Journal List > J Nutr Health > v.49(5) > 1081461

Yim and Lee: Relationships between job stress and caffeine intake in industrial workers



This study analyzed the degree of job stress and caffeine intake in workers in industrial positions in order to determine the relationships between job stress and caffeine intake.


For this purpose, this study conducted a survey targeting 361 blue collar workers working for K manufacturing company, Gwangju.


The total score for job stress in subjects was 72.7 ± 6.8 points/100 points. According to job stress, subjects were categorized as follows: Q1 for the group who had the least stress; Q2 for the group who had little stress; Q3 for the group who had a lot of stress, and Q4 for the group who had the most stress. As for the effects of caffeine on health, 57.1% thought that caffeine is helpful and not harmful if taken properly while 17.3% responded that less caffeine consumption is better. Daily intake of caffeine according to stress was presented as: 172.0 ± 85.3 mg in Q1, 179.0 ± 83.7 mg in Q2, 187.9 ± 81.4 mg in Q3, and 214.2 ± 147.3 mg in Q4 (p < 0.05). The percentages of caffeine consumption compared to the daily safe limit in subjects were: 43.0 ± 21.3, 44.8 ± 20.9, 47.1 ± 20.4, and 53.6 ± 36.8% in Q1, Q2, Q3, and Q4, respectively (p < 0.05). Adverse effects such as nausea or vomiting from caffeine were most common in Q4 (p < 0.05)


As a result, higher stress in blue collar workers working for K manufacturing company was associated with more caffeine consumption. Groups with a lot of stress (Q4) consumed approximately 50% of daily safe limit of caffeine. Considering the results above, this study suggests that further research on more precise caffeine intake and its effects is needed.

Figures and Tables

Table 1

General characteristic of subjects n (%)


1) Mean ± SD

Table 2

Job stress degree


1) Mean ± SD

Table 3

Anthropometry investigation according to the job stress levels n (%)


1) Job stress levels: sum for job stress's Q1 ≤ 25%, Q2: 26 ~ 50%, Q3: 51 ~ 75%, Q4 ≥ 76% 2) BMI (body mass index) = weight (kg) / height (m)2 3) Mean ± SD 4) Obesity: BMI < 18.5, normal: 18.5 ≦ BMI < 23.0, overweight: 23 ≦ BMI < 25.0, obesity: 25.0 < BMI

Table 4

Healthy behaviors according to the job stress levels n (%)


1) Job stress levels: sum for job stress's Q1 ≤ 25%, Q2: 26 ~ 50%, Q3: 51 ~ 75%, Q4 ≥ 76%

*p < 0.05, **p < 0.01

Table 5

Caffeine awareness according to the job stress levels n (%)


1) Job stress levels: sum for job stress's Q1 ≤ 25%, Q2: 26 ~ 50%, Q3: 51 ~ 75%, Q4 ≥ 76%

*p < 0.05

Table 6

Caffeine intake according to the job stress levels


1) Job stress levels: sum for job stress's Q1 ≤ 25%, Q2: 26 ~ 50%, Q3: 51 ~ 75%, Q4 ≥ 76% 2) Mean ± SD 3) Different letters denote significant difference at p < 0.05 by Tukey's test within the row. 4) Ministry of Food and Drug Safety (2013)18

*p < 0.05, **p < 0.01, ***p < 0.001

Table 7

Adverse effects from caffeine intake according to the job stress levels


1) Job stress levels: sum for job stress's Q1 ≤ 25%, Q2: 26 ~ 50%, Q3: 51 ~ 75%, Q4 ≥ 76% 2) Mean ± SD 3) Score: 1 = rarely, 3 = sometimes, 5 = mostly

*p < 0.05

Table 8

Pearson's correlation coefficients between caffeine intake and general characteristics of subjects


*p < 0.05, **p < 0.01


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