Jennie I. Macdiarmid

Sustainable diets for the future: can we contribute to reducing greenhouse gas emissions by eating a healthy diet?

BACKGROUND Food systems account for 18-20% of UK annual greenhouse gas emissions (GHGEs). Recommendations for improving food choices to reduce GHGEs must be balanced against dietary requirements for health. OBJECTIVE We assessed whether a reduction in GHGEs can be achieved while meeting dietary requirements for health. DESIGN A database was created that linked nutrient composition and GHGE data for 82 food groups. Linear programming was used iteratively to produce a diet that met the dietary requirements of an adult woman (19-50 y old) while minimizing GHGEs. Acceptability constraints were added to the model to include foods commonly consumed in the United Kingdom in sensible quantities. A sample menu was created to ensure that the quantities and types of food generated from the model could be combined into a realistic 7-d diet. Reductions in GHGEs of the diets were set against 1990 emission values. RESULTS The first model, without any acceptability constraints, produced a 90% reduction in GHGEs but included only 7 food items, all in unrealistic quantities. The addition of acceptability constraints gave a more realistic diet with 52 foods but reduced GHGEs by a lesser amount of 36%. This diet included meat products but in smaller amounts than in the current diet. The retail cost of the diet was comparable to the average UK expenditure on food. CONCLUSION A sustainable diet that meets dietary requirements for health with lower GHGEs can be achieved without eliminating meat or dairy products or increasing the cost to the consumer.

Is a healthy diet an environmentally sustainable diet

The concept of a healthy and environmentally sustainable diet is not new, but with increasing concern about future global food security and climate change there is a renewed interest in this topic. Dietary intakes in UK accounts for approximately 20-30% of total annual greenhouse gas emissions (GHGE), with the greatest contributions coming from high intakes of meat and dairy products. Dietary proposals to help mitigate climate change (i.e. reduce GHGE) have focused on reducing consumption of meat and dairy products, but this must be considered in the context of the whole diet, alongside any possible nutritional consequences for health. Bringing together health and environmental impact of the diet raises the question of whether a healthy diet can also be an environmentally sustainable diet. While recent research showed that it is possible to achieve a realistic diet that meets dietary requirement for health and has lower GHGE, it cannot be assumed that a healthy diet will always have lower GHGE. With different combinations of food it is possible to consume a diet that meets dietary requirements for health, but has high GHGE. It is important to understand what constitutes a sustainable diet, but this then needs to be communicated effectively to try and change well-established dietary intakes of the population. Studies show that understanding of sustainable diets is poor and there are many misconceptions (e.g. the overestimation of the protein requirements for a healthy diet), which could contribute to the barriers towards changing dietary intakes.

The influence of the food environment on overweight and obesity in young children: a systematic review

Background and objective The increasing prevalence of childhood obesity has led to interest in its prevention, particularly through school-based and family-based interventions in the early years. Most evidence reviews, to date, have focused on individual behaviour change rather than the ‘obesogenic environment’. Objective This paper reviews the evidence on the influence of the food environment on overweight and obesity in children up to 8 years. Data sources Electronic databases (including MEDLINE, EMBASE, Cochrane Controlled Trials Register (CCTR), DARE, CINAHL and Psycho-Info) and reference lists of original studies and reviews were searched for all papers published up to 31 August 2011. Study selection Study designs included were either population-based intervention studies or a longitudinal study. Studies were included if the majority of the children studied were under 9 years, if they related to diet and if they focused on prevention rather than treatment in clinical settings. Data extraction Data included in the tables were characteristics of participants, aim, and key outcome results. Quality assessment of the selected studies was carried out to identify potential bias and an evidence ranking exercise carried out to prioritise areas for future public health interventions. Data synthesis Thirty-five studies (twenty-five intervention studies and ten longitudinal studies) were selected for the review. There was moderately strong evidence to support interventions on food promotion, large portion sizes and sugar-sweetened soft drinks. Conclusions Reducing food promotion to young children, increasing the availability of smaller portions and providing alternatives to sugar-sweetened soft drinks should be considered in obesity prevention programmes aimed at younger children. These environment-level interventions would support individual and family-level behaviour change.

Eating like there's no tomorrow: Public awareness of the environmental impact of food and reluctance to eat less meat as part of a sustainable diet

Reducing meat consumption is central to many of the scientific debates on healthy, sustainable diets because of the high environmental impact of meat production. Missing from these debates are the public perspectives about eating less meat and consideration of cultural and social values associated with meat. The aim of this study was to explore public awareness of the environmental impact of food and their willingness to reduce meat consumption. Twelve focus groups and four individual interviews were conducted with adults from a range of socio-economic groups living in both rural and urban settings in Scotland. Public understanding of the link between food, environment and climate change was explored, with a focus on meat and attitudes towards reducing meat consumption. Data were transcribed and analysed thematically. Three dominant themes emerged: a lack of awareness of the association between meat consumption and climate change, perceptions of personal meat consumption playing a minimal role in the global context of climate change, and resistance to the idea of reducing personal meat consumption. People associated eating meat with pleasure, and described social, personal and cultural values around eating meat. Some people felt they did not need to eat less meat because they had already reduced their consumption or that they only ate small quantities. Scepticism of scientific evidence linking meat and climate change was common. Changing non-food related behaviours was viewed as more acceptable and a greater priority for climate change mitigation. The study highlights the role meat plays in the diet for many people, beyond nutritional needs. If healthy, sustainable dietary habits are to be achieved, cultural, social and personal values around eating meat must be integrated into the development of future dietary recommendations.

Priority research questions for the UK food system

The rise of food security up international political, societal and academic agendas has led to increasing interest in novel means of improving primary food production and reducing waste. There are however, also many ‘post-farm gate’ activities that are critical to food security, including processing, packaging, distributing, retailing, cooking and consuming. These activities all affect a range of important food security elements, notably availability, affordability and other aspects of access, nutrition and safety. Addressing the challenge of universal food security, in the context of a number of other policy goals (e.g. social, economic and environmental sustainability), is of keen interest to a range of UK stakeholders but requires an up-to-date evidence base and continuous innovation. An exercise was therefore conducted, under the auspices of the UK Global Food Security Programme, to identify priority research questions with a focus on the UK food system (though the outcomes may be broadly applicable to other developed nations). Emphasis was placed on incorporating a wide range of perspectives (‘world views’) from different stakeholder groups: policy, private sector, non-governmental organisations, advocacy groups and academia. A total of 456 individuals submitted 820 questions from which 100 were selected by a process of online voting and a three-stage workshop voting exercise. These 100 final questions were sorted into 10 themes and the ‘top’ question for each theme identified by a further voting exercise. This step also allowed four different stakeholder groups to select the top 7–8 questions from their perspectives. Results of these voting exercises are presented. It is clear from the wide range of questions prioritised in this exercise that the different stakeholder groups identified specific research needs on a range of post-farm gate activities and food security outcomes. Evidence needs related to food affordability, nutrition and food safety (all key elements of food security) featured highly in the exercise. While there were some questions relating to climate impacts on production, other important topics for food security (e.g. trade, transport, preference and cultural needs) were not viewed as strongly by the participants.

Achieving dietary recommendations and reducing greenhouse gas emissions: modelling diets to minimise the change from current intakes

BackgroundAverage population dietary intakes do not reflect the wide diversity of dietary patterns across the population. It is recognised that most people in the UK do not meet dietary recommendations and have diets with a high environmental impact, but changing dietary habits has proved very difficult. The purpose of this study was to investigate the diversity in dietary changes needed to achieve a healthy diet and a healthy diet with lower greenhouse gas emissions (GHGE) (referred to as a sustainable diet) by taking into account each individual’s current diet and then minimising the changes they need to make.MethodsLinear programming was used to construct two new diets for each adult in the UK National Diet and Nutrition Survey (n = 1491) by minimising the changes to their current intake. Stepwise changes were applied until (i) dietary recommendations were achieved and (ii) dietary recommendations and a GHGE target were met. First, gradual changes (≤50 %) were made to the amount of any foods currently eaten. Second, new foods were added to the diet. Third, greater reductions (≤75 %) were made to the amount of any food currently eaten and finally, foods were removed from the diet.ResultsOne person out of 1491 in the sample met all the dietary requirements based on their reported dietary intake. Only 7.5 and 4.6 % of people achieved a healthy diet and a sustainable diet, respectively, by changing the amount of any food they currently ate by up to 50 %. The majority required changes to the amount of each food eaten plus the addition of new foods. Fewer than 5 % had to remove foods they ate to meet recommendations. Sodium proved the most difficult nutrient recommendation to meet. The healthy diets and sustainable diets produced a 15 and 27 % reduction in greenhouse gas emissions respectively.ConclusionsSince healthy diets alone do not produce substantial reductions in greenhouse gas emissions, dietary guidelines need to include recommendations for environmental sustainability. Minimising the shift from current dietary intakes is likely to make dietary change more realistic and achievable.

Greenhouse gas emissions from agricultural food production to supply Indian diets : Implications for climate change mitigation

Highlights • Highest GHG emissions from food production are from rice and ruminant products.• Highest GHG emissions from consumption are from rice and livestock products.• Consumption choice can either increase or decrease total GHG emissions.

The environmental impact of nutrition transition in three case study countries

This paper explores the environmental impacts of dietary changes consistent with the nutrition transition common in countries going through economic development, inferred from commodity supply data from FAOSTAT. Supply data for 1961 and 2011 from three case study countries which have undergone significant economic transition in recent decades (Brazil, China and India) were compared on a per-capita basis to avoid confounding issues of population growth. Brazil showed marked increases in beef and poultry meat supply (kcal) while in China poultry and pig meat showed marked increases, particularly for pig meat. Per-capita supply of fruit in Brazil and vegetables in China were higher than in Europe by 2011. Supply of vegetable oil increased in all three countries and this was the majority commodity traded, hence much of its impact would have been felt in country of origin. The increase in beef production in Brazil, attributed to changing diet (2001–2011), had the greatest impact on increased water use, although the increase in supply of pig meat in China and cereals in China and India (attributable to changing diets) also made major contributions. The increase in cereal supply in China and India had a major impact on phosphorus and nitrogen cycles, with beef having a major impact on greenhouse gas emissions (GHGs). The increase in vegetable oils had a major impact through increasing land use. These findings highlight differential environmental impacts of the nutrition transition in different countries and emphasise the need to measure environmental impacts beyond those on GHGs.

Seasonality and dietary requirements: will eating seasonal food contribute to health and environmental sustainability?

Eating more seasonal food is one proposal for moving towards more sustainable consumption patterns, based on the assumption that it could reduce the environmental impact of the diet. The aim of the present paper is to consider the implications of eating seasonal food on the different elements of sustainability (i.e. health, economics, society), not just the environment. Seasonality can be defined as either globally seasonal (i.e. produced in the natural production season but consumed anywhere in the world) or locally seasonal (i.e. produced in the natural production season and consumed within the same climatic zone). The environmental, health, economic and societal impact varies by the definition used. Global seasonality has the nutritional benefit of providing a more varied and consistent supply of fresh produce year round, but this increases demand for foods that in turn can have a high environmental cost in the country of production (e.g. water stress, land use change with loss of biodiversity). Greenhouse gas emissions of globally seasonal food are not necessarily higher than food produced locally as it depends more on the production system used than transportation. Eating more seasonal food, however, is only one element of a sustainable diet and should not overshadow some of the potentially more difficult dietary behaviours to change that could have greater environmental and health benefits (e.g. reducing overconsumption or meat consumption). For future guidelines for sustainable diets to be realistic they will need to take into account modern lifestyles, cultural and social expectations in the current food environment.

Global cropland and greenhouse gas impacts of UK food supply are increasingly located overseas

Producing sufficient, healthy food for a growing world population amid a changing climate is a major challenge for the twenty-first century. Agricultural trade could help alleviate this challenge by using comparative productivity advantages between countries. However, agricultural trade has implications for national food security and could displace environmental impacts from developed to developing countries. This study illustrates the global effects resulting from the agricultural trade of a single country, by analysing the global cropland and greenhouse gas impacts of the UKs food and feed supply. The global cropland footprint associated with the UK food and feed supply increased by 2022 kha (+23%) from 1986 to 2009. Greenhouse gas emissions (GHGE) associated with fertilizer and manure application, and rice cultivation remained relatively constant at 7.9 Mt CO2e between 1987 and 2008. Including GHGE from land-use change, however, leads to an increase from 19.1 in 1987 to 21.9 Mt CO2e in 2008. The UK is currently importing over 50% of its food and feed, whereas 70% and 64% of the associated cropland and GHGE impacts, respectively, are located abroad. These results imply that the UK is increasingly reliant on external resources and that the environmental impact of its food supply is increasingly displaced overseas.