The aim of this study is to test the efficacy, feasibility, and acceptability of a novel, behaviour-focused personalised nutrition intervention compared to a control personalised nutrition intervention for improving adherence to sustainable and healthy dietary recommendations in university students.

Participants will be recruited from the University College Dublin (UCD) PLAN'EAT Living Lab (LL) Citizen Panel which will form a separate registration. The UCD PLAN'EAT LL is a series of studies designed to develop, implement, and evaluate strategies to support University students' transition towards a sustainable healthy diet. The UCD PLAN'EAT LL study will recruit up to n=500 healthy students (aged 18-30 years) attending UCD, Belfield Campus, to join the UCD PLAN'EAT LL Citizen Panel. Upon successful screening and completion of informed consent, participants will be invited to join the UCD PLAN'EAT LL Citizen Panel and complete initial baseline data collection measures (which will be detailed in a separate registration). Following completion of this baseline data collection, participants within the UCD PLAN'EAT LL Citizen Panel will be subsequently invited to participate in this study detailed below.

Participants within the UCD PLAN'EAT LL Citizen Panel will be invited to participate in a 4-week study. This study will aim to recruit n=40 participants within the UCD PLAN'EAT LL Citizen Panel. After successful screening and informed consent, participants will be randomised into two separate groups (n=20 control group; n=20 intervention group) receiving different types of personalised recommendations and strategies using decision tree algorithms to support them to consume a healthier and more sustainable diet. The control group will receive a personalised dietary plan and standardised behavioural support (based on previous personalised nutrition trials and usual care in dietetic practice) to meet their personalised dietary recommendations. The intervention group will receive the same as the control group, with the addition of receiving personalised behavioural support and strategies to help them meet their personalised dietary recommendations.

Baseline: Participants will be asked to complete a questionnaire including questions on demographics, health, dietary behaviours, and lifestyle and a dietary assessment. The dietary assessment will include 3 online 24-hour dietary recalls (2 non-consecutive weekdays and 1 weekend day) (via the web-based dietary recall tool, Foodbook24).

Following completion of baseline measures, participants will be invited to attend a study visit in UCD. Participants will undergo a diet counselling session, where they will receive a personalised feedback report and advice from a nutritionist on how to achieve their goal of eating a more sustainable and healthy diet.

Midpoint: Participants will be contacted by a member of the research team via email or phone message to check their progression and to address any queries.

Endpoint: At the end of the 4-week study, participants will complete a diet-related questionnaire and a second dietary assessment. The dietary assessment will include 3 online 24-hour dietary recalls (2 non-consecutive weekdays and 1 weekend day) (via the web-based dietary recall tool, Foodbook24).

Following completion of endpoint measures, retention rates (number of participants who complete endpoint measures / number of participants enrolled into the study x 100) and data completion rates (number of complete datasets for each outcome measure / number of participants enrolled ×100) will be calculated to assess study feasibility and acceptability.

Process Evaluation:

At the end of this study, all participants will be invited to complete a study evaluation questionnaire including feasibility, acceptability, and engagement measures. In addition, a subsample of participants will also be invited to participate in focus groups or one-to-one interviews to explore topics on study feasibility encompassing, for example, their study experience, study acceptability, factors affecting participation rates (e.g., barriers/ enablers), study engagement, and suggestions for improvement. The focus groups or one-to-one interviews will be guided by the APEASE (Acceptability, Practicality, Effectiveness, Affordability, Side-effects, Equity) criteria.

Student Participants:

Inclusion Criteria:

• Be a UCD student (aged 18-30 years) attending Belfield Campus.
• Be an adult between the age of 18-30 years old, and in general good health.

Exclusion Criteria:

• Do not attend UCD Belfield Campus.
• Are under 18 years of age or over 30 years of age.
• Have a diagnosis of an acute or chronic medical condition that could interfere with the outcomes of the study. Such diagnosis include (but not limited to) cardiovascular disease, diabetes mellitus, cancers (within the past 5 years), etc.
• Are pregnant, lactating or planning to become pregnant.
• Are following a medically prescribed diet.
• Are immunocompromised or have a suspected immunodeficiency.
• Have a known food allergy.
• Taking part in another diet-related research study that could interfere with the outcomes of this study
• Consume ≥2 servings per day of legumes.

At the beginning of the study, each participant will have a study code assigned to them. All data collected from the study will be stored using these unique study codes. A file will be set up which will be stored in a separate location to the study data. This file will contain a list which will link each participants contact details to the corresponding ID code. All stored information will be password-protected and only accessible to the research team/ named researchers on the project. Pseudonymised/ anonymised data will be shared with PLAN'EAT partners where appropriate.

Single-blinded parallel study