The philosophy of the Sustainable Nutrition Initiative (SNI) is to help create a better understanding of our food systems and identify opportunities for optimisation and improvement. This is to ensure that in the future we can sustainably feed the global population. SNI has developed a modelling approach to test any range of possible scenarios that could contribute to globally sustainable future food systems; The DELTA Model. This Model is unique because it explores the ability of different food production scenarios to provide the bioavailable nutrients needed to adequately feed the global population. It does not try to provide the answer to the perfect sustainable diet for individuals. Rather, it uses scenario testing to generate informed discussion about possible future food production systems.
The options available to feed the world are not the same as the options available to feed individuals. Individuals, particularly those that can afford to, have a lot more choice in their foods and diets, including fortified foods and supplements to ensure their nutrient requirements are met. However, the world’s poorest already spend a large percentage of their income on food and have limited ability to spend more on food. This problem intensifies if food becomes more expensive as a result of changes in global production. Therefore, any recommended changes to food production systems need to ensure that the food they produce is affordable on a global basis. Furthermore, certain diets are not practical at a global level as they would require significant and costly changes to food production and distribution systems. The focus of improving and optimising food systems should be on how the world’s total food production can feed the world’s total population, not dictating an individual diet.
Some individuals have flexibility in their choice of diet
The primary focus of any sustainable food system is to meet nutrient requirements of the population. Looking on an individual scale, all nutrient requirements including macro-nutrients, essential amino acids, and micro-nutrients and trace elements must be satisfied to ensure health and wellbeing. An individual with the wealth and means is likely to be able to meet such requirements on any given diet. Those that can afford it can select a range of nutritious foods and take supplementation and fortified foods where required.
One example is a vegan diet. By omitting meat and dairy, it can be harder to reach the required intake of bioavailable essential amino acids and micro-nutrients, such as such as calcium, iron, zinc and vitamin B12. This is because such nutrients are best sourced from animal-based food groups. However, it is possible to meet nutrition requirements through plant-based foods only with the addition of processed fortified foods and/or supplements to provide the essential micro-nutrients that plant-based foods are often poor sources of. An individual with the wealth and means can consume a variety of nutrient-rich plant-based foods to meet the majority of their nutritional requirements. For example, nuts are high in protein, and pulses contain vitamins and minerals such as folate, iron and zinc. Individuals must also ensure they are consuming a variety of protein sources to ensure they meet their requirements for all essential amino acids, particularly lysine which is often the most limiting amino acid. Most plant-based foods are not complete sources of all essential amino acids. However, if a variety of sources are consumed as part of a meal, requirements can be satisfied.
Not all diets are affordable by everyone
However, some of these choices are only affordable and accessible to wealthier individuals in some parts of the world. The world’s poor spend a much higher proportion of their income on food. The lowest expenditure quintile of the population in Ghana for example, spend over 70% of their household budget on food. Within the US, the lowest income quintile spends approximately 35% of their income on food, while the highest quintile spends only 8% (figure 1). Those that are wealthy have greater flexibility to change their expenditure on food and supplementation as required to fit their chosen diet and lifestyle. Unfortunately, not everyone has this opportunity.
Changes in global food production can make food even more expensive. For example, a significant increase in production of pulses and nuts to meet a global vegan diet would require increases in prices to incentivise suppliers to move away from production of other profitable crops or livestock. Supply of some products may not be able to react quick enough to meet demand, for example tree nuts can take 3 to 10 years before the trees start producing nuts. This will further drive up prices.
However, as prices increase, food unaffordability on a global scale will increase. Research that reviewed 1600 US-based studies on food price elasticity found the value of mean price elasticity to be about -0.60 for cereals and vegetables. This means if the price of cereals and vegetables were to increase by 25%, demand would decrease by approximately 15% globally. These drops in demand would be greater for lower-income households compared to higher-income households, as food is more likely to become unaffordable as prices increase. As a result, the poor, who already struggle to consume adequate nutrients, will be able to afford even less. Even more modest increases in price will render many households unable to afford the food they need.
Changes in diets on a global scale have impracticalities in terms of cost and time required to make the change
Making changes to diets on a global scale may require significant changes to the global food systems in terms of the size of the change and time required, and therefore may not be practical. For example, the world adopting a solely vegan diet as mentioned above, would require land and resources to be converted from livestock to crop production. Production of nutrient-rich plant-based foods such as nuts and legumes would need to be significantly increased. It is one thing to change attitudes, but physical changes to the food systems can be much more difficult. Physical resources would need to be re-allocated, bearing a large cost and requiring a significant amount of time. Cutting animal production would also affect the one billion people who rely on livestock for food and livelihoods.
The focus of improving and optimising the food system should be on the world feeding the world, not dictating an individual diet
Freedom of choice about food can work at an individual level where people have the wealth and means to select the food they want. However, there is no ‘one size fits all’ when it comes to what the world should eat. Diets will vary based on economic and social factors such as income, culture, religion, geographical location and so forth. Moving the entire world to a given diet can result in many being unable to afford nutrition, or costly and time-consuming changes to food systems. Instead, the focus of improving and optimising the food system should be on how the world can feed the world. The scenario-based approach that the DELTA Model allows users to analyse different possibilities of how the world’s total food production can feed the world’s total population. It does not dictate an individual diet, rather it focuses on improvement and optimisation of future food systems.
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