Search Results (3,158)

Background/Objectives: Vitamin D has been implicated in lipid metabolism, but data regarding its association with atherogenic lipoproteins in elite athletes remain limited. Elite athletes represent a unique research model to investigate these associations with reduced confounding from obesity, chronic disease, smoking, and physical inactivity. Methods: This cross-sectional study included 773 male professional athletes from mixed sports disciplines (mean age 25.5 ± 5.0 years). Serum 25-hydroxyvitamin D [25(OH)D] concentrations and lipid parameters, including total cholesterol, low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), triglycerides, and lipoprotein(a) [Lp(a)], were assessed. Associations were analyzed using correlation analyses, subgroup comparisons according to predefined 25(OH)D categories (<30, 30–50, and >50 ng/mL), and multivariable linear regression models adjusted for age, body mass index, season, and training-related variables. Results: Higher serum 25(OH)D concentrations were independently associated with lower LDL-C (p = 0.028), triglyceride (p = 0.002), and Lp(a) concentrations (p = 0.036), whereas no independent association was observed with HDL-C (p = 0.559). Athletes with 25(OH)D concentrations ≥30 ng/mL demonstrated lower LDL-C, triglyceride, and Lp(a) levels compared with athletes below this threshold (all p < 0.05). Higher vitamin D status was additionally associated with greater peak exercise performance (4.29 ± 1.15 vs. 3.36 ± 0.68 W/kg; p < 0.001). Conclusions: Higher 25(OH)D concentrations were independently associated with a more favorable lipid profile in elite athletes, including lower LDL-C, triglyceride, and Lp(a) concentrations. Prospective studies are warranted to further investigate the relationship between vitamin D status and lipid metabolism in athletic populations. Full article

Background: Type 2 diabetes mellitus (T2DM) is a global health challenge characterized by chronic hyperglycemia and oxidative stress. Pithecellobium dulce root has long been recognized for its antidiabetic potential; however, its specific bioactive constituents and mechanisms of action remain poorly defined. This study aimed to evaluate the antidiabetic and antioxidant properties of extracts and isolated molecules from P. dulce root bark. Methods: The DCM/MeOH crude extract of P. dulce root bark was fractionated with n-hexane (PDEH) and ethyl acetate (PDAE), followed by chromatographic purification and spectroscopic characterization, yielding seventeen compounds (1–17). The antioxidant activity (DPPH, ABTS, FRAP) and antidiabetic potential of PDEH, PDAE, and 1–17 were assessed in vitro using yeast-derived enzymes and in silico (targeting human α-glucosidase [PDB: 2QLY] and human α-amylase [PDB: 4GQR]). The in vitro α-glucosidase experiments used saccharomyces cerevisiae enzyme, which varies from the human target. Therefore, these results should be taken as preliminary screening data that needs confirmation with human enzymes. Results: Compound 1 was identified as new, while 2 was isolated for the first time from a natural source. The cell-free chemical tests DPPH, ABTS, and FRAP measured antioxidant capability. These tests quantify radical-scavenging and electron-transfer capabilities in vitro and are preliminary chemical screening methods. They do not directly represent biological antioxidant activity in cells or organisms. PDEH demonstrated strong radical scavenging against DPPH (IC₅₀ = 15.30 μg/mL) and ABTS (IC₅₀ = 12.80 μg/mL), while pristriol (16) showed ferric reducing power (EC₅₀ = 4200 μM FeSO₄/g). Enzyme inhibition assays demonstrated activity against α-amylase (IC₅₀ 53.88–112.24 µg/mL; acarbose IC₅₀ = 91.20 µg/mL) and α-glucosidase (IC₅₀ 18.38–136.88 µg/mL; acarbose IC₅₀ = 11.31 µg/mL). Compounds 15, 1, and 2 showed superior activity compared to acarbose for α-amylase, with effect sizes (Cohen’s d) of 2.15, 0.94, and 0.82, respectively, and IC₅₀ values of 53.88, 88.15, and 92.62 µg/mL; for α-glucosidase, IC₅₀ values were 18.38, 39.25, and 36.40 µg/mL, respectively. Docking studies supported these findings, revealing binding energies of −9.08, −8.34, and −7.22 kcal/mol for compounds 1, 2, and 15 with α-amylase, and −10.35 and −9.79 kcal/mol for compounds 1 and 2 with α-glucosidase. ADME profiling further identified 1 and 2 as promising lead candidates for dual-enzyme inhibition. Conclusions: P. dulce root bark represents a potent source of bioactive molecules with both antioxidant and dual-enzyme-inhibitory properties. These findings validate its traditional use and highlight its potential in the development of multitarget therapies for T2DM management. Full article

This study evaluated the effects of replacing 25% of wheat straw with dried carob (Ceratonia siliqua) leaves and twigs, either untreated or treated with 5% sodium hydroxide (NaOH), on growth performance, nutrient digestibility, carcass traits, meat quality, blood metabolites, and rumen microbial populations in Assaf lambs. Twenty-four male lambs (2.5 months old; 29 ± 0.5 kg) were randomly assigned to three dietary treatments (n = 8): a control diet containing wheat straw as the sole roughage source, supplemented with a concentrate feed, a diet with 25% untreated carob leaves and twigs (UCL), and a diet with 25% NaOH-treated carob leaves and twigs (TCL). Following a 14-day adaptation period, lambs were fed the corresponding experimental diet for 14 weeks. Carob inclusion improved growth performance, with UCL lambs showing the highest average daily gain (214 g/d) compared with TCL (201 g/d) and control (160 g/d), resulting in improved feed conversion ratio (9.02 vs. 5.68 and 5.63, respectively) (p < 0.001). Blood urea nitrogen was reduced (p < 0.001) in UCL lambs (26.8 vs. 38.5 mg/dL in control), suggesting improved nitrogen retention. Digestibility responses differed between treatments (p < 0.001), as TCL increased dry matter digestibility to 72.6% compared with 65.4% (UCL) and 63.6% (control), indicating enhanced nutrient utilization following NaOH treatment. Both UCL and TCL increased (p < 0.001) carcass weights (up to 24.7 vs. 21.0 kg in control), while TCL achieved the highest dressing percentage (46.6% vs. 43.4%). Meat quality traits were generally unaffected in terms of color (lightness, redness, and yellowness) and water-holding capacity; however, shear force decreased from 33.6 N (control) to 30.0 N (TCL), indicating improved tenderness. Carob inclusion modified meat composition by increasing (p < 0.001) lipid content (12.0–12.2 vs. 9.6%) and improving fatty acid profile, with reduced saturated fatty acids (53.4–56.5 vs. 61.4%) and increased α-linolenic acid (2.04 vs. 1.58%), leading to a lower n-6/n-3 ratio (5.54–5.61 vs. 6.45). Rumen fermentation was also affected (p < 0.001), as carob diets increased total bacterial populations and reduced protozoal counts, suggesting shifts toward more efficient microbial activity. In conclusion, replacing 25% of wheat straw with carob leaves improved growth performance and feed efficiency, with untreated carob primarily enhancing nitrogen utilization and treated carob improving fiber digestibility and carcass yield. These findings support the use of carob by-products as a viable alternative feed resource, although responses depend on processing method and targeted production outcomes. Full article

The sluggish kinetics of alkaline hydrogen oxidation reaction (HOR) and high cost of Pt–based catalysts have long hindered large–scale deployment of alkaline membrane fuel cells. Via first–principles calculations, we designed a series of 3d transition metal single atoms anchored on PdN₂ monolayer (TM–PdN₂, TM = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn) and evaluated their alkaline HOR performance. Ti-, Cr-, Fe-, Co-, Ni-modified systems exhibit excellent thermodynamic and electrochemical stability under operating conditions. Single-atom doping tunes the p-band center of N and d-band center of metal sites, enabling precise modulation of H and OH adsorption strengths. Mechanistic analysis reveals HOR follows H₂ + 2OH* → H* + OH* + H₂O → 2H₂O, with the final step as rate-determining step. H adsorption contributes 3.45 times more to HOR activity than OH adsorption. Fe–PdN₂ delivers the best performance, with an ultra–low barrier of 0.11 eV and a rate constant of 2.82 × 10¹⁰ s^–1·site⁻¹, values that significantly outperform those of Pt(111) (0.22 eV, 4.5 × 10⁹ s⁻¹·site⁻¹). This work provides theoretical guidance for rational design of high–performance alkaline HOR electrocatalysts. Full article

Background: Post-thyroxine treatment of thyroid dysfunction remains a clinical concern, especially in Middle Eastern populations. Methods: This descriptive cross-sectional study was conducted in 2023 at King Fahad Hospital, Hufof, Kingdom of Saudi Arabia. Of the 237 patients treated with L-thyroxine (L-T4) for hypothyroidism, 163 patients, almost exclusively females (152 females, 11 males), met the inclusion criteria and were enrolled. Thyroid hormones, lipid profiles, and 25-hydroxyvitamin D (25OH-D) were measured using standard laboratory assays. Results: Only 57% of patients achieved euthyroid status following L-T4 treatment, while 12.3% developed post-thyroxine-treatment (PTT) hyperthyroidism, and 30.7% developed PTT hypothyroidism. Older age was significantly associated with dysthyroidism (p = 0.018), whereas obesity (p = 0.937) and vitamin D levels (p = 0.982) were not. Total cholesterol (TC) and LDLc positively correlated with TSH levels, while elevated triglycerides (TGs) were significantly associated with PTT hyperthyroidism. The two dysthyroid subgroups were comparable across all non-thyroid parameters, including age, BMI, 25(OH)D levels, and lipid fractions. However, free T4 was significantly higher in PTT hyperthyroidism (p < 0.001); free T3 showed a trend toward higher levels in PTT hyperthyroidism (p = 0.052); and TSH was significantly higher in PTT hypothyroidism (p < 0.001). Conclusions: The proportions of patients with PTT hypo- and hyperthyroidism are aligned with international observations. Furthermore, the age was significantly associated with dysthyroidism, and dyslipidemia is the most consistent biochemical correlate of suboptimal thyroid status; however, the associations of PTT dysthyroidism with hypovitaminosis D and BMI were not noticed in this setting. Full article

Background and Objectives: Vitamin D deficiency is a pervasive public health issue in high-latitude regions, yet large-scale population data for the Baltic states remain sparse. This study aimed to determine the prevalence of vitamin D status and identify its primary determinants within a primary care setting in Lithuania. Materials and Methods: We conducted a retrospective cross-sectional analysis of serum 25-hydroxyvitamin D [25(OH)D] concentrations from 14,330 unique patients (aged 1–101 years) collected during 2025 at a major clinic in Vilnius. Vitamin D status was categorized according to the Central and Eastern European Expert Consensus thresholds. Results: The overall median 25(OH)D concentration was 68.3 nmol/L, placing it in the “insufficiency” range (50–75 nmol/L). Seasonality emerged as the most significant predictor of deficiency; multivariable logistic regression showed a maximal risk reduction in September (OR 0.33; 95% CI: 0.27–0.41) and August (OR 0.34) compared to January, while June and November provided no significant protection. Age-specific analysis revealed a non-linear “U-shaped” distribution: children aged 0–6 years had the highest levels (median ~87–91 nmol/L), likely due to rickets prophylaxis, whereas adolescents (12–18 years) exhibited the highest vulnerability, with approximately 80% suffering from deficiency or insufficiency. Males faced a 13.9% higher likelihood of deficiency than females (OR 1.14; p = 0.0036), potentially due to lower rates of elective supplementation. Conclusions: These findings suggest that current supplementation strategies successfully protect infants but fail to sustain adequacy through adolescence and adulthood, particularly during the “vitamin D winter.” Targeted public health interventions for adolescents and year-round monitoring are recommended to mitigate the high prevalence of suboptimal vitamin D status in Lithuania. Full article

Background: Vitamin D (25(OH)D) deficiency affects over one billion people globally and is associated with type 2 diabetes (T2D) and cardiometabolic diseases. However, causal relationships remain unclear, as vitamin D supplementation has shown limited benefit in reducing the risk of T2D. Genetic studies have identified variants that influence circulating 25(OH)D levels, but whether genetically determined vitamin D status predicts cardiometabolic outcomes remains uncertain. Methods and Results: Using multi-ethnic populations from the UK Biobank (471,861) and the Asian Indian Diabetic Heart Study (3486), we performed genome-wide univariate and polygenic risk score (PRS)-based bidirectional MR analyses to determine the causal association between vitamin D and T2D. A polygenic score of vitamin D–raising alleles did not affect the risk of T2D or cardiovascular disease. In contrast, a higher T2D PRS was strongly associated with an increased risk for 25(OH)D deficiency. Genetically instrumented per SD increase in T2D PRS was predicted to significantly (p = 9.5 × 10⁻³¹) reduce circulating 25(OH)D (β = −9.1 nmol/L; 95% CI: −8.9 to −9.3). The ancestry-specific univariate MR and sensitivity analyses confirmed that vitamin D levels reduced significantly with increasing T2D risk across all ancestries. Conclusions: Our findings suggest low circulating vitamin D levels are unlikely to causally predict T2D risk but may serve as a marker for secondary prevention in endocrine and cardiovascular health. Instead, genetic susceptibility to T2D appears to contribute to vitamin D insufficiency, which may lead to cardiovascular complications. Further studies are needed to clarify the mechanisms underlying vitamin D deficiency in diabetes. Full article

This study evaluated the effects of dietary supplementation with 25-hydroxyvitamin D₃ (25-OH-D3), canthaxanthin (Cx), copper (Cu), and gluco-oligosaccharides (GO) on performance, egg quality, fertility, and hatchability of broiler breeder hens during early production (30 to 41 weeks of age). A total of 210 breeder hens and 21 males were allocated to three dietary treatments. Birds were fed a standard broiler breeder diet (control) or the same diet in which 0.5 kg/MT of an additive premix replaced sand. This premix supplied 16.6–17.7 mg/kg canthaxanthin (Cx) and 3700–4700 IU/kg 25-OH-D3 in Treatment 1, and 9.2–11.1 mg/kg Cx and 4100–4700 IU/kg 25-OH-D3 in Treatment 2. Treatment 2 also included Cu and GO (≥44 mg/g within the additive), with Cu provided at industry-standard levels. Each treatment consisted of seven replicates, with birds housed in floor pens containing 10 females and 1 male per replicate. Hen performance was recorded weekly, while egg quality was assessed at 30, 35, and 41 weeks. Fertility and hatchability were evaluated at 30 and 41 weeks. Treatment 2 improved lay rate, albumen height, Haugh unit, and feed conversion ratio (FCR) at selected time points. Both supplemented diets consistently produced darker yolk color compared with the control. Supplementation consistently enhanced yolk color, whereas effects on albumen height, Haugh unit, shell thickness, and FCR were observed only at specific ages or weeks. Lay rate differed among treatments only at week 40, with a trend observed at week 41. Fertility and hatchability were not significantly affected by dietary treatment. Full article

Background/Objectives: The aim of this study was to systematically synthesize and quantitatively estimate the mean serum 25-hydroxyvitamin D concentrations across populations in Kazakhstan and to examine variations according to age group, health status, and geographic region. In addition, we specifically evaluated healthy subgroups to establish reference estimates that may be useful for future epidemiological surveillance and public health planning. Methods: A systematic review and meta-analysis was conducted in accordance with the PRISMA 2020 guidelines. PubMed, Scopus, ScienceDirect, and Google Scholar were searched through March 2026 without date restrictions. Studies reporting the mean serum vitamin D concentrations among Kazakhstani populations were included. Random-effects meta-analysis was performed in R. Subgroup analyses were conducted by age group, health status, and geographic region. Meta-regression, influence diagnostics, publication bias assessment, JBI risk-of-bias evaluation, and GRADE certainty-of-evidence assessment were performed. Results: Sixteen studies comprising 28 groups and 5771 participants were included. The pooled mean serum 25(OH)D concentration in the overall cohort was 22.3 ng/mL (95% CI: 19.3–25.3), while the healthy cohort demonstrated a slightly higher pooled mean of 24.4 ng/mL (95% CI: 20.3–28.4). Adolescents had the lowest vitamin D levels among all age groups. Significant regional variability was observed, and meta-regression identified male participant proportion as a significant moderator (p = 0.03). Heterogeneity was extremely high across analyses (I² ≈ 99.9%). Conclusions: Mean serum 25(OH)D concentrations were generally within the insufficient range across the included study groups in Kazakhstan, including healthy subgroups. However, because the certainty of evidence was very low and between-study heterogeneity was extreme, the findings should be interpreted cautiously. These results support the need for standardized national surveillance and locally evaluated public health policy considerations, including targeted supplementation for high-risk groups, screening strategies where clinically indicated, and assessment of food fortification options. Full article

This study evaluated the association between vitamin D3 levels, transplanted kidney function, and body composition in 315 stable renal transplant recipients (median 7.7 years post-transplant). The biochemical profile included eGFR, PTH, calcium, phosphorus, and 25(OH)D₃ levels. Vitamin D status was defined as deficiency (<20 ng/mL), insufficiency (20–30 ng/mL), or optimal (>30 ng/mL). Body composition was assessed via bioelectrical impedance analysis, capturing parameters such as BMI, visceral fat area, and phase angle. Multivariable quantile regression models were used to assess the associations between clinical/metabolic parameters and graft function. Vitamin D3 supplementation was prescribed in 61.5% of patients, with 49.7% receiving active analogues and 50.3% cholecalciferol. Results showed that 25(OH)D₃ levels did not correlate with graft function in the total population, and no significant differences in eGFR were observed regarding vitamin D status. In multivariable models, 25(OH)D₃ levels correlated significantly only with calcium levels. No significant correlations were observed between vitamin D and transplant vintage, age, eGFR, or any anthropometric and body composition parameters. Full article

Background: Acute kidney injury (AKI) is a frequent and prognostically important complication of cardiac surgery, yet early risk stratification remains challenging. The purpose of this prospective exploratory study was to determine whether preoperative vitamin levels differ in patients who develop cardiac surgery-associated AKI. Methods: Consecutive patients scheduled for cardiac surgery due to coronary artery disease and/or severe aortic stenosis between October 2024 and July 2025 were included. Fourteen patients (16.1%) had preoperative eGFR below 60 mL/min. Preoperative serum levels of vitamin A (retinol), vitamin E (α-tocopherol), and vitamin D (25-hydroxyvitamin D3) were measured. Results: A total of 87 patients (72 males (82.8%) with a median (Q1–Q3) age of 66 (61.5–71) years) were included in the study. Cardiac surgery-associated AKI occurred in 36 (41.4%), as a mild and transient impairment, with only two patients with a more severe stage requiring temporary renal replacement therapy. Patients who developed AKI had significantly higher preoperative retinol levels (p = 0.046). Retinol concentrations correlated positively with preoperative creatinine (Spearman’s rho 0.321, p = 0.002), postoperative day 0 creatinine (Spearman’s rho 0.333, p = 0.002), and postoperative day 1 creatinine (Spearman’s rho 0.268, p = 0.012), and negatively with preoperative eGFR (Spearman’s rho −0.288, p = 0.007). Tocopherol and 25(OH)D3 did not differ significantly between subgroups. No difference in vitamin levels was observed between patients with and without diabetes. Conclusions: Increased preoperative retinol levels were associated with cardiac surgery-associated AKI and correlated with perioperative renal dysfunction. Retinol may reflect impaired kidney handling of retinol and identify increased renal vulnerability in cardiac surgery patients. Retinol may represent a hypothesis-generating biomarker of cardiac surgery-associated AKI risk that warrants confirmation in larger cohorts. Full article

Bisphenol A (BPA) is a typical endocrine disruptor that poses a significant threat to ecosystems. Therefore, it is crucial to develop an efficient and environmentally friendly degradation technology. In this study, a novel bimetallic oxide-loaded GAC (Granulated Activated Carbon) particle electrode (CuFe₂O₄@GAC) was designed and applied to a three-dimensional electro-Fenton (3D-EF) system for efficient removal of BPA. The bimetallic synergistic effect of Cu and Fe was used to promote the Fenton reaction and enhance the efficiency of hydroxyl radical ·OH generation. The results show that under conditions of 20 g/L CuFe₂O₄@GAC, pH = 3, 10 mA/cm², and an electrode spacing of 2.0 cm, a BPA removal rate of over 93% (20 mg/L) was achieved within 45 min. The prepared CuFe₂O₄@GAC exhibits good stability, maintaining an 86.2% BPA degradation rate over five cycle experiments. The catalytic mechanism and degradation pathways were further analyzed through characterization methods such as radical quenching experiments, XPS analysis, EPR, and LC-MS detection. Radical quenching experiments confirmed that ·OH radicals play a significant role in the decomposition of BPA. Based on the identification of intermediates, a possible decomposition pathway for BPA was proposed. Toxicity analysis indicated that the toxicity of most intermediates was significantly lower than that of BPA. This work provides an efficient and energy-saving strategy for BPA removal. Full article

Background/Objectives: Dioscorea batatas Decne (yam), which contains various bioactive compounds, has been utilized in the cosmetics industry, while most of the peel of D. batatas (DBP) is discarded without further use. Recent studies have shown that DBP contains higher levels of bioactive substances than the rhizome flesh. The aim of this study was to evaluate the skin biological activities of DBP extracts obtained using 70% ethanol (70% EtOH DBP), 95% ethanol (95% EtOH DBP), and ethyl acetate (EA DBP), with particular attention to their antioxidant-associated protective effects. Methods: Skin-related bioactivities of DBP extracts prepared using ultrasonic extraction were evaluated using in vitro tyrosinase and matrix metalloproteinase-1 (MMP-1) assays, alpha-melanocyte-stimulating hormone (α-MSH)-induced melanogenesis in B16F10 cells, ultraviolet B (UVB)-irradiated HaCaT viability assays, and Western blot analysis of pro-collagen type I alpha 1(Pro-COL1A1) and MMP-1 in HDF cells. In addition, the ABTS and DPPH radical scavenging activities of DBP extracts and representative DBP derivatives were assessed. Results: DBP extracts inhibited tyrosinase activity in vitro and reduced melanogenesis in B16F10 cells. DBP extracts also protected skin cells from UVB by increasing the viability of UVB-irradiated HaCaT cells. In UVB-irradiated HDF cells, DBP extracts restored Pro-COL1A1 expression and suppressed MMP-1 levels. Additionally, DBP extracts inhibited MMP-1 activity in a concentration-dependent manner. The DBP extracts themselves exhibited ABTS and DPPH radical scavenging activities, with EA DBP showing the highest vitamin C equivalent antioxidant capacity among the tested extracts. Representative DBP-derived phenanthrene compounds also showed radical scavenging activities, supporting the antioxidant potential of peel-derived phytochemicals. Conclusions: These findings indicate that DBP extracts possess skin-whitening and anti-photoaging effects and suggest that these protective activities may be associated with the antioxidant potential of both DBP extracts and DBP derivatives. Full article

The active vitamin D metabolite, 1,25-dihydroxycholecalciferol [1,25(OH)₂D], exerts its biological effects through binding to the vitamin D receptor (VDR), a ligand-activated transcription factor regulating the expression of genes involved in calcium and phosphate homeostasis, immune modulation, and cell proliferation and differentiation. In addition to direct transcriptional regulation, 1,25(OH)₂D signaling also involves epigenetic mechanisms. A total of 90 studies were included in this narrative review, comprising experimental studies (n = 45), observational studies (n = 17), population-based studies (n = 8), interventional studies (n = 15), and mixed-design studies (n = 5). Experimental studies in cell cultures and animal models demonstrate that 1,25(OH)₂D may affect several major epigenetic regulatory pathways, including chromatin remodeling, DNA methylation, histone modifications, and the expression of non-coding RNAs, particularly microRNAs. Preclinical evidence suggests that the epigenetic actions of 1,25(OH)₂D are involved in metabolic regulation, immune responses, bone development, fibrotic processes, carcinogenesis, ageing, and fetal programming. However, evidence from observational studies and randomized controlled trials remains limited and inconclusive. Some studies have reported alterations in miRNA expression, methylation of selected loci, and epigenetic age markers. The clinical relevance of 1,25(OH)₂D–mediated epigenetic regulation has not yet been fully established. The interpretation of available findings is limited by substantial heterogeneity in study populations, exposure and intervention protocols, environmental factors, interindividual variability in response to vitamin D supplementation associated with genetic polymorphisms and methylation status, and the restricted range of analyzed cell types. This subject requires randomized controlled trials integrating molecular endpoints with clinically relevant outcomes. Full article

Background and Objectives: Urinary tract infections (UTIs) represent one of the most frequently encountered bacterial infections in clinical practice. Although vitamin D (vit D) is recognised for its immunomodulatory properties, its relationship with the spectrum of uropathogens remains unclear. This study investigated the distribution of UTI-causing pathogens in relation to serum vit D status and demographic variables including age, sex, season, and year of presentation at a tertiary hospital in the Eastern Mediterranean. Materials and Methods: A retrospective cross-sectional analysis was conducted on 942 adult patients with culture-confirmed UTIs at a university hospital in Cyprus between January 2019 and December 2024. Serum 25-hydroxyvitamin D [25(OH)D] levels were classified as deficient (≤20 ng/mL), insufficient (20–29.9 ng/mL), or sufficient (≥30 ng/mL) according to Turkish Endocrinology Society (TEMD) guidelines. Pathogen distribution was correlated with vit D category, sex, age group, season, and year using chi-square analysis and multivariable logistic regression. Timing of urine culture collection (at admission vs. more than 48 h after admission), catheter use, upper vs. lower urinary tract classification, and comorbidity data were recorded for each patient. Results: Escherichia coli was the most frequently isolated uropathogen (48.83%), followed by Klebsiella pneumoniae (18.79%) and Enterococcus faecalis (11.89%). No statistically significant association was found between vit D level and uropathogen type (p = 0.504). Infections were more prevalent in females (70.49%) and in patients aged over 70 years (56.26%). Vit D deficiency was present in 47.98% of the cohort. Catheter-derived specimens accounted for 35.1% of cultures. Upper tract infection was diagnosed in 233 patients (24.7%) and lower tract infection in 709 patients (75.3%). The most frequent comorbidities were hypertension (48.4%), diabetes mellitus (33.1%), and chronic kidney disease (21.0%); on multivariable analysis, diabetes mellitus (adjusted OR = 1.4) and chronic kidney disease (adjusted OR = 1.6) were independently associated with K. pneumoniae infection. In vit D-deficient patients, K. pneumoniae infection risk was significantly higher during winter in unadjusted analysis (OR = 1.8; 95% CI: 1.3–2.5) and remained elevated after multivariable adjustment (aOR = 1.6; 95% CI: 1.1–2.3). Vit D levels showed significant seasonal variation (p < 0.001), with lower values in winter (18.6 ng/mL) and higher values in summer (28.4 ng/mL). Conclusions: On multivariable analysis, no statistically significant association was found between vit D level and uropathogen species overall (χ² = 13.291; p = 0.504); a seasonal interaction was observed between vit D deficiency and Klebsiella infections in winter. UTI risk was highest in elderly and female patients. These findings point to the need for considering seasonal and dietary factors in UTI management and call for prospective investigation. Full article