What this Trial Is About

Inadequate plant food intake is a leading modifiable risk factor for non-communicable disease. However, on average, 88% of individuals do not consume adequate amounts of vegetables. Using digital technology may help improve health behaviours , with this potentially providing an accessible route to increasing plant food intake. However, uptake and engagement with applications designed to influence health behaviours is generally poor , and few studies have examined the main factors supporting user engagement and retention. Personalised dietary feedback, such as the provision of personalised advice or recipes, has the potential to enhance this process. However, whether nutritional interventions utilising personalised dietary feedback support user interaction, engagement, and retention remains to be studied. Hence, the proposed project is a proof-of-concept study aiming to assess the effectiveness of using an application with personalised dietary feedback to support increased healthy plant food intake. 315 healthy males and females, between the ages of 18- and 45-years who self-report less than 50% of the recommended intake of vegetable consumption will participate in the study. Before the intervention, participants will receive web-based instruction on the use of the smartphone application. Subsequently, participants will log all meals for two-weeks using the application to generate a baseline plant food consumption profile. In the baseline period, participants will wear a continuous glucose monitor. This will inform their individualised goals and possible feedback for the intervention period. The intervention will be 4-weeks in duration, consisting of the use of a personalised dietary program application, which will provide both recipes and feedback. Those randomised to the control will only have access to the meal logging feature. Throughout this period, participants will wear a smartwatch to track sleep metrics such as sleep onset and duration. Following the four-week intervention period, participants will be able to continue using the app for a six-week period, during which engagement with the application over time will be ascertained via telemetry. At the end of the follow-up, participants will receive an exit questionnaire to provide insight on their experience with the application, attitudes, habits and knowledge regarding consumption of plant foods, and self-perceived impact on health and dietary habits. To provide mechanistic insight, a subset of participants (n = 50) will visit the laboratory at the University of Bath on two occasions (approximately 45 minutes each) - baseline and post-intervention. During laboratory visits, participants will provide blood pressure and body weight measurements, as well as saliva and venous blood samples. Saliva samples will be assessed for salivary cortisol, and blood samples will be assessed for the following: plasma glucose \& insulin; plasma uric acid; plasma ascorbic acid; plasma tocopherols; serum carotenoids; plasma cytokines; plasma CRP and ferritin; F2-Isoprostanes; immune cell inflammatory capacity; HbA1c.

Can Personalised Digital Feedback Help Increase Plant Food Intake?