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Table 4 Main concepts and measures in the Boost study

From: The Boost study: design of a school- and community-based randomised trial to promote fruit and vegetable consumption among teenagers

Concepts

Operationalization/definition

Pupil Parent Principal

Teacher (PE)*

Observations/photos

Local provider (PE)*

Manager youth club*

Manager sports club*

Coach sports club*

FG* (PE)

CT* (PE)

Distal outcome**:

            

Adolescents' FV intake (amount)

24-hour recall questionnaire (converted to grams per day)

X

          

Adolescents' usual FV intake

FFQ

X

          

Proximal outcomes**:

            

ENVIRONMENTAL DETERMINANTS

Actual and perceived availability:

Covered dimensions: quantity, variety, quality, appearance, accessibility, convenience, parental facilitation, visibility, time for eating FV, access to unhealthy food

           

at school

(see dimensions above)

X

X

X

X

X

X

   

X

X

at home

(see dimensions above)

X

X

         

in the leisure time

(see dimensions above)

X

X

    

X

X

X

  

in the (school-) neighbourhood

(see dimensions above)

X

X

X

 

X

      

SOCIAL DETERMINANTS

Social norms: situational norms

Number of meals, situations, occasions and settings perceived as appropriate for eating FV

X

X

         

Parental influence

            

Dietary knowledge

Knowledge of national FV recommendations

 

X

         

Attitude

Perceived importance of child eating FV

 

X

         

Actual and perceived FV intake

FFQ/24-hour recall questionnaire similar to distal outcome

X

X

         

Usual intake of unhealthy food

Intake of soft drinks, sweets and salty snacks (FFQ)

 

X

         

Modelling

If parents are eating FV together with children

X

X

         

Perceived barriers

Access, time, money, convenience, preparation skills

 

X

         

Peer influence

FV intake

If best friends are eating FV

X

          

Social norms: peer norms

If it is 'cool' to eat FV in school class. If the majority of peers are eating FV in school and in the leisure time

X

        

X

 

Teacher influence

Modelling

How often teachers eat delivered FV together with pupils

   

X

     

X

 

Attitude

Perceived importance of promoting healthy eating in school

   

X

     

X

 

Sport coach influence

Modelling

If sports coaches are eating FV during practice

      

X

    

Attitude

Perceived importance of children eating FV during practice

      

X

    

Proximal outcomes**:

            

PERSONAL DETERMINANTS

Taste preferences

Liking of FV and number of different FV liked

X

         

X

Dietary knowledge

Knowledge of national FV recommendations

X

          

Awareness

Awareness of whether they meet national recommendations

X

         

X

Short term outcome expectations

Perceived immediate effects of eating FV: e.g. more energy, feel better, FV not filling enough, FV allergy

X

          

Potential positive side effects:

          

X

 

More energy

Loss of energy during the school day

X

  

X

     

X

 

School concentration

Unable to concentrate during class lessons

X

  

X

     

X

 

Wellbeing

Children's level of life satisfaction, if they most of the time are feeling well and full of energy

X

  

X

       

Usual intake of unhealthy food

Intake of soft drinks, sweets and salty snacks (FFQ)

X

          

School: environmental changes

Nutrition policies, FV programme, food availability

 

X

  

X

      

Unintended adverse outcome:

          

X

 

Bullying

How often they have been bullied at school in the past couple of months

X

          

Weight- and eating related teasing

If class mates are teasing each other because of weight, lunch bags or eating habits

X

          

School class thriving

If pupils in their class enjoy being together

X

          

Free FV replace FV eaten at other times of the day**

Eating less FV at home (24-hour recall questionnaire). Fewer children bringing FV to school from home

X

X

       

X

 

Moderators:

            

Socioeconomic position

Parent occupational social class

X

X

         

Socioeconomic position

Parental education

 

X

         

Gender

Boys and girls

X

          

Implementation degree

Dose delivered/received, fidelity: adherence to protocol

X

X

X

X

X

X

X

X

X

X

X

  1. Abbreviations: CT = Computer tailoring, FG = focus groups with children and/or teachers, FV = fruit and vegetables, PE = process evaluation, * at intervention schools only, **measured for fruit and vegetables separately