Association of dietary diversity measured by the number of dishes with cardiovascular risk factors among Japanese adults: findings from the National Health and Nutrition Survey, 2018-19

BACKGROUND: The Japanese-style diet has attracted attention as a factor contributing to the Japanese population's longevity by reducing cardiovascular disease (CVD) mortality. The Japanese-style diet is said to be "ichijusansai" (rice with one soup and three dishes) and is characterized by a high number of dishes. However, the relationship between the number of dishes in all meals (NDAM) and CVD risk factors remains unclear. METHODS: In this cross-sectional study, we analyzed data from 2,900 participants aged ≥20 years from the 2018-19 National Health and Nutrition Survey. Participants were divided into four groups according to sex and NDAM. NDAM was calculated based on a one-day weighed dietary record, excluding beverages, and including all other dishes and foods. Multivariable relative risks (RRs) were estimated using a modified Poisson regression model adjusted for age, living alone, area, occupation, exercise habits, smoking habits, drinking habits, and total energy intake. RESULTS: Participants with higher NDAM were more likely to be older, non-smokers, and physically active. In men, higher NDAM (Groups 2-4) was associated with a lower risk of dyslipidemia compared to Group 1 (the lowest NDAM). In women, an inverse association was observed for overweight/obesity, with Group 4 (the highest NDAM) showing a lower risk than Group 1. Furthermore, a lower risk of hypertension was found in Groups 2-3 compared to Group 1. However, these associations did not remain statistically significant after Bonferroni correction. CONCLUSION: A diet with a high NDAM may be inversely associated with several CVD risk factors among Japanese adults.