Prevalence and non-invasive predictive models of vitamin D insufficiency in Paraguayan youth: the role of body composition and traditional mate consumption

Background Vitamin D (VD) insufficiency among youth remains a latent public health concern in Paraguay, and non-invasive, population-specific screening tools are unestablished. This study aimed to identify clinical, body composition, and lifestyle predictors to develop a preliminary, non-invasive risk scoring system for Paraguayan youth. Methods Serum 25-hydroxyvitamin D levels, bioelectrical impedance-derived body composition, and lifestyle habits were evaluated in 164 participants (aged 17–35 years) at the Universidad Santa Clara de Asís. Multivariable logistic regression models were constructed after resolving multicollinearity (variance inflation factor <1.40) and underwent internal validation via 1,000 bootstrap resamples. Results The overall prevalence of VD insufficiency (<30 ng/mL) was 48.2%. Multivariable analysis revealed an independent contribution of sex-specific muscle mass deviations (Δ Muscle Mass), showing decreased VD levels in both the sarcopenic obesity phenotype and high muscle-low fat athletic phenotype, supporting the skeletal muscle tissue reservoir hypothesis. Among lifestyle factors, full-coverage clothing was an independent risk factor, whereas vigorous physical activity and habitual mate/tereré consumption (≥4 days/week) were significant associated with a lower probability of VD insufficiency. The global predictive scorecard achieved an optimism-corrected area under the receiver operating characteristic curve (optimism-corrected AUC) of 0.714. Crucially, the subgroup model restricted to overweight individuals (BMI ≥ 25 kg/m 2 ) demonstrated acceptable exploratory discrimination (optimism-corrected AUC = 0.768, sensitivity 69.2%, specificity 89.7%), serving as a preliminary proof-of-concept assessment for risk stratification. Conclusion By integrating body composition dynamics and cultural habits, this cost-effective model provides a preliminary, exploratory non-invasive screening structure for Paraguayan youth that warrants further multi-center prospective validation before clinical implementation.