Dr Joanna Trewern

Doctoral Practitioner in Sustainability
MSc Biodiversity, Conservation and Management; BA History and Spanish

Academic and research departments

Centre for Environment and Sustainability.


My research project


Joanna Trewern, Jonathan Chenoweth, Ian Christie, Emma Keller, Sarah Halevy (2021)Are UK retailers well placed to deliver ‘less and better’ meat and dairy to consumers?, In: Sustainable Production and Consumption28pp. 154-163 Elsevier B.V

Retailers can play an important role in facilitating a transition to sustainable diets in the UK. They have been implementing strategies aimed at helping customers make healthier choices and are now considering how to broaden this to include sustainability, which is a live discussion in the UK retail sector. Focusing on ‘less and better’ meat and dairy as a core component of sustainable diets, this study investigates retailer perceptions of sustainable diets and their strategies and challenges to provide and promote customer purchasing of ‘less and better’ meat and dairy. Results from a series of semi-structured interviews with senior health and sustainability professionals within the UK retail sector indicate that retailers have a diverse understanding of sustainable diets that seldom includes ‘less and better’ meat and dairy. Retailers are adopting a range of different strategies linked to ‘less and better’ meat and dairy – from improving the sustainability of their meat and dairy supply chains to influencing customer purchasing through ‘nudge’ interventions. While strategies related to ‘better’ meat and dairy are being adopted, no retailer is implementing interventions focused on reducing purchasing of meat products. The promotion of sustainable diets is seen by some retailers as a way of positively engaging with customers and improving brand loyalty, but there are external barriers to reducing purchasing of meat and dairy products that are beyond the direct control of the retailer.

JOANNA TREWERN, JONATHAN LEE CHENOWETH, IAN P CHRISTIE, Sarah Halevy (2022)Does promoting plant-based products in Veganuary lead to increased sales, and a reduction in meat sales? A natural experiment in a supermarket setting, In: Public health nutrition Cambridge University Press

Objective To explore changes in plant-based and meat product sales during and after implementation of a multi-component in-store intervention implemented by a major UK food retailer. Secondary objectives included exploring differences by store format and area affluence. Design The intervention increased the visibility, accessibility, affordability, and availability of a selection of plant-based products. Unit sales of plant-based and meat products during the intervention (January 2021) were compared with pre- (November 2020) and post-intervention (February & March 2021). Non-meat product sales were assessed as a control. Negative binomial mixed models were used to explore sales changes differences by store format or affluence. Setting The intervention was applied in a real-world supermarket setting during Veganuary. Participants Stores that applied the full intervention (n=154) were included for analysis. Weekly sales data for each store was obtained from the retailer. Results Average weekly unit sales of plant-based products increased significantly (57%) during the intervention period (Incidence Rate Ratio 1.52 [95% CI, 1.51-1.55]). Plant-based product sales decreased post-intervention but remained 15% higher than pre-intervention (IRR 1.13 [95% CI, 1.12-1.14]). There was no significant change in meat sales according to time period. The increase in plant-based product sales was greatest at superstores (58%), especially those located in below average affluence areas (64%). Conclusions Results suggest that increasing visibility, accessibility, affordability, and availability of plant-based products led to increased sales, with evidence of lasting effects. No significant changes in meat sales were observed. Variation according to store format and area affluence indicates targeted intervention approaches are needed.

JOANNA TREWERN, JONATHAN LEE CHENOWETH, Christie Ian (2022)“Does it change the nature of food and capitalism?” Exploring expert perspectives on public policies for a transition to ‘less and better’ meat and dairy, In: Environmental science & policy128pp. 110-120 Elsevier

To enable a transition to a more sustainable food future, it is crucial policymakers consider and address livestock production and meat consumption holistically. The concept of ‘less and better’ meat and dairy offers an alternative approach to industrial livestock production. This study explores perspectives of UK stakeholders engaged in political advocacy and implementation on policy priorities and specific policy measures aimed at facilitating a transition to ‘less and better’ meat in the UK. 16 UK experts on food and farming from the research, civil society, business and farming sectors were interviewed. Thematic analysis was conducted to identify convergence and divergence on views related to policy priorities and the potential for impact, political feasibility and unintended consequences of specific policy measures aimed at increasing the sustainability of livestock production or reducing meat consumption. Experts agreed on policy priorities but held divergent views on the potential for impact of specific policy measures. Economic structures including incentives, disincentives and food prices were highlighted as having the greatest influence over meat production and consumption practices.

JOANNA TREWERN, JONATHAN LEE CHENOWETH, IAN P CHRISTIE (2022)Sparking Change: Evaluating the effectiveness of a multi-component intervention at encouraging more sustainable food behaviors, In: Appetite171105933 Elsevier Ltd

Facilitating the adoption of more sustainable food behaviors is key in order to reduce pressure on nature and improve public health. Food businesses that interact directly with consumers are well placed to enable a positive change in food behaviors. The present study evaluates the effectiveness of a 9-week multi-component behavioral intervention implemented by a large UK food retailer. Three food behaviors were explored: meat consumption, food waste and scratch cooking. Evaluation methods comprise of surveys issued pre-intervention, at intervention-end and at delayed follow-up (3 months after intervention end), and focus groups where participants were divided according to life-stage (pre-family, family, retired). Results show the intervention mitigated individual barriers to change and had a positive impact on awareness, intention and behavior which lasted beyond intervention-end. Participants reported reducing their meat consumption and food waste and cooking more frequently from scratch. Findings indicate that the online community, ‘ask the expert’ videos and product samples were the most impactful intervention components, while recipes and cook-alongs were less effective. This study provides an effective and feasible intervention which could be implemented and scaled by food companies. While behavioral interventions offer a positive opportunity for companies to drive consumer behavior change, structural and cultural changes to the food environment will be needed to facilitate long-term change at scale.

Joanna Trewern, Luke Spajic, Theresa Lieb, Pramisha Thapaliya, Taylor Quinn, Roman Davas-Fahey, Omnia El-Omrani, Lana Weidgenant (2021)Youth demand political action on healthy sustainable diets, In: Nature Food2(10)pp. 746-747 Nature Research

There is an urgent need to transition to sustainable and nourishing dietary patterns. In the decade ahead, we will choose collectively either to accelerate or reverse a tide of diet-related chronic disease, climate change and species loss. Addressing food production through increasing efficiencies or transitioning to regenerative practices is clearly not enough1. Consumption patterns must shift to ensure food and nutrition security, and a liveable climate for a growing population.