Effect of dried-bonito broth on mental fatigue and mental task performance in subjects with a high fatigue score

Abstract

Dried-bonito broth is commonly employed as a soup and sauce base in Japanese cuisine and is considered to be a nutritional supplement that promotes recovery from fatigue. Previous human trials suggest that the ingestion of dried-bonito broth improves several mood states; however, its effect on fatigue has not yet been clarified. The aim of this study was to clarify the effects of daily ingestion of dried-bonito broth on fatigue and cognitive parameters by a placebo-controlled double blind crossover trial. Forty-eight subjects with fatigue symptoms ingested the dried-bonito broth or a placebo solution every day for 4 weeks. Mood states were evaluated by the Profile of Mood States (POMS), and mental task performance was evaluated by the Uchida–Kraepelin psychodiagnostic (UKP) test. Fatigue and total mood disturbance (TMD) scores on the POMS test decreased significantly during the dried-bonito broth ingestion ( p < 0.05), but did not change significantly during placebo ingestion. The change in vigor score during dried-bonito broth ingestion was significantly higher than that during placebo ingestion at 2 weeks ( p < 0.05). The results of the UKP test indicate that the numbers of both total answers and correct answers significantly increased during dried-bonito broth ingestion ( p < 0.05), while no significant changes were observed in the placebo ingestion. These results suggest that the daily ingestion of dried-bonito broth may improve the mood states, may reduce mental fatigue and may increase performance on a simple calculation task.