Academic journal article Scandinavian Journal of Work, Environment & Health

Shift Workers Have a Similar Diet Quality but Higher Energy Intake Than Day Workers

Academic journal article Scandinavian Journal of Work, Environment & Health

Shift Workers Have a Similar Diet Quality but Higher Energy Intake Than Day Workers

Article excerpt

To serve the economic and societal demands of our 24/7 society, it is becoming increasingly necessary for employees to work outside the traditional daytime working hours. About 15-20% of employed adults in Europe and the USA currently work in shifts (1, 2). Shift work has, however, been linked with adverse health effects, including metabolic disturbances, such as alterations in body weight, glycaemia and lipids (3-6), and several chronic diseases, such as breast cancer, type 2 diabetes and cardiovascular diseases (6-9).

To alleviate these adverse health effects of shift work, there is a need for insight into the mechanisms that underlie this relationship. The causal mechanisms linking shift work and disease seem to be multifactorial. Lifestyle behaviors, such as poor dietary behaviors, have been hypothesized as one of the contributing factors of the adverse health effects of shift work (8, 10). Several studies have suggested that shift workers have poorer dietary behaviors than day workers (11, 12). During irregular shifts, shift workers tend to eat a larger number of small meals and eat more at irregular times (13, 14). As to their usual diet, shift workers seem to consume more high-energy snacks and sugars than day workers (14-17). Shift workers were also found to have a lower intake of fruits and vegetables (17, 18), fiber (19) and some vitamins and minerals (eg, vitamin B, C, magnesium) (19) than day workers. In contrast, one study has shown a higher consumption of fruits for shift workers in comparison with day workers (20), and other studies showed no differences for fruits and vegetables (21), vitamin C (18) and fiber (18, 22).

As pointed out in Lowden et al's review, most studies on shift work and diet had insufficient statistical power and used unreliable methods to measure nutrient and food intake (11). Most of these studies also lacked adjustment for major confounders, such as age (13-17, 19-24). Another important drawback is that the available studies focused on single nutrients or foods (13-24). For a comprehensive evaluation of differences in dietary intake, it is important to study dietary patterns because different nutrients and foods have additive and synergistic interactions (25). Overall dietary pattern scores, such as the Mediterranean Diet Score (MDS) or the World Health Organization (WHO)-based Healthy Diet Index (HDI), provide a broad picture of diet quality (25), and higher scores are associated with a lower risk of metabolic disturbances and chronic diseases (26, 27). In addition, a higher energy intake (ie, quantity of food) has also been associated with body weight gain and other metabolic disturbances (20, 28). Therefore, we hypothesized that shift workers have a poorer overall diet quality and higher energy intake than day workers. Dietary patterns may be more altered with a higher frequency of night shifts because night shifts desynchronize circadian rhythms and require the reorganization of food intake due to a changed sleep schedule (29). For that reason, we also hypothesized exposure-response relationships of a higher frequency of night shifts and years of shift work with poorer diet quality and higher energy intake.

Our aim was to compare quantity and quality of the usual diet between day and shift workers and to study exposure-response relationships regarding the frequency of night shifts and number of years of shift work.


Study population

The study comprised data from the Dutch part of the European Prospective Investigation into Cancer and Nutrition (EPIC-NL) that consists of the EPIC-MOR-GEN and EPIC-PROSPECT cohorts. The EPIC-MOR-GEN cohort comprises a general population sample of 22 654 men and women (participation rate: 45%) aged 20-65 years in 1993-1997 from three Dutch towns (Amsterdam, Maastricht, and Doetinchem). The EPIC-PROSPECT cohort consists of 17 356 women (participation rate: 35%) aged 49-70 who participated in a breast cancer screening program in Utrecht, the Netherlands. …

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