Effect of dried-bonito broth (Katsuo-bushi dashi) on mental fatigue and stress caused by simple workload and task performance

Abstract

The effect of dried-bonito broth on the mental fatigue and stress caused by simple workload and task performance is investigated. After a 1-week non-ingestion period, female subjects (n = 31, 20.5±0.6 years old) ingested driedbonito broth (dry matter, 4.9 g) daily for 1 week. The evaluation was performed after the non-ingestion and ingestion periods. For the simple workload, the Uchida-Kraepelin psychodiagnostic test (UKP) was administered. Profiles of Mood States (POMS) scores, flicker values and salivary cortisol were measured before and after UKP loading. After the non-ingestion period, post-loading flicker values were significantly lower than the pre-loading values, while there were no significant changes after the ingestion period. Pre-loading salivary cortisol concentrations significantly decreased during the ingestion period. Furthermore, UKP error rates after the ingestion period were significantly lower than after non-ingestion period. The results suggest that daily ingestion of dried-bonito broth for 1 week tends to lower the accumulation of mental fatigue and stress responses, and tends to suppress the lowering of task performance in a simple workload test.