OBJECTIVE: To examine the impact of a 6-month participatory and empowerment-based intervention study on employees' dietary habits and on changes in the canteen nutrition environment.

DESIGN: Worksites were stratified by company type and by the presence or absence of an in-house canteen, and randomly allocated to either an intervention group (five worksites) or a minimum intervention control group (three worksites). The study was carried out in partnership with a trade union and guided by an ecological framework targeting both individual and environment levels. Outcome measures included: (i) changes in employees' dietary habits derived from 4 d pre-coded food diaries of a group of employees at the worksites (paired-data structure); and (ii) the canteen nutrition environment as identified by aggregating chemical nutritional analysis of individual canteen lunches (different participants at baseline and at endpoint).

SETTING: Eight blue-collar worksites (five of these with canteens).

SUBJECTS: Employees.

RESULTS: In the intervention group (n 102), several significant positive nutritional effects were observed among employees, including a median daily decrease in intake of fat (-2.2 %E, P = 0.002) and cake and sweets (-18 g/10 MJ, P = 0.002) and a median increase in intake of dietary fibre (3 g/10 MJ, P < 0.001) and fruit (55 g/d, P = 0.007 and 74 g/10 MJ, P = 0.009). With regard to the canteen nutrition environment, a significant reduction in the percentage of energy obtained from fat was found in the intervention group (median difference 11 %E, P < 0.001, n 144).

CONCLUSIONS: The present study shows that moderate positive changes in dietary patterns can be achieved among employees in blue-collar worksites.