A Cross-Sectional Study of Nutrition Knowledge, Diet Quality, Lifestyle, and Health Profiles Among Older Adults Attending Universities of the Third Age in Poland

Background: Population ageing increases the burden of chronic diseases, multimorbidity, and functional limitations, making nutrition and lifestyle important modifiable determinants of healthy ageing. Universities of the Third Age (U3A) provide an educational and social environment for older adults, but multidimensional relationships between nutrition knowledge, diet quality, lifestyle, and health status in this population remain insufficiently characterized. This study aimed to assess these associations among older adults attending U3A in Poland. Methodology: A cross-sectional online survey was conducted between January and April 2026 among community-dwelling older adults participating in U3A programs. Of 700 distributed invitations and 520 returned questionnaires, 450 complete and eligible responses were included. The questionnaire was based on the KomPAN® framework and expanded with items on health, lifestyle, psychosocial resources, barriers to healthy eating, and sources of health information. Diet quality was assessed using the pro-Healthy Diet Index, non-Healthy Diet Index, and overall Diet Quality Index (DQI). Nutrition knowledge was measured using a 24-item scale. Analyses included distributional diagnostics, non-parametric group comparisons, FDR-corrected Spearman correlations, psychometric assessment, principal component analysis, multivariable regression with model diagnostics, and profile segmentation. Results: The mean age was 73.63 ± 5.73 years, and most participants were women. The median DQI was 15.59 [3.93–24.86], with a predominance of neutral diet quality. Nutrition knowledge was moderate, with a median score of 12.00 [9.00–15.00], and the scale showed very good internal consistency. PCA identified three dietary patterns: convenience/ultra-processed, prudent/health-promoting, and traditional meat-and-fat. Higher DQI was associated with better nutrition knowledge, greater physical activity, a more favorable sleep profile, regular meal timing, and lower disease burden. Participants with multimorbidity had significantly lower DQI. Segmentation distinguished a health-engaged/higher-resource profile and a lower-resource/nutritionally vulnerable profile. Conclusions: U3A participants in Poland are educationally and socially active but nutritionally heterogeneous. The predominance of neutral diet quality, moderate nutrition knowledge, and identifiable knowledge gaps indicates the need for targeted, practical, and behavior-oriented nutrition education supporting healthy ageing.