title: Dietary quality and its structural relationships among equivalent income, emotional well-being, and a five-year subjective health in Japanese middle-aged urban dwellers.
abstract: BACKGROUND
  Although dietary quality in middle-age and the prime age of a person's work career might be determined by positive emotional well-being based on socioeconomic status (SES), causation among determinants of dietary quality still remains unclear. Our purpose was to elucidate the structural relationships among five-year prior dietary quality, equivalent income, emotional well-being, and a five-year subjective health by sex and age group separately.
  
  
  METHODS
  In 2003, 10,000 middle-aged urban dwellers aged 40-64 years, who lived in ward A in the Tokyo metropolitan area, were randomly selected and a questionnaire survey was conducted by mail. In 2008, we made a follow-up survey for dwellers, and were able to gather their survival status. A total of 2507, middle-aged men (n = 1112) and women (n = 1395), were examined at baseline. We created three latent variables for a structural equation modeling (SEM), five-year subjective health reported in 2003 and in 2008, dietary quality of principle food groups diversity and eating behavior in 2003, and emotional well-being constructed by enjoyment & ikigai (meaning of life) and by close people in 2003. Equivalent income in 2003 was calculated as SES indicator.
  
  
  RESULTS
  In the SEM analysis of both men and women, there was an indirect effect of the equivalent income on dietary quality and on five-year subjective health, via emotional well-being explained by ikigai and having comforting people close to the individuals, significantly. There tended to be a larger direct effect of emotional well-being on the dietary quality in men than in women, and also a larger effect accompanying with aging. In women, there was a large direct effect of equivalent income on dietary quality than in men. When examined comprehensively, there appeared to be a larger effect of five-year prior equivalent income on subjective health during five-year in men than in women.
  
  
  CONCLUSIONS
  This study suggests that it is necessary to support the improvement of dietary quality in middle age by considering the characteristics of sex and age group and also by providing supportive environment to enhance emotional well-being based on equivalent income, cooperating different field professionals to provide such as employment or community support program.
authors.affiliation: Department of Health and Nutrition, School of Human Ecology, Wayo Women's University, Chiba, Japan.
authors.forename: Sayuri
authors.initials: S
authors.lastname: Kodama
authors.affiliation: Graduate School of Urban System Science, Tokyo Metropolitan University, Tokyo, Japan.
authors.forename: Nobuya
authors.initials: N
authors.lastname: Fujii
authors.affiliation: Department of Health and Nutrition, School of Human Ecology, Wayo Women's University, Chiba, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Furuhata
authors.affiliation: Graduate School of Medicine, The Jikei University, Tokyo, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Sakurai
authors.affiliation: Tokyo Metropolitan Institute of Gerontology, Tokyo, Japan.
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Fujiwara
authors.affiliation: Graduate School of Urban System Science, Tokyo Metropolitan University, Tokyo, Japan.
authors.forename: Tanji
authors.initials: T
authors.lastname: Hoshi
keywords: Dietary quality; Emotional well-being; Equivalent income; Middle-age; Subjective health