Viewpoint pubs.acs.org/est
Cite This: Environ. Sci. Technol. XXXX, XXX, XXX−XXX
Three Main Ingredients for Sustainable Diet Research Bradley Ridoutt*,†,‡ and Jing Huang§,⊥
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Commonwealth Scientific and Industrial Research Organisation (CSIRO), Agriculture and Food, Clayton South, Victoria 3169, Australia ‡ University of the Free State, Department of Agricultural Economics, Bloemfontein 9300, South Africa § College of Life Science and Engineering, Southwest University of Science and Technology (SWUST), Mianyang 621010, China ⊥ Institute of Environmental Sciences (CML), Leiden University, 2333 CC Leiden, The Netherlands and ethical views which can overwhelm and even undermine the role of science. There is an urgent need for more context-specific research on the subject of sustainable healthy diets to meet the demands of authorities responsible for public health nutrition policy and education, healthcare professionals, and concerned members of society. There is also an urgent need for guidance in the interpretation of the evidence that already exists. In this Viewpoint, we identify three essential elements, or main ingredients, that can support progress in this important research field.
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FOCUS ON FOODS NOT COMMODITIES Rarely do people eat agricultural commodities directly. They eat foods that have undergone varying degrees of processing: some minimally processed, others ultraprocessed. The major public health nutrition challenges associated with overweight, obesity, and inadequate intake of micronutrients are mostly to do with inadequate consumption of nutrient-rich core foods and overconsumption of energy-dense nutrient-poor (EDNP) noncore foods, sometimes referred to as discretionary foods. In some cases, more than 40% of dietary energy is coming from these foods (Figure 1). And this is not just in western
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iets should be healthy. They should also be sustainable. Unfortunately, poor dietary habits are a risk factor linked to one in five deaths globally.1 In addition, the food system that supports these dietary habits is a leading source of environmental impact, particularly through land and water use, and also emissions to soil, air, and water. For some time now, the subject of sustainable diets has been growing in momentum. Already, some countries are formulating national dietary guidelines not only with a view to improving population health, but also the health of the planet. The recent EAT-Lancet Commission report on the subject is expected to further stimulate interest and action.2 However, defining a healthy diet with lower environmental impact is not straightforward. Food products are many and food production systems are widely heterogeneous, environmental challenges vary between regions, local communities have different food cultures, and public health nutrition challenges vary between countries and between population subgroups within countries. Policies and actions directed toward improving the nutritional quality and sustainability of diets should be informed by science-based evidence. However, despite the growth in literature on the topic, the evidence base is fragmentary, of variable quality, and offers few generalizable conclusions.3 To further complicate matters, the subject can be deeply emotive, colored by strongly held individual political © XXXX American Chemical Society
Figure 1. Proportion of dietary energy from noncore (discretionary) foods in Australia. Data source: Australian Bureau of Statistics. Received: February 13, 2019
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DOI: 10.1021/acs.est.9b00935 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
Viewpoint
Environmental Science & Technology
As national dietary guidelines undergo their periodic review, the authorities responsible will need to respond to the increasing demand for sustainability considerations. The three main ingredients presented in this Viewpoint can guide the development of the robust evidence base that will be needed.
countries. The increased consumption of highly refined carbohydrates and foods low in fiber and containing added sugar and salt, has led to widespread increases in the incidence of overweight and obesity across low and middle-income countries, and even as far as rural areas of East Asia, South Asia, and Sub-Saharan Africa.4 The point is that the same agricultural commodities can by transformed into foods for consumption that vary in healthiness. Raw milk can be processed into reduced-fat milk or yogurt (healthy core foods) or ice-cream and other dairy desserts (noncore foods which should only be consumed occasionally and in small amounts). Fruit can be eaten whole, or processed into juice whereby the majority of fiber is removed. Cereals can be the basis of wholegrain foods or highly refined white bread, cakes, biscuits, pastries, doughnuts, etc. Unfortunately, much of the sustainable diets research is based on agricultural commodity production and is disconnected from the actual food choices that are needed to improve diet quality.
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AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. ORCID
Bradley Ridoutt: 0000-0001-7352-0427 Notes
The authors declare the following competing financial interest(s): B.G.R has previously undertaken food systems research related to environmental issues for a variety of private sector organizations and Australian government agencies, including Meat and Livestock Australia.
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RESPECT NUTRIENT REFERENCE VALUES PUBLISHED BY INDEPENDENT AUTHORITIES Food-based dietary guidelines exist in more than 100 countries. They are developed taking into account the local food supply and culinary culture, and are designed to achieve adequate intake of vitamins, minerals, and macronutrients at the population level. The nutrient reference values used are established by independent authorities that periodically review the available scientific evidence and take into account individual variations in absorption and metabolism. For example, in the U.S., this is the task of the Health and Medicine Division of the National Academies. What is alarming is the frequency with which sustainable diet research is undertaken using dietary scenarios which differ from national dietary guidelines without the precaution of evaluating nutrient adequacy. In other cases, nutrient reference values are lowered to accommodate study objectives. Contributing clinical evidence that can be taken into consideration when nutrient reference values are reviewed is an important undertaking. However, this is a separate task from defining a sustainable diet. For the purpose of sustainable diet research, nutrient reference values established by independent authorities should be respected.
ACKNOWLEDGMENTS J.H. is supported by a grant from China’s National Key Research and Development Program to undertake research on sustainable food production (No. 2016YFD0300210). B.G.R has previously undertaken food systems research related to environmental issues for a variety of private sector organizations and Australian government agencies, including Meat and Livestock Australia.
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REFERENCES
(1) Gakidou, E.; et al. Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks, 1990−2016: a systematic analysis for the Global Burden of Disease Study 2016. Lancet 2017, 390, 1345−1422. (2) Willett, W.; et al. Food in the Anthropocene: the EAT-Lancet Commission on healthy diets from sustainable food systems. Lancet 2019, 393, 447−492. (3) Ridoutt, B. G.; Hendrie, G. A.; Noakes, M. Dietary strategies to reduce environmental impact: A critical review of the evidence base. Adv. Nutr. 2017, 8, 933−946. (4) Jaacks, L. M.; Slining, M. M.; Popkin, B. M. Recent underweight and overweight trends by rural−urban residence among women in low- and middle-income countries. J. Nutr. 2015, 145, 352−357. (5) Ridoutt, B. G.; Huang, J. Environmental relevance − the key to understanding water footprints. Proc. Natl. Acad. Sci. U. S. A. 2012, 109, E1424.
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USE ENVIRONMENTAL INDICATORS THAT MAKE SENSE IN A LIFE CYCLE CONTEXT Life cycle assessment (LCA) is an important discipline for sustainable diets research. This is because food systems are complex, with many types of resource use and emissions that occur in many different places. Unfortunately, the environmental metrics that are often chosen for use in sustainable diet studies do not provide reliable evidence when used in a life cycle context.3 For example, total water use. Numerous research articles and even an international standard (ISO 14046:2014) have emphasized the need to consider regional differences in water scarcity. It is well-known that environmental assessments from a life cycle perspective that fail to take into account water scarcity can arrive at entirely the wrong conclusions, as described for crop production in China.5 The same problems emerge with land use. Different land resources have different agricultural production potential, different biodiversity value, etc. As for nitrogen and phosphorus, surely the concern is emissions not use. B
DOI: 10.1021/acs.est.9b00935 Environ. Sci. Technol. XXXX, XXX, XXX−XXX
