Introduction: This report examines whether variability in the type and amount of the nutrition intervention in a worksite-based intervention could explain dietary outcomes.
Methods: Data are from 55 intervention worksites in the Working Well Trial, a randomized controlled trial of worksite-based health promotion. The components of the nutrition intervention were kickoff event, direct education, interactive activities (e.g., food sampling), contests, printed information picked up by employees, and materials distributed to employees. We measured delivery of the nutrition intervention (i.e., dose) by determining the amount of workforce participation in each intervention component. Diet outcomes were changes in intakes of fat, fiber, and servings of fruits and vegetables (reported on food frequency questionnaires). All variables were aggregated to the worksite level. We correlated the dose variables with indices of receipt of the intervention and with the dietary outcomes.
Results: Contests were associated with employee awareness of and participation in the nutrition intervention (r = 0.49 and 0.28, respectively), and interactive activities were associated with intervention participation (r = 0.43). Contests were associated with increased fiber intake and fruit and vegetable consumption (r = 0.36 and 0.31, respectively), and direct education was associated with fruit and vegetable consumption (r = 0.38). All the above correlation coefficients were statistically significant (P < .05). Intervention dose was not associated with changes in fat intake.
Conclusions: It appears that longer, interactive intervention efforts (contests and classes) resulted in more positive outcomes than did one-time activities (such as the kickoffs) or more passive efforts (use of printed materials). There is a need for studies designed to test worksite- and community-based nutrition intervention methods.