The influence of the type of rice served at school lunches on COVID-19 infection in kindergartens and nursery schools

Abstract

Purpose: The purpose of this study was to investigate the effect of processed brown rice on COVID-19 infections by examining whether the number of COVID-19 cases in preschools in 2021 differed depending on whether one type of processed brown rice (sub-aleurone layer residual rinse-free rice: SARFR), or white polished rice, was used as the source of the cases. This study aimed to investigate the effect of processed brown rice on COVID-19 infections. Methods: We investigated the number of COVID-19 cases among preschool infants from April 2021 to March 2022 in kindergartens and nursery schools whose nutritional value of facilities was calculated based on the Dietary Reference Intakes for Japanese by the Ministry of Health, Labor and Welfare. The survey was conducted in the same area within a 3-km linear distance radius, followed by additional surveys of preschools in neighboring areas within a 10-km linear distance radius. Furthermore, we compared the COVID-19 incidence rate with that of Tokyo, where the participating preschools are located. Results: Among preschool infants in the same area, those who received processed brown rice for lunch had a significantly lower percentage of COVID-19 cases than those who received white polished rice. In the neighboring areas, the proportion of affected individuals was also significantly lower in the group consuming processed brown rice. Furthermore, compared to the incidence rate in Tokyo, the incidence rate in the kindergartens where the processed brown rice was consumed tended to be lower. Conclusion: There was a trend toward a lower proportion of COVID-19 infections affected by preschool infants consuming processed brown rice. In the future, it is necessary to examine the preventive effect of consuming processed brown rice not only on COVID-19 but also on other infectious diseases, as well as its mechanism.