Correlation between Tryptophan Daily Intake and Occupational Factors with Stress Outcome Scores among Offshore and Onshore Workers

Abstract

Introduction. Offshore and onshore workers have a higher risk of psychological stress related to their job. Stress reactions vary depending on the type of stressor, the duration or severity of the stressor, their genetics, their coping styles, and their nutrition. Tryptophan is an essential amino acid precursor of serotonin and melatonin, which have an antidepressant effect and roles in stress perception and management. This study assessed the correlation of daily tryptophan intake and occupational factors with stress outcome scores based on the Indonesian Short Version New Brief Job Stress Questionnaire (SV-NBJSQ) among offshore and onshore workers.

Methods. A cross-sectional study was conducted on 14 offshore workers and 20 onshore workers. Interviews and questionnaires were conducted to obtain demographic data, dietary intake, occupational factors, and stress outcome scores. Tryptophan daily intake was measured through a single 24-hour dietary recall and a one-day-weighted food record. Data of average daily intake for two days were analyzed using the NutriSurvey software based on the food composition table from The United States Department of Agriculture National Nutrient Database for calculating tryptophan intake.

Results. The median (min-max) tryptophan daily intake of offshore workers was 5.5 (1.9–9.9) mg/kg, and 4.5 (1.4–7.5) mg/kg among onshore workers. There was no difference in tryptophan daily intake between offshore and onshore workers (p = 0.064). There was no significant difference between occupational factors except for the shorter tenure of offshore workers (12.5 vs 3, p < 0.001). There was no significant correlation between tryptophan daily intake and each of the stress outcome scores. There was a significant correlation between occupational factors and stress outcome scores among offshore and onshore workers, specifically between workload and fatigue (r = 0.35, p =0.04), workload and depression (r = 0.4, p = 0.02), interpersonal conflict and anxiety (r = 0.47, p = 0.005), role conflict and anxiety (r = 0.47, p = 0.005), as well as between tenure and physical reaction stress (r = -0.42, p = 0.02).

Conclusion. Adequate tryptophan daily intake and high stress outcome scores among offshore and onshore oil
and gas workers are observed in this study, and no correlation was found between the two. Similar food sources, homogeneous occupational stressors, the selection bias of the “healthy worker effect” or other factors that were not studied may influence the findings. There is a correlation between occupational factors and stress outcome scores, namely workload and fatigue, workload and depression, interpersonal conflict and anxiety, role conflict and anxiety, and tenure and stress physical reactions.