The aim was to examine the association between social frailty and diet quality in adults over 65 years of age, and whether results differed by sex.

Population-based cross-sectional study using data from the Spanish National Health Survey.

5,071 community-dwelling people ≥65 years from Spain.

Social frailty was deemed to exist when the person both lived alone and had low social support, measured with the Duke-UNC scale. Diet was assessed with the Spanish Healthy Eating Index (S-HEI), ranging from 0 to 100 points (highest diet quality). Means and 95% confidence intervals of the S-HEI score for each social frailty group were calculated using linear regressions, with socially robust people as reference. Analyses were adjusted for main confounders, including sociodemographic, lifestyle and morbidity variables.

There were no differences in the S-HEI adjusted mean of socially frail (74.3 points, 95%CI: 73.4−75.2) compared to socially robust older adults (75.4 points; 95%CI: 75.1−75.7). In sex-stratified analyses, the S-HEI adjusted mean of socially frail men (71.9 points; 95%CI: 70.6−73.2) was lower than robust men (74.8 points; 95%CI: 74.4−75.3). Specifically, social frailty was associated with lower consumption of vegetables, fruits, dairy and lower diet variety in men. Differences were not observed according to social frailty among older women.

Social frailty was associated with poor diet quality in community-dwelling older men, but not in women in Spain. Gender differences in self-care could partly explain this association. Sex-specific interventions are required to minimize the impact of social frailty on diet quality.