Nutrition research using smartphone apps

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Tracking population dietary habits is notoriously difficult, from cohort recruitment to the patchy recollections of what someone ate 24 hours ago. A recent article in Nature Communications approached diet studies via a freely available smartphone app, allowing a large cohort to be assessed with minimal commitment from the participants.

Data from over a million app users, who added on average nine entries to their digital food record each day for an average 197 days, was matched up with demographic and location data to understand the consumption habits of a US cohort.

Their results matched existing knowledge on food environments and dietary habits: high income, higher education, high supermarket access and low fast-food access (the latter two determined by location), all correlated with lower BMI, higher fruit and vegetable consumption, and lower fast-food consumption. One exception was a slight association between high income and high BMI.

The authors also matched their location data to the predominant ethnic group, which was possible due to the zip code level resolution of the data. Again, these results reinforced existing data on the prevalence of consumption of specific foods, and the prevalence of obesity, but across a broader area than previously possible.

This paper shows the power of repurposing existing digitalised data for nutrition research. Such large, long-term, detailed sampling of the US cohort would have been extremely challenging without the availability of an already popular app. Moreover, the privacy of individuals was protected, and the app developers donated the data from the research, facilitating a more refined understanding of their nutrition.

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The true cost of food

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Many researchers have proposed scores and methods for reducing the nutritional value of foods down to a single number – as covered in a recent Thought for Food. A new method takes an approach rooted in population dietary intakes.

There are many challenges to this: which nutrients to include? How to weight components without introducing bias? A recent paper has avoided these issues by including all nutrients in the Australia and New Zealand Nutrient Reference Values, weighted by the degree to which the Australian population under- or overconsumes them.

The NRF-ai metric (Nutrient-Rich Food Index – adequate intake) means that foods containing under consumed nutrients like calcium, magnesium, vitamin B6 and zinc will receive higher scores than those containing the same amount of vitamin C or phosphorus, which are consumed at adequate levels by most of the population. Conversely, foods containing free sugars will be penalised, as intake of these is above recommendations in most populations.
The score can be made specific to age and gender groups, as the prevalence of deficiency for each nutrient varies between these groups. Ultimately, this leads to a metric that ranks a food item on its ability to address the nutritional needs of the population.

There are many applications for this metric for comparing foods. In the paper, the author considers the score per $ retail price, to understand the cost-effectiveness of a food for meeting nutritional needs. Per environmental impact examples are also given.

NRF-ai represents an unbiased approach to reducing the nutritional value of a food down to a single number. While this approach still loses information compared to the full nutritional composition, it is still valuable for comparisons between like products. A similar approach is applied by the DELTA Model® for the nutritional value of food items for meeting global nutrient requirements.

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Least cost nutrient adequate diets in NZ

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We previously described the results of a modelling study that found the least cost nutrient adequate diet in the USA came in at US$1.98, and the equivalent least cost plant-only diet was $3.61. The authors of that study have now repeated their work with New Zealand data, reaching similar conclusions.

Linear programming was combined with supermarket food price data, food composition data and adult nutrient requirement data to find daily diets that met all nutrient requirements, optimised for cost.

Similarly to the original USA study, the least cost diet contained both plant- and animal-sourced foods. At NZ$3.23, the price difference to the plant-only diet (NZ$4.34) was reduced compared to the USA results.

In both the NZ and USA diets, milk was a large contributor to nutrient targets in the least cost diet. A soy beverage was the largest contributor to both mass and cost in the plant-only diets. Eggs, legumes, and cabbage were also important in both country settings. While fish was present in the USA least cost diet, this was replaced with green mussels in NZ.

The relative changes to the price of animal-sourced foods before they became priced out of the least cost diet differed between the two settings. Milk was removed when its price was 2.2x current NZ retail price (compared to 8x in the USA study); eggs under price increases of 1.8 times (11.5x in the USA study); and meat items under price increases of 1-2x (3-5.5x in the USA study). In contrast, the mussels remained in the least cost diet even if ten times more expensive than current prices.

This work reinforces the conclusions of the original paper: plant- and animal-sourced foods contribute to affordable, nutritious diets, and it can be more expensive to achieve adequate nutrient intakes if restricted to plant foods alone. However, the reduced resilience of most of the animal-sourced foods to price increases in the NZ setting is reflective of the differing relative retail prices of food in the two countries, which the authors state may be reflective of the influence of government subsidies in the USA.

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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.


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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10-year high for global food prices

Earlier this year, the FAO reported the highest global food prices in a decade, driven by a collection of factors. The economics of the food system play an important role in sustainable nutrition, but can be challenging to understand or influence given the complex system that they operate in.

The FAO Food Price Index measures monthly changes in the international prices of a selection of food commodities. The index combines global price data for 23 widely traded food commodities, including cereals, dairy products, meat products, sugar, and a number of vegetable oils, weighted by the average export share of each commodity group. The resulting index score gives an indication of global trends in food prices.

The Food Price Index in October 2021 was up nearly a third on the previous year. This has been largely driven by cereals (22% year-on-year increase) and vegetable oils (reaching an all-time high). Dairy, meat, and sugar were also up 15-40% on 2020 index values.

Cereal use is forecast to slightly exceed production over the coming year, leading to a slight decrease in global cereal stocks and the resulting change in supply/demand ratio that influences price. The forecast also predicts record high levels of international cereal trade, at 478 million tonnes annually, out of a total 2.8 billion tonnes produced.

Changes in international food prices are driven by a variety of inter-related factors. Some recent factors include reduced harvests in major cereal and sugar producing regions, migrant labour shortages in vegetable oil producing countries, and increasing fuel prices.

The complex economics of the food system are challenging to unpick, but play a central role in the delivery of food and nutrition to the global population. It is important to consider the balance of input costs, output value and demand when thinking about the future global food system. Increased trade demand, reduced harvests and external costs all have an impact on retail food prices and availability, with implications for consumers. A sustainable food system must be holistically sustainable, and economic sustainability is a key part of this.


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Is lab-grown meat really all it steaks up to be?

The Good Food Institute recently commissioned a techno-economic analysis projecting the future costs of producing lab-grown meat, that has since seen backlash as lab-grown meat’s inevitability is put to question.

The report models the cost of producing lab-grown meat at industrial scale following various future scenarios to build a timeline out to 2030. The modelling illustrates diminishing costs from a current baseline using data from 15 companies in this field. Currently, production prices are over US$22,000 per kg of product. If significant technical and economic barriers were addressed, the report estimated the cost could drop to $6.43 per kg in 2030. The report provides a positive outlook on the future of lab-cultivated food products being economically accessible and technologically viable.

This has seen backlash by experts in the fields of biotechnology and economics. Overcoming the barriers required to scale-up this technology and realising the stated cost reductions have been labelled as “very theoretical”, over-reaching biological limits, and underestimating the costs involved. For example, it would cost an estimated $1.8 trillion to build the facilities required to produce even 10% of the current meat supply.

These findings exemplify the caution that must be taken when considering media articles and the claims of biotech start-ups, projecting a future and timeline for lab-grown meat that drives interest in the technology. Although these technologically-derived products may support a sustainable food system in the future, the significant challenges this sector faces indicate that we must focus on the efficient use of current resources today, without relying on the future potential of such technologies.


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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 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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Changes to diet can be a win-win for nutrition and environment, but not all changes

Individuals are increasingly concerned about the environmental impacts of their food choices. A recent paper in Sustainability quantifies the global warming impact of several NZ diets over the entire lifetime of the consumer, providing context for the role of diet in an individual’s overall contribution to global warming.

How can we eat healthier diets that still satisfy us, which don’t cause excessive damage to the environment, without breaking the bank? Questions like this have arisen in the minds of most conscientious consumers at some stage, but there is little consensus on what such a diet might look like in the nutrition field.

Prioritising any factor – health, taste, price, or environmental impact – depends on the values of the individual. However, when we fail to adequately consider health and nutrition, the risk to the individual is high.

On this topic, the Riddet Institute’s Sustainable Nutrition Initiative team were recently involved in a multi-organisation international project calculating the global warming impact of various New Zealand diets.

The research took the current average NZ diet and calculated what the global warming impact of this diet would be. In a point of difference to much other work in the field, the cumulative warming impact was calculated over the entire lifetime of an individual, rather than shorter term impacts. The calculation was repeated for a NZ diet that follows the national dietary guidelines, and a vegetarian NZ diet with no meat content. Each was designed to reflect realistic choices that a NZ consumer might make.

The results show that a move from the average diet to one that adheres to the NZ dietary guidelines would have benefits both to nutrition and global warming impact. Similar results have been found in many other studies (see here, here, and here), so this was not surprising. In this research, the reduction in the global warming impact of the dietary guidelines diet was 7-9% compared to the current average diet.

Transitioning to the no meat diet showed a reduction of 12-15% in the global warming impact of the diet compared to the average NZ diet, so an additional reduction of 3-8% compared to the dietary guidelines diet. However, in the context of an individual’s total warming impact from all consumption (i.e. including things like transport and heating), switching to the no meat diet at age 25 was calculated to result in a 2-4% reduction overall. This relatively small result is because diet is only one part of our global warming impact, accounting for about a quarter of consumption-based emissions for the average New Zealander. As a comparison, transport is on average around 35% of NZ consumption-based emissions.

Consumption-based emissions differ to production-based emissions. Production-based emissions are those produced within a country, without accounting for how goods are traded across the world. Consumption-based emissions take account of the trade of goods, allocating emissions to the end user based on the products they consume. This choice is particularly important in countries like NZ, which export and import large proportions of the food they produce and consume.

Bringing in the cost side, other NZ research has also shown that dietary guidelines, flexitarian and vegan diets can have reduced greenhouse gas emissions, but that the price also rises as the diet moves further from the current average NZ diet. Thus, such changes will be less achievable for individuals with less to spend on their food.

Clearly, there are a number of ways that concerned individuals can reduce their warming impact, such as changes to transport, heating and recreational choices. Diet is one of these options, but these choices must be evaluated on their efficacy.

This research is important in providing context for the contribution of diet to an individual’s global warming footprint. Most importantly, a transition towards the recommendations of the dietary guidelines was a win-win for both nutrition and global warming footprint.

However, in the context of an individual’s overall lifetime global warming impact, it is important to realise that changes to diet made only a minor difference.

The NZ context of this work is also influential. Over 80% of NZ electricity generation is from renewable sources, which reduces the global warming impact of the NZ energy sector. As such, many activities in NZ (such as heating or manufacturing) have a lower warming impact than they would in other parts of the world. Similarly, many parts of the NZ agriculture sector have lower carbon emissions per kg of product than seen in other parts of the world. Therefore, the percentages above are likely to differ in different parts of the world.

A key takeaway emphasised by this research is the need to prioritise considerations of nutrition and health when thinking about our own diets. One of the important things to note from this paper is that the diets considered were not nutritionally equivalent. Moving from the average NZ diet to the dietary guidelines diet largely meant increasing fruit and vegetable content and reducing discretionary foods. There were some smaller increases in certain dairy products and decreases in some meat products. The result was a diet with improved availability of calcium, fibre, folate, and magnesium.

The no meat diet was not equally win-win: while it had a reduced warming footprint and was broadly similar in its nutrient availability to the dietary guidelines diet, its iron content fell short of the average adult’s daily requirement.

The nutrient differences are more pertinent to consumers than the small calculated global warming impact. Changes to the foods in an individual’s diet result in changes to the amount and sources of the nutrients they consume. It is essential that, when considering changes to diet motivated by external factors such as global warming impact, individuals are aware of the nutritional changes they will also be making. These changes may have large positive or negative impacts on health and wellbeing.

Adequately nourishing the global population is a key component of sustainability. A food system that does not deliver nutritious diets to all cannot be considered sustainable, regardless of its social, economic or environmental sustainability. It is essential that, when we are considering the environmental aspects of diet, such as the lifetime global warming impacts (as calculated in this paper), that we do not ignore the nutritional adequacy of different diets.


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