Effect of Cereal Consumption (Frugra<sup>®</sup>) on Autonomic Nervous System Function in Healthcare Workers Who Skip Breakfast

In this study, we aimed to clarify the effects of breakfast intervention on autonomic nerve function in healthcare workers who skip breakfast. This cross-sectional, interventional study was conducted between January 2020 and December 2021. All participants were full-time healthcare workers who completed a self-administered questionnaire on fatigue and subjective symptoms and underwent noninvasive autonomic nerve function tests. "Skippers" were defined as individuals who ate breakfast <4 times per week, and "eaters" were those who ate breakfast >4 times per week. We introduced a cereal, Frugra (Calbee, Inc.), to skippers who opted for the breakfast intervention. Subsequently, they completed the questionnaire again and repeated the autonomic nerve function tests. Among 196 participants (age [mean±SD]: 29.8±7.8 y; 177 women and 19 men), 120 were categorized as skippers and 76 as eaters. In the skipper group, more participants were nurses, lived alone, and worked the night shift than in the eater group. The Chalder Fatigue Scale (CFS) score in the skipper group was higher than that in the eater group, although not significantly. Regarding autonomic nerve function, no significant differences were observed between the groups. In 50 skippers who opted for the breakfast intervention, the CFS score significantly decreased after 4 wk. Log low frequency and log coefficient of component variance total power significantly increased, whereas log high frequency increased, but not significantly, after the intervention. In conclusion, for healthcare workers who were breakfast skippers, the consumption of breakfast cereal reduced their fatigue level and improved their autonomic nervous system activity.