The requirement for balanced global diets that connect 9 billion consumers


Wayne Martindale, Associate Professor of Food Insights and Sustainability at the University of Lincoln, provides a perspective on sustainable diets and how we should think about them.

The food and beverage system functions globally; we all source our meals from a global marketplace. The responsibility for a nutritious and balanced diet begins with producers and manufacturers before it is presented to consumers. The flow of foods and ingredients in the global food system provides many surprises.  

This article is a viewpoint from Europe and the United Kingdom, where our nation is soon to realise the impact of globally sourcing our food. Sustainability and security are inseparable attributes here and we believe a sustainable diet must provide balanced nutrition and security. This article will develop this relationship using existing evidence and demonstrate that limiting the discussion to a single attribute of sustainability such as greenhouse gas emissions, biodiversity or land use change will only result in polarised debates that will never get us to where we need to be. 

Best practice in the food and beverage industry has been transformed by sustainability. It resonates across industry and consumers as an ideal we should rightly strive to achieve. Much of what we have been aiming for is to reduce the greenhouse gas emissions associated with the production and consumption of foods. Manufacturers are now reporting carbon zero product categories including whole milk and beef, which was unthinkable ten years ago. Our improved understanding of how resources flow through food systems has made carbon zero a reality. Programmes that sought to reduce greenhouse gas emissions ten years ago exposed many gaps in our understanding of food systems.  

The initial debates tended to demonise food and beverage products with higher carbon footprints – namely livestock products and beef (Cederberg et al., 2011). What these studies did not consider was nutritional delivery and consumer experience, both of which are important because without them sustainability will never be delivered (Haddad, 2018). This is because every meal must deliver balanced nutrition and a favourable experience. If it does these two things, it is more likely it will result in optimal health and not be wasted. I was working with CSIRO in Melbourne as a McMaster Fellow when I realised that these relationships were critical. This was in part due to the publication of the Total Well Being Diet (TWD) book by CSIRO (Noakes and Clifton, 2005). What influenced me here was the fact that a formalised and scientifically formulated diet for health – the TWD – could resonate so strongly with consumers that a Government Science Agency publication on dietary change became a best seller! In the UK, this was only achieved by our best celebrity chefs, with the science part often in second place for editorial decision making. The TWD demonstrated the requirement for a healthy diet is clearly resonant with consumers. The notion of what is a sustainable one was less so, but it raised the issue of whether the two are related in any way? 

The issue of sustainability in food has often been associated with carbon footprint. The first studies of crop and livestock production that calculated what we now recognise as a carbon footprint were reported over 20 years ago (Brentrup et al., 2000). These were transformative in that they identified production processes that could reduce greenhouse gas emissions. In the case of agricultural products, their application resulted in reductions in diesel and fertiliser nitrogen used in sustainable farming.  

However, in terms of guiding responsible consumption, carbon footprints can be cumbersome. Such direct measures of carbon footprints for food lead to comparing livestock and plant proteins without considering any dietary requirements. Consumers are often told to not eat specific products, with beef being the main target for such attacks. This leads to a ‘stand-off’ in the sustainability arena, stifling innovation in manufacturing. Nutrition, consumer experience and taste all play an important role in quantifying what is sustainable, and they need to be accounted for when we place carbon footprinting into diets, meals and lifestyles. 

Carbon zero thinking has been transformative in breaking this deadlock and the launch of branded zero carbon livestock products such as whole milk, beef and lamb have shown that food producers and manufacturers are confident in claiming it (read more here). The subsequent re-thinking of carbon footprinting is enlightening because it can be related to achievable and nutritious diets and lifestyles so that responsible consumption is possible.  

Plant products typically have a lower carbon footprint than livestock products. Converting plant protein into livestock protein as efficiently as possible often means an increased carbon footprint. But even here there are exceptions. For example, rice has a greater footprint than whole milk (Clune et al., 2017). This is because of the requirement to flood and drain the soils used to grow rice, resulting in methane emissions (Burney et al., 2010). 

Consideration of production volume can provide a transformative view of the global food system carbon footprint. Production of the ‘big four global commodity crops’: rice (0.7 billion tonnes per year), wheat (0.7 Bn t/yr), maize (1.0 Bn t/yr) and soy bean (0.3 Bn t/yr) account for around 2.8 billion tonnes of production each year (Clune et al., 2017). Three of these crops have a carbon footprint of 0.5 tonnes CO2-equivalent per tonne production, and rice has 2.6 tCO2-e/t, summing to 2.8 Billion tCO2-e associated with the big four each year. The mean or average carbon footprint for beef globally is around 25 tCO2-e/t, some 50 times that of wheat, maize and soybean crops, used for both feed and food. However, only 64 million tonnes of beef are produced globally each year, which accounts for some 1.5 Bn tCO2-e. The GHG ratio of the ‘big three’ (‘big four’ excluding rice) to beef is therefore not 50 but 1.5! If we include rice, beef has half the global carbon footprint of the big four crops. This means we are being mis-led by slavishly following carbon footprint data alone. 

There is also much more here, in that a number of studies on beef for the reported average carbon footprint include the prime production of Wagyu beef under extremely intensive conditions (beer and massages) that holds no resemblance to grass fed and finished beef systems including typical Wagyu systems. The issue of production volume together with variation in carbon footprint data is overlooked in simplistic carbon footprint assessments. If we include variation in livestock production systems, the idea of a typical carbon footprint becomes unrealistic at best! Moreover, the spotlighting effect of carbon footprint will often leave the issue of nutrition aside and this is another reason there is a requirement to look at how carbon footprints of food are measured.

If we were to eat the lowest carbon footprint food group per calorie it would be cake and confectionery alone, because these foods have a carbon footprint of around 80 gCO2-e/100 kcal, whereas fruit and vegetables produce over 400 gCO2-e/100 kcal (Drewnowski et al., 2014). This is surely the opposite to what we are told as consumers. Milk and dairy products are in the middle of this range, lower than meat. And this is only considering calories; considering other essential nutrients such as protein would likely paint a different picture again. The dietary context for carbon footprint clearly needs to be clarified and that is why the Sustainable Nutrition Initiative seeks to find methods of providing robust evidence that will guide realistic, sustainable consumption that provides good health. 

An improved ability to access data has brought energy balance and carbon footprinting into the consumer goods arena and the drive for carbon zero is creating much innovation in food and beverage. It has brought sustainability closer to the consumer in that the consumption of a nutritionally balanced diet can be delivered sustainably even if we do not choose or eat food based on carbon footprints.  

It is important that improvements do not get lost in purely carbon footprinting diets. We are developing models for the UK that identify where critical points and connectivity in the food system control resource flows (Martindale, Duong, et al., 2020). These can be integrated with the nutritional insights of the DELTA Model developed by the Sustainable Nutrition Initiative and build on established indices of food sustainability. New Product Development (NPD) is the operational activity we are focusing on because, if product developers and technologists build in sustainability at the concept stages, there is an increased possibility that the final product will deliver it (Jagtap and Duong, 2019). One of our models – Centreplate – is currently being tested with respect to NPD strategies, improving protein supply and reducing waste (Martindale, Swainson, et al., 2020).  

We are currently at a point where food system insights have the potential to bring sustainability and nutritional datasets together because of two technological advances we would consider most notable. The first is the ability to embed digital technologies into resource packaging so that traceability and analysis of supply chain data can be enabled securely for most food companies (Martindale et al., 2018). The other is the projection of dietary impact of nutrition on populations. This changed forever a generation ago in response to the newly sequenced human genome. What followed was a scramble for therapeutics but the interaction of health and nutrition through our diet was largely overlooked (King et al., 2017). We now have a greater understanding of how genes and metabolism interact with what we choose to eat. It is essential to keep the food system lens, and this is what the Sustainable Nutrition Initiative’s DELTA Model does. Connecting datasets and making sure we speak to each other is becoming increasingly important. This is otherwise known as interoperability in the digital arenas. We have the capability to deliver a net zero sustainable food system, but without interoperability it will not happen. 

Our food future depends on all partners in the global system connecting methods and data that will guide sustainable dietary choices. At present the sustainable diet arena is noisy and confusing for many consumers because polarised views can dominate. This is why actions such as the Sustainable Nutrition Initiative are so important; they lay bare facts and guide routes to sustainable and secure global consumption that still provide the choice and experience that consumers require.

Wayne Martindale directs the Food Insights and Sustainability Service at the National Centre for Food Manufacturing at the University of Lincoln. Wayne has been working in sustainability since 1998, after eight years of doctoral research in biochemistry in the UK, Japan and USA. He started his sustainability practice with the BASIS/FACTS leadership team delivering certification programmes for UK agriculture and has held visiting scientist roles at CSIRO Australia and the OECD in Paris.


Glossary

Photo courtesy of Wayne Martindale.

World Food Day

Our Actions are our Future: Grow, Nourish, Sustain. Together.

Today – Friday 16th October – is World Food Day, the 75th anniversary of the founding of the Food and Agriculture Organisation of the United Nations with its goal to achieve food security for all and make sure that people have regular access to enough high-quality food to lead active, healthy lives. We congratulate the FAO on reaching this anniversary and all the good work the organisation does.

At the same time, it is a day for all of us to reflect on the challenges facing the global food system. Despite advances in agricultural production methods and yields, we fail to produce and distribute sufficient food to nourish an increasing global population. Many production systems are damaging the natural resources on which they or other food production systems rely, and many food producers receive subsistence income from their products. The 2030 Sustainable Development Goal (SDG) of Zero Hunger looks as far away today as it did when the SDGs were first developed. 

Sobering facts from the FAO’s World Food Day 2020 webpage:

  • Over 2 billion people do not have regular access to safe, nutritious and sufficient food whilst the global population is still growing and expected to reach almost 10 billion by 2050. 
  • Nearly 690 million people are hungry, up 10 million since 2019. The COVID-19 pandemic could add between 83-132 million people to this number. 
  • The impact of malnutrition in all its forms – undernutrition, micronutrient deficiencies, as well as overweight and obesity – on the global economy is estimated at USD 3.5 trillion per year. 
  • Today, only nine plant species account for 66% of total crop production, despite the fact that there are at least 30,000 edible plants. We need to grow a greater variety of foods to better nourish people and sustain the planet. 
  • Approximately 14% of food produced for human consumption is lost each year between the “farm” and the wholesale market. Even more food is wasted at the retail food and consumer stages. 

Our ability to effectively nourish an increasing global population is one of the key challenges facing the human race. The global food system is incredibly complex, the world’s largest economic sector, with multiple inputs and outputs. It is often politicised, is subject to various socio-cultural forces, and touches every human being on the planet. Charting a course for the food system of the future requires quality thinking and discussion built on strong evidence-based foundations.   

The Sustainable Nutrition Initiative was founded to meaningfully contribute to this discussion.  Some key thoughts as we consider the future of food:   

The DELTA Model has been developed to help people explore different futures for the food system for themselves. 

The goal remains to achieve food security for all and make sure that people have regular access to enough high-quality food to lead active, healthy lives. We can all help towards this through understanding the food system in all its complexity, strengths, and weaknesses, leading to better informed discussion on the future of food for all of us. 


Glossary

Image from FAO World Food Day 2020 website

Protein: we need quality, not just quantity


Getting enough protein in our diets is essential for adequate nutrition. What is less well known is that protein represents a group of nutrients, the amino acids, each of which needs to be consumed in sufficient amounts. Here, we look at how we digest protein, the importance of amino acids, and show that protein quality, not just quantity, is vital.

Protein, alongside carbohydrates and fat, is one of the dietary macronutrients found on the nutrition label of all commercially-produced food. The recommended daily intake (RDI) for protein on these labels varies between authorities, but is usually around 50 g. This allows food companies to easily calculate and display on packaging what percentage of your protein RDI is supplied by their product.

But what is meant by ‘protein’ on these labels? And where do these RDIs come from?

Protein and amino acids

Proteins are a group of molecules essential to all life, distinguishable from carbohydrates and fats by containing nitrogen. The use of proteins in our bodies is broad: they form our tendons and ligaments as collagen, break down our food as digestive enzymes, and protect from infection as antibodies, among many other roles.

Every protein is composed of a string of smaller molecules, amino acids, folded into a functional shape. The amino acids in the string and the folded shape of the protein are specific to the function of that protein.

When we discuss protein as a dietary macronutrient, we are really referring to the supply of amino acids in the foods we eat, rather than the protein per se. The protein content seen on food packaging should really be seen as the sum of the amounts of each amino acid in the food.

Protein digestion and use

Protein is present in the majority of foods we eat. The amount and type of protein varies depending on the food, but all are subjected to the same digestive processes once eaten.

Protein digestion begins in the stomach. The body produces the enzyme pepsin, which starts the breakdown of proteins with the help of the stomach’s acidic conditions. Digestion continues in the small intestine, with the enzymes trypsin and chymotrypsin continuing the breakdown of proteins to individual or very short strings of amino acids (dipeptides and tripeptides).

These small molecules, rather than the original proteins, are absorbed by the intestine and transported around the body in the bloodstream. Once absorbed, amino acids are used to construct the many proteins needed by the body.

Consuming adequate protein in the diet is essential. Our bodies do not store protein in the way we can store fat or carbohydrates. Instead, there is a constant cycling of protein construction, breakdown and excretion. This protein turnover cycle leads to around 250 grams of new protein being produced each day, either using recycled amino acids from body protein breakdown, or from the amino acids derived from newly digested dietary protein. If dietary protein is lacking, this can lead to an overall depletion of body protein over time.

The importance of each amino acid

The most common way of calculating protein RDI is by bodyweight. For example, a frequently heard recommendation is that you should eat 0.8 g of protein each day for each kg of bodyweight. Thus, a 75 kg man should consume 0.8 x 75 = 60 g of protein each day. However, there is a lack of consensus around the value of 0.8 g, with many arguing that intake should be at least 1 g, particularly for athletes and older adults.

This calculation around protein RDI hides the more specific amino acid requirements of the body. There are 20 common amino acids, 9 of which are essential. Essential means that the body cannot effectively make these amino acids itself, so must obtain them from the diet.

There are RDIs for each essential amino acid, based on the amount required for body protein production. However, these RDIs are not displayed on food products, as this would be difficult to calculate for each food and make understanding nutrition labels more difficult. Instead, the protein RDI approximates what is needed based on the amino acid content of an average diet. This approximation was designed for a population that consumes a diverse diet over time. It is less fitting for day-to-day protein consumption of the individual, particularly those who consume only a limited range of protein sources. As an individual, it’s important you obtain enough of each essential amino acid each day.

What happens if we don’t get enough of a certain amino acid?

The result of deficiency in amino acids is best explained through an analogy.

Imagine you are assembling toy cars. The process involves painting the body of the car green, and then putting on the wheels. You have a box of car bodies, a pot of green paint, and a box of wheels.

As you are assembling these cars, you come to a point where you still have car bodies and wheels, but you have run out of green paint. However, with a little more effort, you can make more green paint by mixing some blue and yellow paint you have. With this newly made green paint, the assembly process can continue.

However, if you come to a point where you have car bodies and paint, but have run out of wheels, you cannot continue to assemble the cars. No matter how much of the other two components you have, the wheels are essential, so car assembly must stop until you have more wheels.

The construction of the toy cars from components is analogous to the construction of a protein in the body from individual amino acids. In the assembly of a protein, several different amino acids are required. Like the green paint, if the body runs out of a non-essential amino acid, then it can produce more from other amino acids, although less efficiently. However, if the body runs out of an essential amino acid (those that must be derived from the diet), protein synthesis is halted – much like running out of wheels in the toy car assembly.

If you do not obtain sufficient essential amino acids from your diet, synthesis of necessary proteins can be halted. The wheels in the toy car analogy are the ‘first limiting’ component in car assembly. In humans, it is often the amino acid lysine that is the first limiting amino acid to protein synthesis. This is because lysine is required in a large number of proteins and is not always readily available from the diet. A person can be protein deficient by being deficient in just one essential amino acid, regardless of the amount of the other amino acids they consume. And since the body is unable to store protein, an excess of unused amino acids consumed will be wasted by the body when it cannot immediately use them. Getting enough of each essential amino acid is required for optimal health.

How do I ensure I get enough of each amino acid?

Different foods contain different distributions of amino acids. For example, chickpeas are higher in lysine than oats, but the reverse is true for the amino acid cysteine. Plant foods are more often limited in certain essential amino acids than animal foods, due to the similar proteins required by animals and our own bodies. If plant-sourced foods are your main source of protein, it is important to understand their amino acid profile. Plant foods with complementary amino acid profiles can be consumed together to make up for their individual deficiencies.

Another important consideration is amino acid bioavailability; the percentage of the total amino acid that is available to the body from different food protein sources. The efficiency of the protein digestion process varies depending on the structure of the protein consumed and the food matrix proteins are contained in. Extensive research has been performed on the bioavailability of each amino acid in human foods. The table below gives a summary of bioavailability values for some selected foods.

FoodAmino acid bioavailability
(% of total consumption that is absorbed)
Roasted beef94 – 99  
Fish81 – 94
Cooked kidney beans64 – 100
Oats70 – 88
Potatoes47 – 66
Rice75 – 99
Skim milk78 – 97
Cooked soyabeans71 – 90

Bioavailability of amino acids can vary widely between foods. Therefore, it is useful to have a score for each food reflective of the overall amino acid availability, commonly referred to as protein quality. The DIAAS score (Digestible Indispensable Amino Acid Score) is recommended by the UN Food and Agriculture Organisation for this purpose. The digestibility of each essential amino acid in a food is calculated and compared to a reference protein, and the DIAAS is the lowest of these calculated values. The score is thus reflective of the digestibility of the most limiting essential amino acids in the food.

A DIAAS score of 100 or more indicates excellent protein quality, with high digestibility of all the essential amino acids. Scores between 75 and 100 are considered good sources of protein, but consuming complementary proteins would improve their profile. Scores below 75 are of lower quality. Some example foods with their DIAAS are given below.

FoodDIAASLimiting amino acid(s)
Beef (roasted)99Leucine and Valine
Pea protein concentrate82Methionine and Cysteine
Rice (cooked)60Lysine
Skim milk powder105Methionine and Cysteine
Soya protein isolate84Methionine and Cysteine
Wheat45Lysine

Generally, animal-sourced foods have higher DIAAS scores than plant-sourced foods. This means that the profile of amino acids is better suited to human digestion and to fulfilling our needs for protein synthesis.

At a global scale, producing enough of each amino acid is critical to the ability of the food system to meet nutrient needs. When considering possible future scenarios, the DELTA Model predicts the supply and bioavailability of essential amino acids, as well as total protein.

Take home message

The single macronutrient protein consists of a group of essential nutrients: the amino acids. These molecules are what is needed in our diet to construct the diverse body proteins, essential to bodily function, health and life.

Getting enough protein in your diet is not just about reaching the protein RDI. Instead, you need to reach the RDI for each essential amino acid. This is most easily achieved by eating high-quality protein, or combinations of protein sources with complementary amino acid contents.


Glossary

References for DIAAS values: 1, 2, 3, 4

Green car photo by MW on Pixabay. All other photos courtesy of the Riddet Institute.

Higher atmospheric CO2 changes the nutritional quality of vegetables

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Vegetables grown at higher carbon dioxide (CO2) concentrations may grow better but may not have the same nutritional benefits. 

Increasing atmospheric CO2 concentrations have prompted research into the effect of this phenomenon on plant growth. In general, elevated COis good for plant growth, increasing yield and environmental stress tolerance. However, a review of the research in this field has found that elevated CO2 also reduces the magnesium, iron and zinc content of vegetables. This reduction was as much as 31% for iron in leafy greens. 

In specific vegetables, the review found that sugar content of lettuce, tomatoes and potatoes increased at higher atmospheric CO2 concentrations, while protein content decreased. Other factors, such as antioxidant content, were strongly affected, but this effect was different between different vegetable cultivars. 

Higher yields with lower protein content have also been found for staple crops and grains grown at elevated CO2 concentrations. These changes occurred alongside reduced iron and zinc content. 

In a future with increased atmospheric CO2 concentrations, our crops and vegetables may grow larger and sweeter, but the amounts of other essential nutrients that we get from them may decrease. This could lead to higher caloric intakes required to obtain the same amount of nutrients from these foods. While the concentrations reviewed in this publication were high compared to those expected in the near future, we should be prepared for some degree of impact on our crops. Targeting crop varieties which make the best of the changing conditions is being explored.

Read the article


Glossary

Photo by Sharon Pittaway on Unsplash