Serum Vitamin D, A, and E Concentrations and Their Associations with Chronic Diseases in Adult Patients Referred to Italian General Practitioners’ Offices

Background: Vitamin deficiencies remain prevalent worldwide and contribute to chronic disease burden. This study evaluated serum concentrations of vitamins D, A, and E in Italian general practice populations and examined their associations with prevalent chronic diseases. Methods: This multicenter cross-sectional study enrolled 500 adult patients (median age: 60.7 years; 40.4% male) attending 21 general practice offices across Italy between January 2021 and December 2024. Serum concentrations of 25-hydroxyvitamin D [25(OH)D], vitamin A, and vitamin E were measured alongside demographic, clinical, and biochemical parameters. Statistical analyses included chi-square tests, correlation analyses, and stepwise logistic regression. Results: The median 25(OH)D concentration was 20.4 ng/mL, below optimal levels. Vitamin D deficiency was significantly associated with osteoporosis (p = 0.015), arterial hypertension (p = 0.047), and coronary artery disease (p = 0.002). The median vitamin A (654 μg/L) and vitamin E (11.3 mg/L) concentrations were within normal ranges. Notably, elevated vitamin A levels were significantly associated with arterial hypertension (p = 0.005), diabetes mellitus (p = 0.036), and cancer (p = 0.010). In the multivariate analysis, elevated vitamin A levels emerged as an independent predictor of multiple comorbidities (p < 0.001) and cancer presence (p = 0.014), alongside age, male gender, and body mass index. Conclusions: Vitamin D insufficiency is highly prevalent in Italian primary care populations. Vitamin A concentrations show independent associations with multimorbidity and cancer, suggesting a potential negative influence of an animal-based diet, warranting prospective investigation. These findings highlight the importance of comprehensive vitamin assessment in general practice settings.