7 minute read
GLO BAL NUTRITION
Dr Andrew Fletcher, Professor Warren McNabb and Dr Nick Smith
Sustainable Nutrition Initiative – Feed our Future
Authors: Dr Nick Smith, Dr Andrew Fletcher, Olivia Finer & Professor Warren McNabb, Sustainable Nutrition Initiative, Riddet Institute
For the global food system to be considered sustainable it must deliver enough nutrients to meet the needs of the global population. Researchers at the Riddet Institute have formed the Sustainable Nutrition Initiative (SNI), aiming to analyse how food production meets the nutritional needs of the world.
Goal: global nutrition
Global nutrition means supplying the calories, macro-nutrients (fat, carbohydrates and protein), micro-nutrients and trace elements to individuals, regardless of their place on the planet. To achieve global health, we need global nutrition. SNI research will help to create a better understanding of the world’s food system and identify opportunities for improvement, to sustainably feed everyone with the nutrients required. A sustainable food system is “a food system that delivers food security and nutrition for all, in such a way that the economic, social and environmental bases to generate food security and nutrition for future generations are not compromised. Our food system should be profitable throughout (economic sustainability), have broad-based benefits for society (social sustainability); and have a positive or neutral impact on the natural environment (environmental sustainability)” 1 . While it is essential to examine the environmental and socioeconomic
The Delta Model
consequences of the global food system, ensuring adequate nutrition for future generations should be a priority. SNI has developed a modelling approach to test various scenarios for globally sustainable future food systems: the DELTA Model. This model is unique. It explores the ability of different food production scenarios to adequately feed the global population. It does not try to provide the answer to the perfect sustainable diet for individuals, since what might work for one individual does not necessarily work on a global level. SNI developed the DELTA Model to generate informed discussion around the possibilities for how the world can feed the world. And for the world to feed the world, nutrient-rich foods are required.
Sample output of the DELTA Model comparing the 2018 global food system (left-hand bars) with the same system applied to the 2030 poulation (right-hand bars). The black horizontal lines show the RDI. Although sufficient macronutrients are supplied, there are deficiencies in fibre, calcium, iron, potassium, zinc and Vitamin E in the 2030 scenario. This emphasises the need for research in these areas to ensure adequate nutrition for future generations
The food system must be built from nutrient rich and bioavailable foods
Diets cannot work on a global scale if there are insufficient nutrient-rich foods. In order to produce enough food to meet global requirements within global resource constraints, it is important to start with foods rich in bioavailable nutrients. Moreover, it is not enough to compare nutrient composition directly against requirements; the comparison must also take the bioavailability of individual nutrients in foods into account. Bioavailability refers to the proportion of a consumed nutrient that is absorbed into the bloodstream and used for normal bodily functions. For example, only 1.4% of the iron in spinach can be taken into the body, while 20% of iron from red meat can be absorbed. If bioavailability is accounted for, 1.04kg of spinach needs to be consumed to obtain the same amount of iron as you can get from 100g of beef (our team discussed this in a recent article in North and South Magazine). 3
For most food production system scenarios, a balanced food system with nutrient-rich plant and animal foods is important. Equally as important to address are micro-nutrients and trace elements: the vitamins and minerals that are vital for human function. It is often not the macro-nutrients that limit the provision of adequate nutrition, rather, it is the micro-nutrients and trace elements such as iron, zinc, calcium, vitamin B12 and vitamin C. The richest and best-absorbed sources of calcium are milk products, which are also rich in other nutrients such as high-quality protein and vitamin B12. On the other hand, the best sources of vitamin C and fibre are plants. The most common cause for concern with global diets is the need for increased protein supply, both now and in the future. Proteins consumed by the body supply essential amino acids - the 9 amino acids that cannot be synthesised by the human body. It is important to consider bioavailable, essential amino acid supply and not simply protein when assessing a global sustainable diet. These amino acids are required to manufacture proteins needed for bodily functions, such as building muscle, transporting nutrients and fighting infection. Essential amino acid deficiencies can result in a range of health issues including decreased immunity, digestive problems, lower mental alertness or slowed growth in children. Long term consequences then have impacts both at the individual level and on national economic development and human capital.
How does the Delta Model work?
The Delta Model calculates the bioavailable nutrients supplied in a global food production scenario. This encompasses food production, processing, waste and other uses (e.g. animal fats in soap or sugar cane in biofuels). The model output displays whether a food production scenario delivers adequate nutrition to everyone on the planet, or where it falls short if not. The model assumes that nutrition should come first in assessing future food production scenarios, and will then move to consider the other aspects of sustainability, examining the associated environmental and socioeconomic consequences in later versions of the model. The model draws on food system and nutritional data from the FAO, USDA and the EFSA3. Other models and recommendations of sustainable diets largely make the over-simplification that all foods are equal in bioavailability. The DELTA Model is an improvement on such models, because it adjusts for bioavailability when comparing nutrient supply against requirements. Many other models and recommendations for sustainable diets compare nutrient composition against a generic adult recommended daily intake (RDI). However, this is inaccurate because RDIs vary depending on age, gender and a multitude of other factors. Since the DELTA Model takes a global view of the world feeding the world, the daily requirement per person per day is a weighted average based on the demographics of the global population. The DELTA Model considers the fact that protein quality is not equal in different foods. Foods differ in their essential amino acid composition, and the bioavailability of these amino acids is affected by a range of food factors. The Digestible Indispensable Amino Acid Score (DIAAS) is a method to measure protein quality 4 . A score of 1 or greater is considered a complete source of protein, while a score of less than 1 indicates the food is limiting in one or more essential amino acid. For example, the DIAAS score for wheat is 0.45, for oats 0.67, for soy protein isolate 0.84 and for cow’s milk 1.16. A key observation from the model is that it is not feasible to meet global nutrient requirements with only plant-based sources of nutrition, even with active sourcing of a wide variety of foods, and possibly supplementation and fortification, which may not be a practical or affordable solution on a global scale. The options available to feed the world are not the same as options available to feed individuals, particularly in more affluent parts of the world where people have a lot more choice in their foods and diets. This does not mean the answer to the global food system is an abundance of animal foods. The current food system is plant dominant: 85% of all biomass that leaves the world’s farms is plant-based. The key is that a food system must be optimised with nutrient-rich foods to ensure global nutrient requirements are met. This means plant-food based and animal food optimised. Once possible scenarios of how the world can be nourished are established, the practicality of the food system and improvements required to deliver optimal outcomes must be considered. A solution that can nourish the average global citizen may not necessarily be a viable solution from a holistic view. Wider socioeconomic and environmental factors must be evaluated, such as land and its use, greenhouse gas emissions, water availability and quality, social and economic viability, and so on. If the other consequences of a scenario are not acceptable, then the performance of the environmental or socioeconomic outcomes need to be the focus for improvement. However, the DELTA Model puts nutrition first when assessing sustainable food production systems. Any food production systems that cannot adequately contribute to nourishing the world will be an inadequate use of the world’s scarce and valuable resources.
The Sustainable Nutrition Initiative team includes food scientists, nutrition scientists and mathematical modellers. Drs Nick Smith and Andrew Fletcher are currently working on improvements to the DELTA Model including land use, environmental footprinting, and examining New Zealand’s role in the global food system. SNI is led by Professor Warren McNabb. In addition to the DELTA Model, SNI also produces scientific articles on food system sustainability and provides commentary on food system sustainability research. Website: https://sustainablenutritioninitiative.com/ www.riddet.ac.nz Contact: Professor Warren McNabb Email: W.McNabb@massey.ac.nz
References/Footnotes:
1. http://www.fao.org/3/ca2079en/CA2079EN.pdf 2. https://anemiacentral.com/spinach-for-iron/ 3. “In Defence of Meat and Dairy”, North & South Magazine, December 2019 Issue 4. FAO: United Nations Food and Agriculture Organisation; USDA: United States Department of Agriculture; EFSA: European Food Safety Authority 5. DIAAS https://www.riddet.ac.nz/wp-content/uploads/2019/04/Impact -Case-01-Measuring-the-protein-in-your-diet.pdf
