Bewust eten, hoe doe je dat?
Evaluation of an online intervention aimed to promote healthy eating among higher and lower socioeconomic groups.

Background:

Unhealthy dietary patterns are very prevalent among Dutch adults. People consume too much (saturated) fat and high-energy snacks and too little fruit and vegetables. Unhealthy dietary patterns are even more prevalent in low socio-economic (SES) groups. Unhealthy dietary patterns are an important risk factor for multiple diseases, which have a large impact on public health. Therefore, it is important to improve dietary patterns in the Netherlands, especially among low SES groups.

Computer-tailored interventions have found to be efficacious in improving dietary behaviors. The effect sizes of these interventions are, however, mostly small. Most tailored interventions predominantly target individual determinants like attitudes and self-efficacy. The efficacy can potentially be improved by tailoring on ‘new’ determinants, such as environmental factors. Environmental factors, such as availability and prices of healthy food options, are thought to be important determinants of dietary behavior.



Objective:

The objective of this study is to evaluate two versions of an internet-delivered computer-tailored intervention aimed at reducing (saturated) fat and high-energy snack intake and increasing fruit and vegetable consumption among Dutch adults from various SES backgrounds.



Intervention:

Both versions are based on the self-regulation theory.

Basic intervention: The basic intervention provides feedback on behavior (awareness), individual cognitions (like attitude and self-efficacy) and on volitional processes (like goal-setting and action-planning). Also, monitoring and evaluation of the progress towards achieving the stated goals are included.

Extended version: In addition to the strategies included in the basic version of the intervention, the extended version also provides environmental feedback. In this version of the intervention feedback is provided on availability and prices of healthy food options in the supermarkets that people usually go to. The aim is to improve awareness of the availability of healthy food options and improve self-efficacy for choosing and eating healthy foods. In addition feedback is provided on how to make changes in the home food environment, in order to make this more supportive for healthy eating.



Evaluation:

The effects of the intervention will be evaluated in a three group (basic version intervention, extended version intervention, generic information control group) randomized controlled trial including 1.400 Dutch adults. Assessment will be at baseline, 1, 6 and 12 months post-intervention. Primary outcome will be self-reported dietary intake.

1. Both tailored interventions will result in better outcomes on self-reported fruit, vegetable, high-energy snack and fat intake, than the generic information control group;

2. Both tailored interventions will result in better outcomes on secondary variables (i.e. self-reported BMI, self-control and self-regulation skills) than the generic information control group;

3. Both tailored interventions are expected t o result in better outcomes on mediating variables (i.e. motivational determinants of the dietary behaviors (awareness, attitude, subjective norm, perceived behavioral control), habit for the recommended behaviors, planning-self efficacy, coping self-efficacy, perceived availability of healthy food products in the neighborhood, and adaptations in the home food environment than the generic information control group;

4. The tailored intervention with environmental feedback will result in better outcomes than the basic intervention;

5. Effects will be most pronounced at the one and six month post-tests;

6. Both versions of the intervention will be effective among the higher and the lower SES groups;

7. The intervention effects are mediated through the motivational determinants of the dietary behaviors (awareness, attitude, subjective norm, perceived behavioral control), planning and perceived availability of healthy food products in the neighborhood.



Moderation of the intervention effects through other demographic characteristics, individual cognitions and planning will be explored.

1. T0: Start;

2. T1: 1 month after intervention;

3. T2: 6 months after intervention;

4. T3: 12 months after intervention.

Bewust eten, hoe doe je dat?



Experimental conditions:

1. Basic version: Web-based computer-tailored program to increase intake of fruit and vegetables and to reduce intake of high-energy snacks and fat. The program targets motivational factors (e.g. awareness, attitude, perceived behavioral control) and self-regulation processes (goal setting, action planning, coping planning);

2. Extended version: Web-based computer-tailored program that is identical to the basic version, but in addition provides feedback on availability and price of healthy products in the supermarket the participants usually visits (environmental feedback).



Control condition:

The control group will receive web-based generic information on fruit, vegetables, high-energy snacks and fat consumption.