 1.3 presents the domestic production of 29 food nutrients, the export and import dynamics of these nutrients, and how this measures up to meeting per capita per day nutrient targets for a country. It also presents how this availability differs in different parts of the world, showing the user the inequalities in access to different nutrients. The results are adjusted for waste, non-food uses and bioavailability in the same way as the rest of the DELTA calculations.

Another change is to the splash page first displayed to the user. This now features an outline of the global nutrition challenge that the world is facing, as well as a description of how the DELTA Model was designed to contribute to our understanding of this complex challenge. Further additions and changes can be found in the release notes.

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Bottom trawling dragging up more than just fish

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A recent paper in Nature includes evidence that bottom trawling releases more CO2 emissions from carbon stores in marine sediment than the entire aviation industry.

Similar to how our soils store carbon, our oceans stock the largest amount of carbon on the planet. The paper suggests a framework to prioritise protection areas of the ocean that would see multiple benefits. These include preserving biodiversity, increasing yield for fisheries and securing marine carbon stocks.

Marine sediment stores carbon, which is released during bottom trawling, a common practise of fisheries. According to the present study, this activity was estimated to release 1 gigaton of carbon every year. Comparatively, the aviation industry releases about 918 million tonnes. However, all is not doom and gloom, as the paper also identifies areas that would be most beneficial to protect. They calculated 90% of the carbon disturbance could be avoided through protecting only 4% of the ocean, although this comes at a cost of 27 million tonnes of fish. Level of benefit in biodiversity, carbon and food are illustrated in various conservation strategies, dependent on the value placed on these factors.

This is not to say we should all rush to the airport, nor does this suggest forgoing fish and chip Friday. Rather, our ever-expanding database on the impact of human activities is a reminder of the system view we must take when exploring what a ‘sustainable’ lifestyle may look like. The global food system is full of intricacies, and the impact some food products have on the world could far surpass what seems reasonable.

As our breadth of knowledge from these individual studies increase, as do our capabilities in modelling and drawing evidence-based insights on our global food system. By also suggesting beneficial protection areas, rather than exclusively focusing on the impacts of bottom trawling, this paper may spark conversation rather than accusation between the fisheries industry and marine conservation groups.

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Could regenerative agriculture offer a solution to a more sustainable food system?

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Regenerative agriculture is a hot topic after suggestions it offers a partial remedy to climate change. However, for a concept surrounded with such high expectation, there is very little clarity around the definition of regenerative agriculture or it’s evidence-based benefits. The National Science Challenge, Our Land and Water New Zealand have published a white paper calling for further clarity and scientific testing of claims.

The term regenerative agriculture identifies an approach to food and farming systems that originated in the US focusing on five farming principles that claim to regenerate the land, rather than degrade it as many conventional practices have been found to do. These principles are: minimise soil disruption, keep soils covered, plant diverse crops, reduce fertiliser use, and practise rotational grazing. This idea has been embraced by the general public, leaving agricultural sectors around the world challenged to apply it to their own unique systems.

In our hunger for a quick fix to climate change, many have jumped on the assumption that regenerative agriculture could be a farmer’s way out of the flack often received for agriculture’s impacts on the environment. However, this may be an overly optimistic stance to a challenge that far exceeds the implementation of a regenerative mindset.

The white paper comes from over 200 representatives of the New Zealand agriculture sector to determine the next steps for regenerative agriculture research. Some of the recommendations include:

  • There is a requirement for further evidence-based research and trials on the true benefits, both environmental and economic, of regenerative agriculture for the farmer and food producers by assessing marketability and export value.
  • Application of the term ‘regenerative agriculture’ differs between countries. Although the term was conceived in the US, the mindset can be applied to other countries as long as it is made relevant, i.e. bringing in cultural aspects and maximising what the land may already have – for New Zealand this can be focusing on retaining soil carbon levels while the US looks at increasing soil carbon.

If food and farming is to be truly regenerative then a framework based on validated science is required. In the meantime, perhaps the concept of regenerative agriculture can act as a reminder to farmers and consumers of the care and consideration our environment deserves.

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The life of your food: A discussion of LCAs

A low impact lifestyle has become desirable as the consequences of our excessive consumption are exposed. However, how do we assess the environmental impacts that our product choices have? Here, we discuss the use of life cycle analyses (LCAs) and the challenges and opportunities these pose in estimating the environmental impact of our food systems.

LCAs are an assessment method used to estimate the environmental impact of items over their lifetime. Such impacts can include water use, land use and greenhouse gas emissions (GHGs). When used correctly, they can be an effective comparative tool between similar items and highlight points in the value chain for improvement.

LCAs have a number of stages, and there are a range of types of LCA. Lifecycle inventories (LCIs) are first collected, which take account of all inputs and outputs within a system. This is followed by LCIAs (lifecycle impact assessment) where the impacts of LCIs are quantified and often differentiated into ecosystem impacts, human impacts and resource depletion. The commonly used term ‘footprint’ can represent a partial or full LCA, but only focuses on one aspect of the system. For example, a water footprint assesses the impact on water availability and quality across the entire life cycle of the product, but this would not include the impact on carbon emissions or land use.

LCAs are recognised as a useful impact assessment tool and as such have standardised methods set by ISO (International Organization for Standardisation). These guidelines have been interpreted differently throughout the literature, especially when applied to a system requiring the allocation of upstream products and inputs that serve in more than one system. For example, water used to irrigate rice paddies would form part of the water footprint of the rice. However, if the rice straw is also used as animal feed, how should the water footprint be allocated between the rice and animal production? Another issue with the methodology when applied to GHGs is that it typically only uses the GWP100 climate change metric, which can misinterpret short lived gas potentials e.g. methane. These limitations highlight the complexities of LCAs and the need for consistent methodology to improve the reliability of the assessment.

Using LCAs for the estimate of a product’s impact provides a landscape where the products can be compared. Although this can see misinterpretation, which will be discussed later, the complexities of this process can also offer up informative results for consumers and producers that may not seem obvious at first glance. This can be best used when comparing products that are similar in their final output (i.e. provide an equivalent user benefit), but may differ in their production chain e.g. competitor products, items produced in different regions and countries, or comparing similar products manufactured by the same company.

One product may have a variety of impact levels dependent on its origin, where it was purchased, right down to the practices of the individual farmer. Simple consumer choices may significantly decrease an individual’s impact. When choosing a discretionary food like chocolate, the choice of dark chocolate over milk or white chocolate significantly reduces the environmental impact. A difference in the nutritional composition of these products should be noted, although it is not a product we eat for its nutritional benefit. Furthermore, it has also been found using LCAs that a change to using 100% recyclables will result in minor reductions in an individual’s carbon footprint, and rather a focus on simply reducing consumption of packaging would see better results.

One of the most robust uses of LCAs is in the optimisation of company production lines. An internal LCA can pinpoint both the area with the most opportunity to reduce impact (e.g. manufacture, shipping, retail) or highlight one product having less impact than another, signifying its value for the company. Having numerical figures produced by LCAs can also provide tangible options for tracking improvements through regular analyses. For example, following its first LCA in 2009, Nespresso committed to reducing the carbon footprint of a cup of its coffee by 28% by 2020. Through these LCAs, Nespresso also investigated the impact between coffee systems to show the use of Nespresso was equal in carbon footprint with three other common coffee systems, while fully automated coffee systems had the highest carbon footprint. Not only does the direct product hold opportunity for more sustainable consumption choices; so too do the processes used to extract the coffee.

The benefits of the accurate use and awareness of LCAs go further than educating individuals or companies. As the literature on LCAs increases across a broader range of products, processes and end-of-life options, it allows consumers to make informed decisions in their quest for a truly low impact life. This also provides critical data to modelling platforms such as the DELTA Model.

With the complexities of LCAs comes the opportunity for misleading comparisons. This can be through comparing two products that have little similarity in characteristics, comparing different parts of the value chain (cradle-to-farmgate versus cradle-to-grave), or only using one footprint to pull conclusions on an item’s entire impact. These have led to some misconceptions, especially when inappropriately exploited by commercial interests to promote one product over another. For example, plant-based milks being touted by some as better for the environment than dairy.

The environmental impact of bovine milk has shown significant variation between different countries, right down to differences inter-regionally. This variation allows the impact assessment outputs to be picked in favour of marketing claims by competitors. When used to compare bovine milk to plant-based alternatives, LCAs can create oversimplified and misinterpreted conclusions such as assuming nutritional equivalence between products, or using global average impacts not representative of the variation between production systems. More appropriate use of LCAs in milk comparisons would be to compare plant-based milks with one another, or compare different farming systems and practises between countries.

This scenario exemplifies the potential misuse of the tool, and highlights a gap in the literature that LCAs are yet to fill when applied to delivery of nutrition. A focus has been placed on whole products and macronutrients, where LCAs give footprints per kg of product or, less commonly, per kg of protein. Micronutrients are yet to be explored and would be an instrumental addition when considering the entire impact of food. This has become even more critical as deficiencies in specific nutrients when feeding the global population have been suggested by the DELTA Model. This gap can be demonstrated in LCA comparisons of protein sources that claim protein powders are more efficient protein sources than cheeses, grains and beef when considering their environmental impacts. This study does not include the numerous micronutrients also received from the ‘less efficient’ protein sources.

Taking a holistic view, you could argue that given the interconnectivity of complex systems such as the food system, even seemingly unrelated factors can have indirect impacts on one another. LCAs can provide an excellent measurement tool when estimating the impact of products on individual environmental factors. However, the examples of misinterpretation and the opportunity for further research demonstrate how the application of LCAs can fall victim to tunnel vision when estimating a product’s true impact. This absence of a holistic view can produce results misleading for consumers. Narrow LCAs provide one piece of the puzzle and consideration should be made of the broader impacts the product has on our planet, our bank accounts, our health and our livelihoods.


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