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.
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 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.
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.
Amino acid bioavailability (% of total consumption that is absorbed)
94 – 99
81 – 94
Cooked kidney beans
64 – 100
70 – 88
47 – 66
75 – 99
78 – 97
71 – 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.
Limiting amino acid(s)
Leucine and Valine
Pea protein concentrate
Methionine and Cysteine
Skim milk powder
Methionine and Cysteine
Soya protein isolate
Methionine and Cysteine
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.
It is commonly heard that high consumption of sugar is linked to obesity, type 2 diabetes and other life-threatening diseases. However, a less discussed problem comes from the fact that sugar displaces more nutrient-rich foods in the food system and in individual diets.
The DELTA Model shows that based on all food currently produced, there is sufficient energy and macro-nutrients to meet the nutrient requirements of the global population – assuming that all food were distributed evenly. However, shortages lie in key micro-nutrients and trace elements such as iron, calcium and zinc. This creates a challenge to meet nutrient requirements without a problematic excess of calories, and within planetary resource constraints.
Because sugar supplies us with energy and carbohydrates, but little else, it provides minimal nutritional value. The most important aspect of a sustainable food system is that it must meet the nutrient requirements of the population. It can therefore be claimed that sugar is unsustainable in the fact it does very little to meet this requirement. According to the FAO, approximately 2.4 billion tonnes of raw sugar cane and beet is produced per year. This is nearly a quarter of the total food biomass from the world’s farms and oceans, and utilises 31 million hectares of land. This land could instead be used to produce more nutrient-rich foods like pulses, which are high in vitamins and minerals such as zinc, iron and folate.
On a more individual level, poor choice or lack of choice can lead to an excess of calorie-dense and nutrient-poor foods, such as those high in sugar. If this displaces nutrient-rich foods, ‘hidden hunger’ or micro-nutrient deficiencies can arise, despite the individual eating sufficient calories. It would be unrealistic to believe you could remove sugar from the food system altogether – some sugar and sugar derived production will be needed. However, sugar and other energy-rich and nutrient-poor foods should be prioritised as a target for reduction.
The North American Society for Paediatric Gastroenterology, Hepatology, and Nutrition (NASPGHAN) has released a nutritional position paper highlighting the deleterious effects of using plant-based alternatives to milk on infant development and health.
There are many of beverage choices available to Western consumers. These include plant-based products that are positioned as alternatives to milk. Influenced by trends such as ‘plant-based’ or ‘animal free’ and with perceived health benefits associated with the name ingredient, sales of these products have seen rapid growth.
The consumption of plant-based beverages is a matter of consumer choice and preference, appropriate in a diet that contains a balance of nutrients. However, problems arise when they are used as a replacement for dairy in cases where milk is the primary source of nutrition: for infants and young children.
By association and with the use of dairy terms, plant-based beverages leverage the nutritional credentials of milk. This leads consumers to believe they are getting (or providing for their children) a nutritional equivalent to milk, but in a healthier way, or with a lower carbon footprint, due to the perceived halo of plant-based products. However, this is often not the case. Many plant-based alternatives fall well short of dairy nutrient content, without considering differences in the bioavailability of nutrients between plant and animal sources.
The paper puts emphasis on protein, which is particularly important in the growth of young children. Due to a combination of low protein content and poor protein quality, one serve of almond or rice beverage may provide only 2% or 8% of the dietary protein of an equal sized serve of cows’ milk, respectively. The paper also recommends bioavailability studies for products that have been fortified to match other nutritional characteristics of milk (e.g. calcium).
The paper makes clear the need for consumer education to ensure that children are given the right foods for their nutrient needs.
Many countries across the world instituted a degree of lockdown this year to minimise the harm caused by the COVID-19 pandemic – but what effect does a lockdown have on nutrition and sustainable food production?
The impact of the Spanish lockdown during March and April 2020 on nutrition has recently been investigated by researchers from multiple Spanish and international universities. They found that the amount of food purchased increased slightly during the lockdown (from 13.8 to 14.3 kg per person per week). Plant foods were the major part of the increase, followed by eggs and red meat. Beer and coffee purchasing decreased, possibly due to the closing of restaurants and bars.
Food energy intake increased by 6% during the lockdown compared to the same period in previous years, while the nutritional quality of the lockdown diet was 5% lower. The environmental footprint of the lockdown diet was also greater than pre-lockdown: increases were found for water use, land use and global warming potential.
While this study only considered the impact of the Spanish lockdown, the trends are likely to be true for lockdowns in many countries. The results of this research highlight that changes to the global food system must take into consideration the potential for unexpected events to disrupt progress towards sustainable nutrition.
Consultative Group on International Agricultural Research (CGIAR) have been developing and implementing biofortified crops to address micro-nutrient deficiencies.
Deficiencies in micro-nutrients poses serious and widespread threats to health and economic development. This is known as ‘hidden hunger’. The conventional response has been supplementation or food fortification. However, these solutions involve high and recurrent costs, can be hard to organize in poor rural areas, and cannot always solve the problems. CGIAR scientists proposed that the same health impacts could be achieved by breeding vitamins and minerals into the staple crops that people eat every day, such as sweet potato, wheat and rice. This is known as ‘biofortification’. CGIAR have been working on this for almost 25 years and invested $900m into development and implementation. More than 290 new varieties of 12 biofortified crops have been released or are in testing. This has benefited 10 million farming households globally to date.
The DELTA model can be used to scenario test various food systems with the view of adequate sustainable nutrition for the global population. This repeatedly demonstrates that on a global scale, animal-sourced foods are needed to meet nutrient requirements. However, this is based on the fact that current conventional crops do not have the same content of bioavailable micro-nutrients and trace elements that animal-sourced foods do. There may be potential for biofortified plants to better contribute to global nourishment and reduce requirements for animal foods. However, what is still unclear is whether those micro-nutrients in biofortified plant-based foods would have the enhanced bioavailability that characterises animal-sourced foods. In addition, biofortified plant-based foods may not have the ability to enhance the uptake of micro-nutrients from plant-derived sources, in the same way animal foods do as part of a meal. For example, haem iron from meat helps with the uptake of non-haem iron from plant sources. The ability of biofortified plants to do the same needs to be determined before concluding that biofortified crops can replace the role of animal foods in the global food system.
Researchers at the University of Minnesota and Oxford University compared the environmental effects against the noncommunicable disease risk of certain food products.
It was found that foods associated with improved health outcomes; whole grain cereals, fruits, vegetables, legumes, nuts and olive oil, had amongst the lowest environmental impacts. In contrast, foods associated with the largest negative environmental impacts—unprocessed and processed red meat—were associated with the largest increases in disease risk. Chicken, dairy products, eggs, and refined grains had no significant impacts on either disease risk or environmental metrics. The report concluded that dietary transitions towards greater consumption of healthier foods would generally improve environmental sustainability.
These findings could help consumers, policy makers, and food companies to better understand the multiple health and environmental implications of food choices. However, this study looked at non-communicable disease incidence only, and did not address many other factors, not the least of which are nutrient deficiencies and the impact of nutrition on child development. For example, red meat plays a key role in the contribution to global requirements for multiple micro-nutrients such as iron, zinc and vitamin B12.
In addition, not all research agrees with the findings of this study. The Global Burden of Disease study found that a diet high in red and processed meat had very little impact on the risk of death or disability-adjusted life years. Diets low in healthy foods such as fruits and wholegrains, or high in sodium had a much higher mortality rate. Another study found that advice to eat less red meat is not backed by sufficient scientific evidence.
It is not as simple as eliminating red meat to improve both health and the environment. Many factors must be considered in conjunction when making decisions about the food system, as a thinking failure today will lead to a system failure tomorrow.
A recent report published by EpiX in The Journal of Nutrition suggests that the EAT-Lancet proposed diet has no greater impact on mortality reduction than energy consumption changes.
The EAT-Lancet reference diet promotes an increase in plant-based food, and a reduction in red meat and sugar intake. The authors claim this can reduce premature deaths caused by diet-related noncommunicable diseases (NCD) by between 10.9 and 11.6 million per year. However, EpiX has identified that the EAT-Lancet report does not meet standards for transparency and replicability. Nor does it fully account for statistical uncertainty. Once uncertainty is accounted for and calculation errors are fixed, the impact on mortality reduction is less significant. In fact, the impact is no greater than changes in energy consumption that would prevent underweight, overweight and obesity alone.
The aim of the EAT-Lancet report – to determine an optimal global diet from a sustainable food system to improve both human and planetary health – is to be commended. It asks all the right questions; the problem is the assumptions and methods used appear to have fallen short. The report has had a massive uptake in media and social media, in part by a well-managed and orchestrated campaign by the EAT movement. According to Stockholm University, in the first 2 months after the report was released in January 2019, there were 5800 articles in 118 countries with over one million shares on social media. Given the need to make the global food system more sustainable, and the concerns raised about the validity of the recommendations made in the EAT-Lancet report, this is worrisome. It is important to avoid a thinking failure today to avoid a system failure tomorrow.
If there are health benefits from eating less beef and pork, they are small, and not sufficient to tell individuals to change their meat-eating habits. Links are mostly in studies that observe groups of people, and even then, are only detectable in the largest groups.
This raises questions about the longstanding dietary guidelines urging people to eat less red meat. There have been concerns for years that red meat causes heart disease, cancer and other illnesses. However, if this is not backed by good scientific evidence it should not influence dietary guidelines. Red meat plays a key role in the contribution to multiple micro-nutrient requirements such as iron, zinc and vitamin B12. Research from the Global Burden of Disease study found that 11 million deaths and 255 million disability-adjusted life years were attributable to dietary risk factors, however the key risk factors were under-consumption of whole grains and fruits, and meat was found to have very little impact. It may be that high consumption of red meat is not inherently unhealthy, but rather a lack of choice and/or poor choice means a high level of red meat in the diet results in lower consumption of other healthy foods in the diet. In other words, is not red meat itself causing disease, but the lack of other foods as part of a balanced diet.
Therefore, it may not be in individual’s best interests to decrease red meat consumption, instead we should focus on consuming a balanced diet of healthy foods and sufficient nutrients.