Relationship between Frequency of Meals Comprising Staple Grain, Main, and Side Dishes and Nutritional Adequacy in Japanese Adults: A Cross-Sectional Study.

Meals comprising a staple grain, a main, and side dishes (SMS meals) promote good dietary intake, yet limited studies have examined their multifactorial relationship with dietary intake. We investigated how demographic characteristics, lifestyle, and dietary habits affect the relationship between SMS meal frequency and nutrient intake adequacy. This cross-sectional study analyzed survey data from 331 Japanese adults (208 men and 123 women) aged 30-69 years in February 2019. SMS meal frequency was evaluated according to respondents' answers to how many days a week they consumed ≥2 daily SMS meals. Dietary intake was evaluated using the brief self-administered diet history questionnaire. Differences in nutrient intake adequacy among groups according to SMS meal frequency were determined using multiple logistic regression. Less frequent SMS meals correlated with a lower intake of protein, water-soluble vitamins, and certain minerals, with more individuals falling below the estimated average requirement for nutrient intake. However, no relationship was found between SMS meal frequency and nutrient intake concerning tentative dietary goals for preventing lifestyle-related diseases. Our findings indicate that adopting SMS meals could achieve adequate intake of some nutrients and enhance overall diet quality among Japanese adults.