Weekly Working Hours and Serum Vitamin D 3 Levels Among Korean Wage Workers : Evidence From KNHANES 2022-2023.

OBJECTIVE

To examine whether weekly working hours are associated with serum vitamin D levels among Korean wage workers.

METHODS

This cross-sectional study used data from 2988 adults in the 2022-2023 Korea National Health and Nutrition Examination Survey. Serum 25(OH)D 2 and 25(OH)D 3 were measured by liquid chromatography-mass spectrometry. Associations with weekly working hours were analyzed using multivariable linear regression, adjusting for age, sex, education, and occupation.

RESULTS

Each additional weekly working hour was associated with a 0.057-ng/mL decrease in 25(OH)D 3 levels, with no significant association for 25(OH)D 2 . The inverse association was stronger among white-collar, highly educated, and obese workers.

CONCLUSIONS

Long working hours are significantly linked to lower serum vitamin D 3 levels. These findings highlight working hours as a modifiable occupational determinant of vitamin D deficiency, particularly in indoor or white-collar settings.