Background: Adequate dietary intake can help prevent various cancers and other non-communicable diseases. People with a lower socioeconomic status often have less healthy diets than those with a higher socioeconomic status. To have a positive impact on public health, the NEXT STEP project aimed to strengthen the implementation process of three existing effective Dutch nutritional interventions for lower socioeconomic groups. These interventions are: PowerFood, an educational programme delivered by teachers to pupils in vocational secondary schools; Good Affordable Food, a community-based educational programme for adults on low incomes, delivered by course leaders who have completed an e-learning module; and Up for Cooking, a cooking course for adults with low health literacy and their children, delivered by trained lifestyle coaches and other professionals.
Objectives: The current study aims to examine the adoption, implementation and scaling up of these interventions to identify strategies that support implementation fidelity and to explore perceived barriers to and facilitators of successful implementation and scaling up.
Methods: From 2023 to 2025, adoption, implementation and scaling up of the three interventions was monitored using an action-oriented mixed-methods research approach with users and end-users. Adoption was examined through registrations on intervention websites and attendance data for intervention sessions. Participant responsiveness was explored through evaluation forms and observations. Interviews with implementers examined the implementation process, as well as perceived barriers and facilitators. Researchers' observations of intervention sessions examined implementation fidelity. Quantitative analyses were performed using descriptive statistics, while qualitative data were analysed using NVivo.
Results: The number of adopters increased to over 1,000 teachers for PowerFood, 64 course leaders for Good Affordable Food and 20 Up for Cooking course leaders. Participant responsiveness was high for all interventions. However, observations and interviews revealed that implementers had made significant changes, some favourable but some which compromised the programme's effectiveness. Course leaders found that acquiring resources to organise the course, recruiting participants and overcoming staffing challenges in schools were obstacles to implementation. Attractive, clear intervention materials provided valuable support. Successful strategies employed by the project team for scaling up included placing a touchscreen at recruitment locations to publicise PowerFood, holding online network meetings for Good Affordable Food course leaders and providing feedback on their implementation plans, and delivering train the trainer sessions for Up for Cooking and providing feedback on local implementations afterwards. Close collaboration with practitioners, network collaboration and motivated stakeholders all contributed to the successful scaling up of the interventions. However, low fidelity by implementers sometimes interfered with the effective components. Impeding factors included organisational changes at partner organisations, inadequate political support and a suboptimal scaling-up structure in the Netherlands.
Conclusions: In practice, monitoring and promoting the implementation and scaling-up process requires the project team to demonstrate continuous commitment and remain aligned with constantly changing regional and national implementation contexts. Although challenging, setting up and maintaining a quality assurance strategy is crucial, particularly without a sustainable national structure that supports funding. Action-oriented research, such as that conducted in the NEXT STEP project, can contribute to this.