Table 1. Characteristics of study subjects.
| Workplace A (July) | Workplace B (November) | P valueb | ||||||
| Men | Women | P valuea | Men | Women | P valuea | Men | Women | |
| No. of participants | 100 | 61 | 212 | 156 | ||||
| Age (years) | 44.8 ± 10.8 | 40.5 ± 9.8 | 0.01 | 44.3 ± 10.8 | 41.2 ± 10.8 | <0.01 | 0.67 | 0.68 |
| Body mass index (kg/m2) | 24.3 ± 3.5 | 20.7 ± 2.8 | <0.01 | 23.2 ± 3.1 | 21.2 ± 3.3 | <0.01 | <0.01 | 0.27 |
| Occupation (office work, %) | 93.0 | 55.7 | <0.01 | 87.3 | 71.2 | <0.01 | 0.13 | 0.03 |
| Cigarette smoking (current, %) | 43.0 | 3.3 | <0.01 | 44.3 | 2.6 | <0.01 | 0.82 | 0.77 |
| Alcohol intake (≥20 g/d, %) | 32.0 | 4.9 | <0.01 | 34.4 | 7.7 | <0.01 | 0.67 | 0.47 |
| Non-job physical activity (≥2 h/wk, %) | 46.0 | 18.0 | <0.01 | 42.0 | 23.7 | <0.01 | 0.50 | 0.36 |
| Dietary intake (/day) | ||||||||
| Vitamin D (µg/1000 kcal) | 6.1 ± 3.3 | 6.7 ± 3.4 | 0.33 | 6.2 ± 3.3 | 6.5 ± 3.6 | 0.32 | 0.92 | 0.80 |
| Fish/shellfish (g) | 84 ± 67 | 84 ± 82 | 1.00 | 104 ± 183 | 73 ± 79 | 0.03 | 0.18 | 0.33 |
| Egg (g) | 42 ± 26 | 31 ± 20 | <0.01 | 33 ± 22 | 28 ± 18 | 0.02 | <0.01 | 0.30 |
| Serum 25(OH)D (ng/ml) | 28.0 ± 5.1 | 26.3 ± 4.4 | 0.03 | 22.9 ± 7.2 | 19.4 ± 6.0 | <0.01 | <0.01 | <0.01 |
| Vitamin D deficiency (25(OH)D <20 ng/ml, %) | 9.0 | 9.8 | 0.86 | 35.4 | 62.2 | <0.01 | <0.01 | <0.01 |
| Vitamin D insufficiency (25(OH)D <30 ng/ml, %) | 62.0 | 82.0 | <0.01 | 85.4 | 94.2 | <0.01 | <0.01 | <0.01 |
Abbreviation: 25(OH)D, 25-hydroxyvitamin D.
aP value for the difference between men and women in each workplace. The independent t-test was used for continuous variables, and the chi-square test was used for categorical variables.
bP value for the difference between workplace A and B in each sex. The independent t-test was used for continuous variables, and the chi-square test was used for categorical variables.