Background Although the workplace is a potentially important setting to influence dietary behaviours, evidence on effective interventions is limited. The study aim was to assess the comparative effectiveness of a workplace environmental dietary modification intervention and an educational intervention both alone and in combination versus a control workplace on employees’ dietary behaviours, nutrition knowledge and health status.
Methods In the Food Choice at Work cluster controlled trial, four large, purposively selected manufacturing workplaces were allocated to A, (Control), B, nutrition education alone (Education), C, environmental dietary modification alone (Environment) and D, nutrition education and environmental dietary modification (Combined intervention). Nutrition education included: group presentations, individual consultations and detailed nutrition information (traffic light menu-labelling, posters and emails). Environmental dietary modification included: menu modification (restriction of fat, saturated fat, sugar and salt), increase in fruit and vegetables, price discounts for fruit, strategic positioning of healthier alternatives and portion size control. Data on dietary intakes (24-hour dietary recalls and food frequency questionnaires), nutrition knowledge (validated questionnaire tool), BMI, waist circumference and blood pressure were obtained at baseline and follow-up at 7–9 months. The Dietary Approaches to Stopping Hypertension (DASH) score was used as a composite measure of diet quality. Analysis of covariance was used to compare changes between baseline and follow-up across the four groups with adjustment for age, gender, educational status and other baseline characteristics.
Results At baseline, 850 employees aged 18–64 years were recruited with N (response rate%) in each workplace as follows: A-control: 111(72%), B-Education: 226(71%), C-Environment: 113(91%), D-Combined intervention: 400(61%). Complete follow-up data was obtained for 517 employees (61%). There were significant positive changes in intakes of saturated fat (p = 0.013), salt (p = 0.010) and nutrition knowledge (p = 0.009) between baseline and follow-up in the combined intervention versus the control workplace in the fully adjusted multivariate analysis. Small but significant changes in BMI (–1.4kg/m2 (95% CI –2.447, –0.346, p = 0.047) were observed in the combined intervention. Changes in the DASH score (p = 0.028) were only significant when adjusted for age and gender. No significant changes in waist circumference and blood pressure were observed. Effects in the education alone and environment alone workplaces were smaller and generally non-significant.
Conclusion The ‘Food Choice at Work’ combined intervention represents a potentially viable model that is effective and feasible in a large workplace setting. However, it needs to be fully tested using an optimal randomised controlled trial design and full-scale evaluation to provide robust evidence for policy makers.
Current Controlled Trials: ISRCTN35108237.
- complex workplace dietary interventions
- cluster controlled trial
- environmental dietary modification
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