Interaction of Eating Status and Dietary Variety on Incident Functional Disability among Older Japanese Adults

OBJECTIVES: To examine whether eating status and dietary variety were associated with functional disability during a 5-year follow-up analysis of older adults living in a Japanese metropolitan area. DESIGN: A 5-year follow-up study. SETTING: Ota City, Tokyo, Japan. PARTICIPANTS: A total of 10,308 community-dwelling non-disabled adults aged 65–84 years. MEASUREMENTS: Eating status was assessed using a self-reported questionnaire. Dietary variety was assessed using the dietary variety score (DVS). Based on the responses, participants were classified according to eating alone or together and DVS categories (low: 0–3; high: 4–10). Functional disability incidence was prospectively identified using the long-term care insurance system’s nationally unified database. Multilevel survival analyses calculated the adjusted hazard ratio (HR) and 95% confidence interval (CI) for incident functional disability. RESULTS: During a 5-year follow-up, 1,991 (19.3%) individuals had functional disabilities. Eating status or DVS were not independently associated with incident functional disability. However, interaction terms between eating status and DVS were associated with functional disability; HR (95% CI) for eating together and low DVS was 1.00 (0.90–1.11), eating alone and high DVS was 0.95 (0.77–1.17), and eating alone and low DVS was 1.20 (1.02–1.42), compared to those with eating together and high DVS. CONCLUSION: Older adults should avoid eating alone or increase dietary variety to prevent functional disability. This can be ensured by providing an environment of eating together or food provision services for eating a variety of foods in the community. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material is available for this article at 10.1007/s12603-022-1817-5 and is accessible for authorized users.