Abstract
Previous our investigation has suggested that Japanese diet is associated with mental health and specified that rice, miso (soybean paste) and fish consumption affected to quality of life, sleep quality, impulsiveness and depressiveness. Furthermore, the study showed combination of rice and miso was supposed to be associated to mental and physical health. The Japanese diet consists of rice and other dishes with vegetable, fish and meat. Combinations of rice and other dishes have been developed over the centuries in order to have nutritionally balanced diet. We hypothesized rice-based diet impacts mental and physical health and investigate the consequences of dietary intervention of rice.
The study is a randomized, open trial, parallel-groups clinical trial where 60 participants were screened with inclusion criteria, which is (1) eating regularly 3 meals per day and (2) eating staple foods other than rice one or more times. Participants were randomly assigned to have rice-based meals or no rice-centered meals for 3 dairy meals for 2 months. Participants were surveyed sleep quality, quality of life, anxiety scale and dietary pattern before and after the experimental period. As well as questionnaire surveys, biochemical changes focusing on orexin A, cortisol and eotaxin-1 were measured in the blood.
The sleep quality index scores showed improvement after the intervention of rice-based meal. In addition to the subjective assessment, blood plasma eotaxin-1 levels substantially reduced by the intervention. Several molecular studies demonstrated that eotaxin-1 impaired neurogenesis, synaptic plasticity and cognition, thus the molecule is suggested negative modifier of central nervous system. Although the relationship between sleep quality and blood plasma eotaxin-1 level has not been cleared so far, findings of the present study support that rice-based diet benefits brain health.