[Cross-sectional association between social isolation and nutritional status among older urban adults: The Itabashi Longitudinal Study on Aging].

Aim: The social isolation of older Japanese adults with infrequent contact with others diminishes appetite, reduces food intake, and worsens their nutritional status. However, there is insufficient evidence regarding the association between social isolation and nutritional status, with studies primarily confined to rural and suburban areas. This cross-sectional study aimed to investigate the association between social isolation and nutritional status among older adults residing in urban areas.

Methods: This cross-sectional analysis included 1,052 adults (mean age, 78 years). Nutritional status was assessed using the Mini Nutritional Assessment^® Short Form, with a score of 11 or below indicating malnutrition. Applying the abbreviated Lubben Social Network Scale, a score < 12 was considered indicative of social isolation. Logistic regression was applied to the entire population, then the population was separated by sex, with social isolation as the independent variable and malnutrition as the dependent variable. The covariates included age, living alone, economic status, health, daily activities, smoking habits, drinking habits, and years of education.

Results: Social isolation was observed in 41.7% (n = 439) of the total population, while malnutrition was observed in 27.4% (n = 288). Social isolation was significantly associated with malnutrition (odds ratio: 1.41, 95% confidence interval: 1.06-1.88). Sex subgroup analyses revealed that a significant association was retained only among female participants.

Conclusions: Social isolation has been associated with malnutrition among older urban adults in Japan. Future longitudinal studies of the nutritional status of socially isolated individuals are essential.