Successful Design, Implementation and Evaluation of Nutrition Intervention Research

Background: Nutrition trials are important for informing our dietary and clinical guidelines. Central to the success of these trials is participant adherence to dietary behaviours asked of them. Despite its importance, trials commonly experience challenges with adherence, and the empirical knowledge in the ways researchers design trial components to support adherence is scant. Behaviour change science is the field studying why and how behaviour change can be brought about. The theories and frameworks within it have been used to improve the design and effectiveness of health behaviour interventions, as well as to improve trial behaviours, such as participant retention. Hence, using such frameworks provides a promising avenue to also support participant adherence. Aims: The aims of this thesis are to (i) investigate the feasibility and effectiveness of using behaviour change frameworks to support participant adherence to dietary behaviours, and (ii) elucidate if and how researchers consider supporting participant adherence to dietary behaviours and their relationship to using behaviour change science when designing trials. Methods: This thesis consists of three independent studies. The first two address aim (i) and were nutrition intervention trials that employed different behaviour change frameworks to support participant adherence; the Protein Diet Satisfaction (PREDITION) trial used The Nine Principles Framework to support young adults to adhere to a healthy, vegetarian diet, while the He Rourou Whai Painga trial used the Behaviour Change Wheel to support participants at risk of metabolic syndrome to consume a New Zealand-adapted Mediterranean Diet for 12 weeks. Within these trials, outcomes measured included adherence to target behaviours, engagement with support components, change in perceived barriers to performing behaviours, and impact evaluations. The final qualitative study addressed aim (ii) in which researchers participated in semi-structured, one-on-one interviews to identify themes in current practice and beliefs regarding how they design trials to support participant adherence, and their perceived barriers and enablers to using behaviour change science in the design of nutrition trials. Results: Adherence to targeted dietary behaviours was improved for both the PREDITION and He Rourou Whai Painga trials between baseline and primary outcome timepoint, despite relatively low engagement with online components, particularly those delivered via Facebook. The frameworks enabled systematic selection of behaviour change techniques to address perceived barriers; this method contrasted to the findings of the qualitative study which highlighted that, although researchers are motivated to encourage participant adherence to dietary behaviours, trial components to support this are chosen based on experience and non-systematic practice. Regarding using behaviour change science when designing trials, some researchers felt this would be beneficial, but lacked the knowledge and skills to do so, while others were sceptical of its value over current experience-based practice. Conclusion: Using behaviour change frameworks in the design of nutrition trials to support participant adherence to dietary behaviours is a feasible and promising method. However, more research that directly compares this method to current practice is warranted.

Name thesis:degree_name

PhD

Level thesis:degree_level

Doctoral

Discipline thesis:degree_discipline

Nutrition and Dietetics

Grantor dc:publisher

ResearchSpace@Auckland

Year dc:date.issued

2024

Author dc:creator

• Worthington, Anna

Advisor dc:contributor.advisor

• Braakhuis, Andrea

• Behaviour change
• Behaviour change wheel
• Nutrition
• Dietetics
• Behaviour change framework
• Mediterranean Diet
• Dietary change

Statement dc:rights

• Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated.

Licence dc:rights.uri

• https://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm

Handle dc:identifier.uri

https://hdl.handle.net/2292/74270

OAI identifier oai:identifier

oai:researchspace.auckland.ac.nz:2292/74270