A cross-sectional survey of the readiness of consumers to adopt an environmentally sustainable diet

This research study employed a quantitative approach in the form of a cross-sectional, online survey of consumers’ perceived environmental benefit and readiness to adopt sustainable dietary recommendations. We aimed to expand on international research in this field in light of sustainable dietary guidelines recently published in the UK [25].

Inclusion criteria for the study were that participants must be adults currently living in the UK. Children ≥18 years old were not eligible to take part. The study was promoted via the Environment Agency, a non-departmental public body with responsibilities relating to the protection and enhancement of the environment in England. However, participants were not required to be employees of the Environment Agency to take part in the study.

A questionnaire was developed for the purposes of this study, based on a review of existing measures that have been used to assess public perceptions of sustainable dietary behaviours [35, 37, 39, 41]. Participants’ perceived environmental benefit of nine sustainable diet behaviours (avoid excess packaging; buy locally grown produce; consume seasonal fruits and vegetables; limit red and processed meat; prioritise plant proteins e.g. Quorn, beans, nuts, tofu; reduce consumption of air freighted foods; choose sustainable fish; reduce food waste; choose organic produce) was measured using a 5-point Likert scale from ‘very small benefit’ to ‘very large benefit’. The behaviours chosen were based on environmentally sustainable dietary guidelines published by the BDA [25].

Readiness to adopt these behaviours was measured using one question with six response options that corresponded with the stage of change construct of the Transtheoretical Model of behaviour change [51]. The stage of change construct provides a useful cross-sectional measure of an individual’s readiness to adopt a particular behaviour and has previously been used to measure readiness to adopt environment and health-related behaviours [38, 39] However, it is limited in that it does not measure actual behaviour and also does not provide information as to how or why an individual transitions between stages. The response options provided in the survey were: ‘I am not interested in doing this at the moment’ (pre-contemplation), ‘I am thinking about this but I need more information’ (contemplation), ‘I would like to do this but there are things stopping me’ (planning), ‘I have started to do this some of the time’ (action), ‘I am doing this confidently most of the time’ (maintenance), and ‘I am not currently doing this but have done in the past’ (relapse).

To understand the factors that influence participants’ dietary choices, they were asked to select the three most important food-choice motives from a provided list (health, cost, religion, taste, environmental sustainability, availability, animal welfare, and weight loss). Participants were also asked to report their typical weekly frequency of consumption of animal-based (white meat, red meat, processed meat, dairy products, eggs, and fish) and plant-based (beans/lentils, processed meat alternatives, non-dairy milks, and nuts/seeds) sources of protein. The socio-economic information collected was age group, gender, education level, geographic location, and whether participants had children living at home.

The data collection tool was pre-tested via cognitive interviews with five individuals from different demographic groups within the recruitment pool. Cognitive interviewing is a useful method to ensure that participants understand and interpret the questions as intended and the response options are appropriate [52]. This was particularly important as previous research suggests that many people are not familiar with the topic of sustainable diets [40, 53]. Modifications were made to the questionnaire as a result, including addition of the ‘relapse’ stage of change response option and listing specific examples of plant-based proteins in the food frequency questionnaire.

Written permission to recruit employees from the Environment Agency was obtained prior to data collection. An online survey tool, Smart Survey, was used to deliver the questionnaire. A self-recruit sampling method was utilised whereby a link to the online survey was shared via company e-newsletters and employees were invited to participate and to share the link with friends and family. The data collection period ran for a total of 6 weeks from July to August 2019. Ethical approval to conduct the study was granted by the appropriate Ethics Review Committee at Edge Hill University.

Compared to the UK population, the study sample had a higher proportion of females (66% vs. 51%) [55] and those with a higher education level (85% vs. 50%) [56]. As participants were primarily employed adults, there is limited representation from adults ≥65 years old and children ≤18 years old, who in total represent over a third of the UK population [55].

For most of the sustainable diet recommendations studied, at least 50% of participants perceived a high environmental benefit and reported being in the action or maintenance stage of change. Furthermore, over half of participants stated environmental sustainability as an influence on their dietary choices. This indicates that overall, the study participants are aware of the relationship between food and the environment and are engaged with sustainable diet recommendations. Additionally, the proportion of participants in the relapse stage of change was low for all recommendations indicating that if consumers can be influenced to adopt sustainable diet recommendations, behaviour change can be maintained long term. However, it is important to note the potential for social-desirability bias in surveys and that participants’ responses may not reflect their actual purchasing behaviour [57].

The behaviours considered to offer the largest environmental benefit were ‘reduce consumption of air-freighted foods’, ‘reduce food waste’, and ‘buy locally grown produce’. ‘Consume seasonal fruits and vegetables’, ‘limit red and processed meat’, ‘avoid excess packaging’ and ‘choose sustainable fish’ were also perceived to have a high environmental benefit by most participants. Conversely, participants deemed ‘prioritise plant-based proteins’ and ‘choose organic produce’ to have a lower environmental benefit. Studies using LCA to determine GHG emissions [9] and overall environmental impact [24] of foods demonstrate that avoiding air-freighted foods, choosing organic produce and consuming a plant-based diet are the dietary behaviours which have the largest environmental benefit. This highlights that consumers are aware that the food system impacts the environment but may not understand the impact of specific dietary behaviours as their perceptions are not in line with actual environmental benefit, according to these studies.

This finding is not surprising as determining overall environmental impact is complex due to its many facets, for example, organic farming uses fewer resources and has lower direct GHG emissions but agricultural yields are lower resulting in increased indirect GHG emissions due to land-use change and the need to import food to meet demand [58]. Johnson et al. describe the complexities in defining a sustainable diet in terms of health, food security and environmental sustainability and highlight the need for developing metrics and measurement mechanisms for sustainable diets [10]. Food labels (e.g. Fair Trade, Rainforest Alliance, Carbon Footprint) are a useful way to communicate information to consumers who are motivated to make ethical purchases [59] but may be confusing for consumers when there are trade-offs between different aspects of a sustainable diet.

That the recommendations to ‘reduce food waste’ and ‘avoid excessive packaging’ were perceived to have a high environmental benefit is not surprising as there have been recent media campaigns promoting these issues [60‐63]. Additionally, most participants were in the action and maintenance stages of change for these behaviours. However, in terms of environmental impact, the relationship between these two behaviours is complex and may have competing outcomes. For example, packaging plays a key role in preventing food waste by preserving and protecting food in transport and storage [64] and only contributes 3% to the total food-related GHG emissions [9]. Therefore, by purchasing foods with less packaging consumers may be inadvertently increasing food waste elsewhere in the supply chain and increasing the overall environmental footprint of the food system.

On the other hand, there are instances when packaging design leads to increased food waste in the home by encouraging over-purchasing (e.g. multipacks, special offers), being difficult to empty fully or due to conservative sell-by dates [50]. There are also a wide variety of packaged foods including fresh produce, meat and fish, dairy products as well as processed foods such as cereals and confectionary. The concept of ‘excess packaging’ is ambiguous and could potentially lead to confusion amongst consumers or avoidance of nutritious foods such as fruits and vegetables which are often packaged. For this reason, it may be prudent not to include avoiding foods with excessive packaging amongst sustainable dietary guidelines but instead to focus on behaviours such as avoiding highly processed foods, only buying the quantity of food required, using left-overs and recycling packaging where possible.

A larger proportion of participants reported that they have already started to adopt the recommendations to ‘reduce food waste’ and ‘avoid excess packaging’, compared to ‘prioritise plant-based proteins’ and ‘choose organic produce’. This suggests that behaviours which require no nutrition knowledge or significant dietary changes are more readily adopted by consumers. O’Keefe et al. [43] also observed that behaviours are perceived more positively when they fit within an individual’s existing competencies. Redesign of packaging to reduce food waste or use of bio-degradable materials is another effective way to reduce the environmental impact of packaging which does not require decision-making or action from the individual [65]. Promotional campaigns and interventions could then focus on improving consumers’ nutrition knowledge and skills to enable them to adopt behaviours which have a larger overall environmental benefit, rather than on avoiding packaging waste.

The results of this study indicate a high level of awareness of the environmental impact of red and processed meat consumption and three-quarters of participants reported that they have already started to limit these foods. On the other hand, a quarter of participants reported being in the pre-contemplation stage of change for this behaviour indicating that there are some individuals who are resistant to reducing meat consumption. Barriers to reducing meat consumption include a strong attachment to the taste and familiarity of meat [36, 66] and the belief that personally reducing meat consumption will not make a significant difference on a global scale [42]. Those with a strong attachment to meat consumption may deny its negative impacts to reduce their cognitive dissonance [67]. For consumers resistant to reducing meat consumption it may be better to promote replacing conventional red and processed meat products with lower environmental impact alternatives such as white meat and sustainable fish which have been shown to be more readily accepted than plant-based protein sources [40]. As almost two-thirds of participants reported choosing sustainable fish some or most of the time and most participants reported consuming fish at least once per week, sustainable fish may be a culturally acceptable alternative to meat.

Only a small proportion of participants reported that they wanted to ‘limit red and processed meat consumption’ and ‘prioritise plant-based proteins’ but there were barriers preventing them. This was a surprising result as several practical barriers to reducing meat consumption have been identified including lack of choice when eating out and difficulty preparing vegetarian meals [37, 40, 53]. As there has been an increase in meat-free options in UK restaurants and supermarkets in recent years as well as campaigns promoting how to adopt a meat-free diet [68, 69] these barriers may be becoming less relevant for UK consumers. However, the potential health and environmental benefits of reducing meat consumption depends what replaces meat in the diet [8]. For example, 46% of participants reported consuming processed meat alternatives at least once per week (Fig. 1) which are not nutritionally comparable with meat and may be missing key nutrients such as iron, zinc and vitamin B12 [70].

Additionally, over 85% of participants reported that they consume nuts, seeds, beans and lentils at least once per week (Fig. 1) but modelling studies calculating the potential reductions in GHG emissions from healthy, sustainable diets have typically not focused on replacing meat with other plant-based sources of protein specially but on a variety of plant-based foods, including fruits, vegetables and cereals as well [8, 19]. Therefore it is not clear what the environmental benefit would be if meat were replaced by these plant-based sources of protein. Rosi et al. compared reported dietary data for omnivores, vegetarians and vegans and observed that meat-free diets generally had a lower environmental impact in terms of water use, land use and CO₂ emissions but that some vegan participants had an extremely dietary environmental footprint due to only consuming fruits [17]. Therefore, it is important for policy and interventions encouraging sustainable diets to promote consumption of healthy foods which also have a low environmental footprint, rather than solely encouraging consumers to eat less meat.

Despite being perceived as important aspects of a sustainable diet, avoiding air-freighted foods and buying local and seasonal produce appear to be difficult behaviours for consumers to adopt with 30–50% in the contemplation and planning stages of change. Lack of availability of local, seasonal produce may be a significant barrier in the UK as over half of food sold is imported [71]. Knowledge of seasonality of foods is low amongst UK consumers which may be due to supermarkets stocking imported produce all year round [43]. Swedish national dietary guidelines promote traditional foods and a higher proportion of the Swiss population report consuming local and seasonal produce [39, 72]. Conversely, UK consumers are encouraged to eat a Mediterranean-style diet to avoid disease despite many of these foods not being native to the country [73]. The results of the current study therefore suggest a need for exploration of policy to enable motivated consumers to adopt these behaviours, for example promoting local and seasonal produce via dietary guidelines and subsidizing local agriculture.

Government policy also has potential to make organic agriculture more economically viable for farmers [74]. Although choosing organic produce has a significant environmental benefit, it was perceived to have the lowest environmental benefit of all of the recommendations and only a third of participants have started to adopt this behaviour. The higher price and lack of availability in supermarkets have previously been identified as barriers to consumers purchasing organic products [75, 76] therefore, reducing the price may increase willingness to adopt this behaviour amongst consumers who perceive this behaviour to be important. However, a third of participants reported being in the pre-contemplation and contemplation stage of change therefore it is clear that strategies to raise awareness of the environmental impact of conventional farming methods and the benefits of organic farming are also needed.

Younger participants and those with a higher education level perceived the recommendations to ‘limit red and processed meat consumption’ and ‘prioritise plant-based proteins’ to have a higher environmental benefit, compared to older participants (Table 3), although this did not correspond to being more ready to adopt these behaviours (Table 5). The interest in plant-based diets amongst younger consumers may be explained by the emergence of nutrition and dietary trends within urban areas and celebrity endorsement of meat-free diets [77, 78]. Higher meat consumption has been associated with lower education level and social class [79, 80] and it has been observed that younger consumers associate healthy eating with moral worth and social status [81]. It may also be that adopting a plant-based diet is now perceived as morally superior due to the negative impact of meat consumption on individual heath and the environment [77].

Females associated a higher environmental benefit with all sustainable diet recommendations, although this finding was only significant for ‘consume seasonal fruits and vegetables’, ‘reduce food waste’, ‘choose organic produce’ and ‘choose sustainable fish’. Women are typically more involved with food purchasing and preparation which could lead to them being more aware of food-related issues [36, 82]. Ethical consumption habits are generally considered to be more feminine which could lead to males disregarding these behaviours [83]. Furthermore, female were more likely to report adopting behaviours relating to reducing meat consumption which reflects UK National Diet and Nutrition Survey (NDNS) data [84]. This is not surprising due to the connotations of meat and masculinity [85, 86] therefore overcoming these gender stereotypes is necessary to influence male consumers to adopt sustainable diet recommendations.

Older participants were more concerned about the impact of food waste, which has previously been attributed due to generational rather than age-related differences in food-habits and values [38]. Studies of food waste highlight that the main reasons for generating food waste amongst younger consumers are concerns over freshness [87] improper storage and excessive purchasing due to more frequent shopping and retail marketing strategies [88, 89]. Older consumers may also have greater skill and knowledge to plan meals and use leftover food [88, 90]. Therefore, both raising awareness of the impact of food waste amongst younger consumers as well as knowledge and skills for reducing food waste is important. On the other hand, those ≥35 years old were twice as likely to be in the pre-contemplation and contemplation stages of change compared to action and maintenance for ‘choose organic produce’ and ‘choose sustainable fish’, indicating that younger generations are more engaged with these behaviours. Purchasing organic food and sustainable fish have been associated with presentation as a ‘green consumer’ which is more prevalent amongst younger consumers, particularly those with a higher education level which is reflected in our findings [91, 92]. This is an interesting topic which could be explored further as there may the potential to develop ‘green consumer’ role models which could also appeal to older consumers.

This study employed a self-recruit sampling method which has the limitation that those with an interest in the topic may be more inclined to take part [93]. Additionally, the study recruited participants primarily from the Environment Agency employees who may be more aware of sustainability issues than the general public due to the nature of their employment. Our sample included a higher proportion of females and university educated individuals which is a common limitation of studies in this field. The sample was also concentrated in several urban regions of England, therefore is not representative of consumers living in rural areas or in other parts of the UK.

Additionally, aspects of the study are based on participant’s reported dietary intake, food choice motives and behaviours which may not reflect their actual actions. The methods employed in this study, particularly the stage of change construct, are suitable for meeting the objective of assessing consumers’ readiness to adopt sustainable dietary recommendations but may not represent actual purchasing behaviour. Previous studies have highlighted that self-reported dietary data can be used to inform public guidance and policy [94], however adjustment is required to account for under-reporting [95]. It would therefore be beneficial for future studies to analyse actual consumer food purchases and use alternative methods of measuring dietary intake such as 24-h recall or food diary assessments.