Decline of instrumental activities of daily living is a risk factor for nutritional deterioration in older adults: a prospective cohort study

BACKGROUND: The association between functional capacity and the subsequent risk of nutritional deterioration is yet to be understood. The purpose of this study was to elucidate the relationship between functional capacity, comprising instrumental activities of daily living (IADL), intellectual activity, and social function, and future decline in nutritional status. METHODS: The current study is a two-year prospective cohort study. A total of 468 community-dwelling older adults without nutritional risks were enrolled. We used the Mini Nutritional Assessment Screening Form. Functional capacity, including IADL, intellectual activity, and social function, was assessed using the Tokyo Metropolitan Institute of Gerontology Index of Competence at baseline. The nutritional status was reassessed at a 2-year follow-up. Risk ratios (RR) of functional capacity for the incidence of nutritional decline were estimated. RESULTS: Low functional capacity was significantly associated with future deterioration of nutritional status (RR 1.12, 95% confidence interval [CI] 1.02–1.25). Of the subdomains of functional capacity, IADL decline (adjusted RR 2.21, 95% CI 1.18–4.13) was an independent risk factor for the incidence of nutritional risk. Intellectual and social activities were not significant. CONCLUSION: Decline in functional capacity, especially IADL, is a risk factor for future deterioration in nutritional status. Further studies are required to elucidate the effect of interventions for IADL decline on maintaining nutritional status in older adults. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12877-023-04185-6.