The effects of social frailty on diet and nutrition are under-investigated. Our study aimed to assess the association between social frailty and diet quality, diet quantity, and nutrition over a 3-year period in community-dwelling older Japanese adults. This prospective cohort study recruited individuals aged ≥60 years from a community college and followed up 666 participants annually. Social frailty was determined using a 4-item questionnaire. Diet quantity (energy and macronutrient intake) and diet quality (dietary diversity score and Diet Quality Index-International) were assessed using a food frequency questionnaire. Nutrition was evaluated using the Mini-Nutritional Assessment (MNA). Out of the 666 participants (56.5% women), 250 (37.5%) were categorized as having social prefrailty or frailty. Regarding diet quantity, energy intake (β = -1.59kcal/kg/day, p < 0.01) and nutrient intake (protein intake, β = -0.08g/kg/day; fat intake, β = -0.06g/kg/day; carbohydrate intake, β = -0.18g/kg/day; fiber intake, β = -0.01g/kg/day; all p < 0.05) were lower in men with social prefrailty or frailty than in men with social robustness. Dietary diversity score (β = -0.25, p = 0.01) and MNA score (β = -0.32, p = 0.04) decreased in men with social prefrailty or frailty. However, these associations were not observed in women. Social frailty is associated with lower dietary intake, poor diet quality, and poor nutrition among community-dwelling older men. Future studies are required to determine the benefits of sex-specific interventions targeting social frailty on nutritional outcomes.
Keywords: diet quality; diet quantity; nutritional status; sex difference; social frailty.