Workers spend long hours at the workplace, limiting opportunities to learn about healthy lifestyles and nutrition. A multimodal nutrition intervention can thus improve their health factors. This study showed that after 6 months, mean weight, BMI, total cholesterol, LDL cholesterol, triglycerides, systolic and diastolic blood pressure significantly decreased, while HDL cholesterol increased (p < 0.001). However, fasting blood sugar and liver enzymes did not change significantly.
In line with these results, Hassani et al. reported significant reduction in weight and BMI after three months of nutritional education among workers with dyslipidemia, though their intervention was shorter and limited to education [20]. A systematic review of 23 studies, confirmed the efficacy of workplace weight management programs. It is noteworthy that a majority of the studies reviewed predominantly originated from North America and Europe, reflecting a concentrated geographic focus on these continents. [21]. Also a meta-analysis study investigated the effect of dietary interventions in the workplace on obese and overweight employees, the results of which indicated a significant reduction in weight, BMI, and total cholesterol and a non-significant reduction in systolic and diastolic blood pressure [22]. Another study showed that the worksite wellness program improves blood pressure and total cholesterol control, but has no improvement in weight control [11]. In another study involving a 4-month nutritional education intervention with 75 male workers, the findings indicated a significant reduction in fasting blood glucose levels, total cholesterol, and LDL cholesterol after the intervention was implemented [17]. In their assessment of nutritional interventions conducted in the workplace, Steyn and colleagues concluded that interventions focusing on altering nutritional knowledge and dietary behaviors lead to improved health and employee behaviors [23]. On the other hand, in the study of Song et al., although the multicomponent workplace wellness program improved some behavioral factors, no significant changes were observed in clinical factors including blood glucose levels, blood cholesterol levels, blood pressure, and BMI [24]. Like the present study, the results of other studies show the effect of these interventions on the mentioned factors, although some contradictions in the results can be explained by the difference in the methods of the interventions, the duration of studies and the number of participants.
Contrary to expectations, no significant decrease in fasting blood sugar of the participants was observed in the current study. It seems that the high impact of food intake the day before the blood test on this factor can justify it. If the amount of hemoglobin A1 C, which is less influenced by people’s recent food intake, was measured, more complete results would be obtained.
One of the aspects of our intervention was nutrition education for the workers. Nutrition education interventions have been shown to increase nutritional awareness among workers in various studies. Workplace-based nutrition education, such as integrating nutrition education, improving factory canteen services, and enhancing health services, effectively enhances workers’knowledge and practices of balanced nutrition and healthy habits [15]. Nutrition counseling was one of the other aspects of the present study. Workplace nutritional interventions, including counseling by Registered Dietitian Nutritionists (RDNs), have been associated with positive impacts on dietary habits and weight loss among employees [25]. Additionally, nutritional counseling has been found to contribute to reductions in anthropometric measurements, glycemia indices, lipid profiles, and insulin resistance, ultimately improving overall health indicators [26]. Another of our interventions was the nutritional improvement of the company’s food menu. Modifying the factory food menu can significantly impact workers’health factors [27]. Implementing nutritional interventions and changes in the food service system can lead to improved weight management among staff, as evidenced by a decrease in BMI and weight in the intervention group [28]. Additionally, the satisfaction level with the food service increased following menu modifications, indicating a positive impact on workers’dietary habits and overall well-being [29]. Therefore, optimizing the factory food menu through nutritional interventions and system-level modifications can contribute to enhancing workers’health and well-being, ultimately benefiting both employees and employers.
The current study has several advantages. Unlike many studies in this field, which limit themselves to one-dimensional intervention, in this study, we tried to achieve the maximum effect by using education, counseling, and diet changes by creating a multimodal intervention. Providing nutrition education to the workers’families was also one of the strengths of this study, which, considering the important role of the family in the workers’lifestyle, helped them to comply more with the intervention. In the present study, all educational programs, consultations, interviews, and measurements were done by a trained physician and registered dietitian. Also, all the biochemical parameters were measured by trusted laboratories and checked again by the physician. The type of this study is prospective follow-up and has an acceptable sample size compared to similar studies in this field. The study maintained a high retention rate, with only 4 out of 1097 participants (0.36%) excluded due to cancer diagnosis and none due to leaving employment, both unrelated to the nutritional intervention, suggesting minimal risk of attrition bias. However, this investigation had several limitations. The absence of a control group in this study is one of these issues which prevents definitive attribution of all observed changes to the nutritional intervention alone. This was unavoidable due to ethical and practical considerations, and historical control data from similar populations were unavailable. To address this, we calculated effect sizes (Cohen’s d) for all continuous outcomes, which ranged from small to medium (Tables 3 and 4). These consistent and meaningful effect sizes suggest that the observed improvements in anthropometric and laboratory parameters are unlikely to result solely from natural variation or unmeasured confounders, supporting the intervention’s effectiveness. Nevertheless, without a control group, alternative explanations (e.g., temporal trends) cannot be fully ruled out, and future studies with comparative designs could further confirm these findings. Furthermore, the lack of evaluation of participants’dietary intake and their nutritional knowledge before and after the intervention is acknowledged. While our study did not include formal assessments of dietary changes using methods such as food frequency questionnaires or dietary recall, this limitation impacts the direct correlation between observed health improvements and specific dietary modifications. To enhance future research in this area, incorporating comprehensive dietary assessments like food frequency questionnaires or dietary recall methods is recommended. A notable limitation of our study is the absence of hemoglobin A1 C (HbA1c) measurements, which could have provided valuable insights into long-term glycemic control. Unfortunately, due to resource constraints, we were unable to assess HbA1c levels in this study. we recommend that future studies prioritize the inclusion of HbA1c measurements to enhance the depth of analysis and strengthen the robustness of conclusions drawn regarding glycemic status. The study focuses on male workers (> 99%) due the factory’s predominantly male workforce, not intentional bias,, potentially limiting the generalizability of the findings to female populations. It is important to acknowledge this demographic imbalance as a notable limitation. Future research efforts could aim to include a more diverse sample to enhance the overall applicability and relevance of the study’s outcomes across different gender groups. A limitation of this study is the lack of adjustment for potential time-varying confounders. However, given the uniform application of the nutritional intervention across the entire population and the absence of reported external influences, we believe the impact of such factors was minimal.
The findings of this study show the significant effect of multimodal nutrition intervention on the improvement of anthropometric indicators and lipid profiles of Arfa Iron and Steel Company workers. These results suggest that implementing similar interventions (encompassing nutritional education, modification of the factory dining menu to include healthier options, healthy cooking method education, and nutritional counseling) in similar industrial settings may have the potential to improve the overall health and well-being of workers, potentially enhancing their productivity levels. The positive outcomes observed in this study highlight the feasibility of such interventions as a health promotion strategy within comparable occupational contexts. However, given the absence of a control group and other methodological limitations, broader application to diverse workplace environments should be approached cautiously. Further research incorporating control groups and extended follow-up periods is essential to validate these findings and assess the sustained effectiveness of such interventions across varying work settings.