The nutritional status of nurses working shifts: A pilot study in Turkey

Objective This study was carried out to determine the nutritional status of shift-working female nurses at a university hospital in Ankara, Turkey. Methods A total of 110 volunteer female nurses (n=56 control group, n=54 study group) were included in the study. A questionnaire with a three day food record collected the study data. Results The mean daily energy intake of the study group was higher than that of the control group (1756±659 kcal versus 1694±431 kcal, p>0.05). While the carbohydrate intake (196.3±85.5 g versus 185.9±54.7 g) and fat intake (79.5±29.5 g versus 77.1±22.6 g) were higher in the study group, the protein intake was higher in the control group (59.4±17.6 g versus 57.6±21.6 g). The mean iron intake was statistically higher in the control group (10.6±2.9 mg versus 10.0±4.0 mg, p<0.05). Conclusion To improve night shift workers’ performance and nutritional status it is important to provide accessible, healthy, and quality food services.


I N T R O D U C T I O N
Shift work is defined as scheduled work that is completed outside the parameters of the traditional day shift, which is usually considered to be between 6.00 and 18.00 1 .Shift work is prevalent across the world.In the United States, approximately 15% of full time workers are shift workers employed across a wide variety of industries and, in Europe, the figure is 20%.This number reaches 36% in China 2,3 and, in Turkey, 8% of the working population is composed of shift workers 4 .
Shift work is associated with several health, social, and security problems possibly due to an impairment of biological rhythms and a negative working environment 5 .Studies have shown that problems, such as gastrointestinal diseases, body weight changes, cardiovascular diseases, negative eating habits, lack of exercise, excessive caffeine consumption, and smoking are more common among shift workers [6][7][8][9][10] .These problems may derive from disruption to physiological, psychological, and social circadian rhythms 11 .
As people work irregular hours, their daily routine is interrupted.Regular eating and sleeping habits are difficult to maintain 12 .A regular meal time helps maintain a stable order in the circadian system, but in the 24 hours working period, especially in night shift working, regular eating is frequently abandoned.Even if there is no definition of nocturnal life, delayed sleeping and eating, and the irregular meal times due to shift working are considered important circadian rhythm disruptors 13 .The interruption of regular eating habits is more common among shift workers, in particular, during night work.Although calorie intake remains substantially unaltered compared with the day shift, the quality, quantity, and frequency of food eaten by shift workers differ.On the night shift they usually have quick meals, consisting of fast food, and increase their intake of caffeinated drinks, such as tea and coffee [14][15][16] .Night duty rotation is common practice in nursing.The nursing profession is staffed predominantly by women and has a work environment that is notable for its high work demands, and high levels of work stress and fatigue 17 .The number of nurses in Turkey is the highest among health care workers and the profession requires shift work.
The present study was carried out to answer the following questions: Do energy and macronutrient intakes differ between day shift and night shift?Is there a statistically significant change in eating patterns between day shift and night shift?Are health problems more common in night shift workers?The population of the study consisted of all nurses working in Gazi Hospital (n=824).Although the sample size was calculated as 87 individuals with 95% reliability (±5% deviation), it was targeted to reach more nurses.The shift work group consisted of 56 volunteer nurses, aged between 25 and 50 years, who had been shift working for more than one year.The day work group consisted of 54 nurses in the same age group who had been day working for more than one year.Pregnant nurses working day shift due to any health problem diagnosed by a doctor were excluded from the study.

M E T H O D S
The questionnaire was completed by the researchers face to face with the participants and took approximately 25 minutes to be completed.The questionnaire consisted of general properties, health status, information about shift work and a three-day food consumption record.The three consecutive food consumption logs were recorded using 24-hour recall by a professional dietitian for the control group on two consecutive weekdays and one weekend day, and, for the shift work group, pre-shift, post-shift and during the shift.Average intakes of energy, macro-, and micronutrients were calculated using the software BeBiS 7.2 (Nutrition Information System, Istanbul, Turkey).The program and data are evaluated by a comparison with the Dietary Reference Intakes (DRIs) 18 .
In the study body weight and height were measured by the researcher following the proper techniques 19 .Body Mass Index (BMI) was calculated by using the body weight/height 2 (kg/m 2 ) equation, and the World Health Organization (WHO) classification was used for evaluation 20 .
The level of physical activity was described as "sufficiently active" or "insufficiently active" with the help of a three-item short form used by Marshall et al. 21.Also, the mean amount of daily sleep was investigated.
All statistical analyses were performed using the Statistical Package for the Social Sciences (SPSS, Inc., Chicago, Illinois, United States) version 20.0.Data were expressed as mean and standard deviation or frequency and percentage.Descriptive data were expressed as number and percentage distribution.Chi-square distribution was used in relational investigations.The statistical significance was set at 0.05.
Participants were informed about the subject and the purpose of the study.Each nurse signed a voluntary participation form and filled in a questionnaire in accordance with the declaration of Helsinki (World Medical Association).This study was submitted to and approved by the Ethics Committees of Gazi University Faculty of Medicine (10/03/2014, Decision nº 135).

R E S U L T S
A total of 110 health workers (54 shift workers and 56 day workers) aged between 25 and 50 were included in the study.The mean age was 33.0±6.3years.The mean education level was 15.7±1.7 years, while the mean employment duration was 11.2±7.2years.The shift workers' smoking rate (39.3%) was significantly higher than that of day workers (37.0%) (p<0.05).The mean daily smoking amount was 12±6.3 cigarettes a day for a mean of 10.4±5.9 years, while the majority of individuals (70.9%) did not use alcohol.
In terms of physical activity, of all the individuals within the scope of the study, 10% were "sufficiently active" while 90% were "insufficiently active".No statistically significant difference was found between day workers and shift workers (p>0.05).
The study revealed that the mean sleep duration of the participants was 5.8±1.9 and that the mean sleep duration of the day workers (6.6±1.3 hrs) was significantly higher than that of shift workers (5.0±2.1 hrs) (p>0.05).
Shift workers (44.0%) reported more health problems than did day workers (37.0%).The most common problems reported were digestive disorders, musculoskeletal system problems, polycystic ovary syndrome, diabetes, and mental disorders.
The mean daily number of main meals was 2.5±0.5 and mean daily number of snacks was 1.9±0.8.The total number of main meals per day was significantly higher for day workers (2.8±0.5)than for shift workers (2.3±0.5)(p<0.001).The majority of shift workers (69.6%) skipped meals while only 22.3% of day workers skipped meals (p<0.001).
The mean daily B 1 , B 2, and B 6 vitamin intakes in both groups was similar while the mean daily intake of all other vitamins was higher for the day workers than for the shift workers, but the difference was not significant (p>0.05).Except for the mean daily intake of calcium and sodium, the intakes of all minerals were higher in day workers than in shift workers (Table 1   Vitamin C intake was adequate in shift workers (51.8%) but excessive in day workers (59.3%).Also, iron intake was more inadequate in shift workers (85.7%) than in day workers (66.7%) (p<0.05).There was no statistically significant difference between shift workers and day workers except for energy, vitamin C, and iron intakes (p>0.05)(Table 3).
Most participants (99.1%) eat away from home.Day workers frequently ate an afternoon meal (90.6%), while shift workers frequently ate an evening meal (83.9%).The frequency of eating at fast-food restaurants was higher in shift workers (7.1%) than in day workers (5.6%) (p>0.05)(Table 4).A total of 64.2% of the nurses eat away from home more than five times a week.Day workers eat away from home more often in a week than shift workers (5.5 times/week and 4.6 times/week, respectively) (p<0.001)(Table 4).

D I S C U S S I O N
One of the most important physiological problems attributed to shift work is the change in working, eating, and sleeping hours.The majority of the study individuals (94.6%) stated that their nutritional status was affected, and over half the subjects (53.6%) increased their food intake due to the changes in sleeping patterns during shifts.Previous studies have found that the quantity and frequency of food consumption in shift workers differed during the day.Night shift workers consumed meals in small quantities more than day workers during the day [14][15][16]22 . In his study the total number of main meals per day was significantly higher in day workers (2.8±0.5)than in shift workers (2.3±0.5)(p<0.001), and the majority of shift workers skipped meals, especially  1.9  Note: a More than one response was received, and the percentages were calculated according to number.
http://dx.doi.org/10.1590/1678-98652016000400013breakfast, for reasons such as feeling tired after the shifts and having brunch instead due to getting up late in the shift day.
In a prospective study by Knutsson et al. 23 , the frequency of consumption of high-carbohydrate snacks was higher in shift workers than in day workers.Another study found no statistically significant differences between day workers and shift workers in terms of energy and nutrient intakes 24 .In this study the mean daily energy and fat intakes were higher in shift workers than in day workers (p>0.05),but the mean daily protein intake was higher in day workers than in shift workers (p>0.05).A higher protein intake in day workers can be explained by the more frequent consumption of main meals.A lower mean number of main meals, despite the similarities in the mean amount of snack consumption in both groups, and the high consumption of high-fat and high-carbohydrate snacks during the night in shift workers results in higher energy, carbohydrate, and fat intakes.The ratio of saturated fatty acids and polyunsaturated fatty acids in the diet is a risk factor for cardiovascular disease, and the amount of energy from fat is considered an independent risk factor 25 .In this study the mean daily saturated fatty acid intake was higher in shift workers than in day workers.
Away-from-home consumption habits are increasing day by day.In this study almost all subjects (99.1%) ate meals away from home.Shift workers often ate an evening meal (83.9%) away from home while day workers often ate lunch (90.6%) away from home, and most of them preferred to eat at their work places' food services.Thus, to improve night shift workers' performance and nutritional status, it is important to provide accessible, healthy, and quality food services.Some behaviors for dealing with stress and staying awake for long working hours (smoking, high caffeine intake, eating more, etc.) can increase health risks.Shift work was defined as a risk factor for smoking habits 26 .In this study the proportion of smokers is significantly higher in shift workers (39.3%) than in day workers (37.0%) (p<0.05).
Vitale et al. 27 reported that irregular sleep was the most important reason for health problems among shift workers.In this study shift workers had more health problems than day workers, and sleep duration of shift workers was shorter.Regular physical activity contributes to the prevention and treatment of increased health problems resulting from exposure to shift work, and enables the individuals to acquire positive behavioral changes, thus helping to regulate the circadian rhythm 28 .
Griep et al. 29 found that exposure to night shift was linked to an increase in BMI.No statistically significant difference was detected between the two study groups in terms of BMI.However, taking into consideration that the physical activity level of 90% of the study individuals was "insufficiently active", obesity prevention strategies, such as increasing physical activity, can improve the nurses' health status.
Finally, future studies would benefit from an examination of the 'night eating syndrome', especially in night shift workers, and from the use of a 'shift work index' for better evaluation of the overall health, sleep quality, and nutritional status of shift workers.

R E F E R E N C E S
C O N T R I B U T O R SS NAVRUZ VARLI: Data collection and/or processing, analysis and/or interpretation, literature search, writing and critical reviews; S BILICI: Concept, design, supervision, writing and critical reviews. ).

Table 2 .
Evaluation of energy and nutrient intakes according to the Dietary Reference Intakes.

Table 3 .
Evaluation of total daily energy and nutrient intake adequacy.

Table 4 .
Distribution of away-from-home meals according to shift working.