Coffee consumption and psychological wellbeing among Japanese auto factory workers.
Tomoyuki Kawada
PMID 34366307WHAT IT FOUND
Coffee consumption was not significantly associated with poor psychological wellbeing in male Japanese factory workers.
Regular exercise and longer sleep were protective factors, particularly for older workers aged 45–60 years.
Key findings
01After adjusting for age, smoking, exercise, and sleep, coffee consumption showed no significant association with poor psychological wellbeing.
02Regular exercise and longer sleeping time were protective against poor psychological wellbeing, with stronger effects in workers aged 45–60 years.
03Workers drinking more than 2 cups per day had a significantly higher prevalence of poor psychological wellbeing compared to those drinking less than 1 cup per week.
STILL TO COME
How it was doneWhat they foundWhat it means for PTsWhat it means for OTs
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What it does not show
The study only included male workers, so results cannot be generalized to women. The cross-sectional design cannot establish causality. Participants were restricted to ages 35–60, excluding older and younger workers. The specific job roles (e.g., management vs. manufacturing) were not differentiated. A healthy worker effect may bias the results.
Declared interests
The authors declared no conflicts of interest. The study was approved by the Ethics Committee, and responses were kept confidential from company management.
The easy way to misread this
Do not conclude that high coffee consumption causes poor psychological wellbeing. While workers drinking >2 cups/day had a higher prevalence of poor wellbeing, this association disappeared after adjusting for smoking, exercise, and sleep, indicating these lifestyle factors are more relevant.