Association of Estimated 24-h Urinary Na/K Ratio with Dietary Salt and Vegetables Intake in male Japanese Transport Drivers

Abstract

Objective: The associations of the estimated 24-h urinary sodium-to-potassium (24-u-Na/K) ratio with dietary salt and vegetable intake was examined in male Japanese transport drivers. This study aimed to identify factors specific to this occupation for hypertension prevention and health guidance.

Methods: A cross-sectional study enrolled 492 male Japanese drivers (aged 22–70 years) of a transport company in Ishikawa Prefecture. The 24-u-Na/K ratio was estimated from a formula using collected spot urine. A self-administered questionnaire was used to assess a salt check sheet, daily vegetable intake, and health-related behaviors during health examinations in the summer of 2020. The participants were grouped into four according to the interquartile range of the 24-u-Na/K ratio: group I, <3.25; group II, ≥3.25 to <3.78; group III, ≥3.78 to <4.41; and group IV, ≥4.41.

Results: Of the participants, 65.2% had high blood pressure. The average estimated 24-h salt intake was 9.7 ± 2.2 g/day, and the median total score for the salt check sheet was 13.0 points, and both were highest in group IV. The median daily vegetable intake was 2.2 dishes, and no significant differences were found among the groups. The lowest intake was in the order of dinner, lunch, and breakfast.

Conclusion: The high rate of hypertension among transport drivers suggests the need for the provision of dietary support to reduce salt intake and increase vegetable intake in this population and not just in those with a high 24-u-Na/K ratio.