Cross-country variability in Mediterranean lifestyle adherence and its psychosocial and behavioural correlates: insights from the MEDIET4ALL project across 10 Mediterranean and neighboring countries

$\textbf{Background:}$ The Mediterranean lifestyle is increasingly recognized as a multidimensional determinant of health. However, cross-country comparisons using harmonized instruments remain limited. This study aimed to provide a comprehensive country-by-country comparison of Mediterranean lifestyle adherence and associated psychosocial and lifestyle correlates across 10 Mediterranean and neighboring countries participating in the MEDIET4ALL project.
$\textbf{Methods:}$ Cross-sectional data were collected from 4,010 participants (age: 37.2 ± 15.4 years; 59.5% female) using the multinational MEDIET4ALL e-survey. Mediterranean lifestyle adherence was assessed using the MedLife Index and its three domains. Psychosocial status, sleep characteristics, physical activity, sedentary behaviour, social participation, and technology use were evaluated using validated instruments.
$\textbf{Results:}$ Significant cross-country differences were observed in global MedLife adherence and across all domains (p < 0.001, η$^2$ = 0.07–0.11), as well as in the distribution of adherence categories across countries (χ$^2$ = 113.936, p < 0.001). Spain consistently showed higher MedLife scores than several countries (z = 3.42–8.12, adjusted p < 0.001–0.02) and tended to display higher proportions of participants in the high-adherence category, whereas lower adherence was observed in multiple non-Mediterranean and North African contexts. ... mehrPsychological distress differed significantly between countries (p < 0.001), with several contexts showing elevated depression, anxiety, or stress levels (z ≈ 3.57–14.29, adjusted p < 0.001–0.05). Life satisfaction and social participation also varied substantially (194.86, p < 0.001), with some European countries reporting lower social participation compared with Mediterranean and neighboring contexts (z = 3.79–9.31, adjusted p < 0.001–0.05). Sleep parameters and insomnia severity differed markedly across countries (H = 66.64–198.63, p < 0.001), with less favourable sleep profiles observed in several contexts (z ≈ 3.28–12.82, adjusted p < 0.001–0.05). Physical activity and sedentary behaviour showed pronounced variability (p < 0.001), with Jordan reporting the lowest physical activity levels and Tunisia lower sedentary time.
$\textbf{Conclusion:}$ Mediterranean lifestyle adherence and its psychosocial and behavioural correlates vary substantially across countries, reflecting distinct constellations of sociocultural, socioeconomic, and lifestyle factors rather than dietary patterns alone. These findings highlight the importance of multidimensional, context-sensitive approaches to Mediterranean lifestyle promotion and provide a descriptive framework to inform tailored public-health strategies and future longitudinal and intervention research.