Search Results (829)

Background and Aims: Preterm newborns are particularly susceptible to hypovitaminosis D, potentially impairing bone mineralization. In Thailand, data on its prevalence and standardized supplementation protocols remain limited. This study aimed to compare the efficacy of two vitamin D3 dosages (400 IU/day vs. 800 IU/day) in improving serum vitamin D concentrations and metabolic bone parameters in preterm newborns. Methods: A randomized controlled trial was conducted in preterm newborns born at ≤32 weeks’ gestation or with birth weight ≤1500 g. Preterm newborns were randomized to receive either 400 IU or 800 IU/day of vitamin D3. Serum 25-hydroxyvitamin D (25(OH)D) was measured using electrochemiluminescence immunoassay (ECLIA). Metabolic bone parameters—including calcium, phosphorus, alkaline phosphatase, and albumin—were assessed at baseline and again at six weeks of age. Results: Of the 38 enrolled infants, baseline 25(OH)D levels were comparable between groups (14.8 ± 4.8 ng/mL in the 800 IU/day group vs. 14.7 ± 6.9 ng/mL in the 400 IU/day group). At six weeks, the 800 IU group demonstrated significantly higher 25(OH)D levels (47.3 ± 21.0 ng/mL vs. 32.0 ± 14.2 ng/mL; p = 0.013), with a large effect size (Cohen’s d = 0.85) and the difference-in-differences of +15.7 ng/mL. The prevalence of hypovitaminosis D declined from 89% to 5% in the 800 IU/day group and from 74% to 32% in the 400 IU/day group (p = 0.036). No significant differences in metabolic bone parameters or signs of toxicity were observed. Conclusions: Vitamin D3 supplementation at 800 IU/day significantly improved vitamin D status and reduced hypovitaminosis D in preterm newborns, without observed toxicity. Full article

Background: Cervical dysplasia is a pre-malignant condition of the uterine cervix and is highly prevalent in Sub-Saharan Africa; especially affecting HIV-infected Black women. The anti-dysplastic effect of vitamin D hormones in cervical dysplasia is poorly understood. Therefore, we conducted a cross-sectional case–control observational study to assess the relationship between serum 25-hydroxycholecalciferol (25(OH)D) and cervical dysplasia, amongst Black women with and without HIV infection. Methods: The study participants attended a gynaecologic oncology clinic at an academic hospital in Pretoria, South Africa (n = 109). Patient clinical data were obtained during consultation. Cervical dysplasia was identified by cytology (PAP smear) which classified the case group as high-grade squamous epithelial lesions (HSILs), and the control group as <HSIL. Serum biochemistry measured 25(OH)D and its covariate biochemical variables. The data were statistically modelled to adjust for clinical and biochemical covariates, identify a significant relationship (p ≤ 0.05) between 25(OH)D and cervical dysplasia, and analyse subgroup interaction between HIV status and cervical dysplasia. Results: The data showed high levels of vitamin D insufficiency and deficiency in Black women with and without HIV infection. After covariate adjustment, 25(OH)D demonstrated an inverse relationship with HSIL in HIV-uninfected Black women. Furthermore, an interaction effect between women with and without HIV infection was observed. Conclusions: The role of 25(OH)D in the primary prevention of cervical dysplasia in Black women without HIV infection is promising, and dosing strategies require investigation. Also, future studies exploring the immunomodulatory role of 25(OH)D in cervical dysplasia in HIV-infected women is warranted. Full article

Objective: The aim of this study was to investigate the relationship between primary monosymptomatic enuresis nocturna (PMNE) and vitamin D deficiency in children. Patients and Methods: This retrospective case–control study included 307 PMNE patients aged 5–18 years and 254 age- and sex-matched healthy control subjects. Demographic data and biochemical parameters of the participants were obtained from hospital records. Serum 25(OH)D3 levels were measured using the chemiluminescence immunoassay method. The Mann–Whitney U test, Chi-square test, Pearson correlation and multivariate logistic regression analysis were used for statistical analyses. Results: Serum 25(OH)D3 levels were significantly lower in the PMNE group compared to the control group (p < 0.001). The rate of vitamin D deficiency was higher in the PMNE group. Vitamin D deficiency (OR: 3.164, 95% CI: 1.195–8.378, p = 0.02) and family history of enuresis (OR: 2.790, 95% CI: 1.01–5.8, p = 0.04) were found to be independent associated factors for PMNE. A significant negative correlation was found between serum vitamin D level and weekly bedwetting frequency (r = −0.377, p < 0.001). Conclusions: Serum 25(OH)D3 levels were significantly lower in the PMNE group (p < 0.001, Cohen’s d = 0.89). It is recommended that vitamin D levels should be routinely evaluated in children with PMNE and the potential benefits of vitamin D supplementation should be investigated in prospective studies. Full article

Background and Objectives: Vitamin D deficiency is linked to adverse outcomes in chronic obstructive pulmonary disease (COPD). Limited data exist on how vitamin D levels vary by disease severity during acute exacerbations of COPD (AECOPDs). This study aimed to determine whether the vitamin D status during AECOPDs—alongside inflammatory and hematological biomarkers—is associated with COPD severity. Materials and Methods: This observational study included 105 AECOPD hospitalized patients, stratified according to GOLD stages 1–2, 3, and 4. Blood samples were collected to measure serum vitamin D—as 25-hydroxyvitamin D [25(OH)D], acute phase reactants, serum calcium, and selected hematological parameters. Inter-group differences were evaluated using Kruskal–Wallis tests, with Spearman correlations applied for intra-strata associations. ROC analysis and logistic regression assessed the discriminatory power of significant biomarkers. Results: C-reactive protein (CRP) and fibrinogen concentrations were elevated across all COPD stages, whereas calcium and vitamin D remained consistently below normal. Interleukin (IL)-6 and 25(OH)D levels varied significantly with COPD stage (p = 0.033 and p = 0.047, respectively), with a marked drop from GOLD stage 3 to stage 4. High-IL-6 patients revealed significantly elevated CRP (p = 0.045), erythrocyte sedimentation rate (ESR) (p = 0.032), fibrinogen (p = 0.011), and procalcitonin (p = 0.044). The strongest correlations were seen between CRP, ESR, and fibrinogen (r_s ≥ 0.58, p ≤ 0.05), indicating a coordinated acute-phase response that weakened with advancing disease. Serum 25(OH)D was a significant independent predictor of COPD severity (AUC = 0.631, p = 0.048), while IL-6 had a weaker predictive value, losing significance in the combined regression model. Conclusions: Vitamin D deficiency is more pronounced in very severe COPD, serving as a potential clinical indicator of disease severity during exacerbation episodes. Full article

Background: Vitamin D deficiency (VDD) during pregnancy has been associated with various obstetric complications, including preeclampsia, gestational diabetes, and premature rupture of membranes. However, its potential link to placental abruption remains underexplored. The aim of this study was to investigate whether low maternal vitamin D levels are associated with an increased risk of placental abruption in pregnancies considered otherwise low-risk. Methods: We conducted a cross-sectional study involving 248 pregnant women who were admitted for delivery at a public hospital in Athens, Greece. Serum levels of 25-hydroxyvitamin D [25(OH)D] were measured upon admission. Levels below 30 ng/mL were classified as insufficient. Although this threshold corresponds to insufficiency according to the Endocrine Society, for the purposes of this study, levels < 30 ng/mL were treated as indicative of vitamin D deficiency in order to capture broader physiological implications. Cases of placental abruption were identified based on obstetric history and clinical documentation at the time of delivery. A Chi-square test was used to assess the association between vitamin D status and placental abruption, and a multivariate logistic regression model was applied to control for potential confounders, including hypertensive disorders of pregnancy, smoking, and preterm birth. The potential role of vitamin D supplementation during pregnancy was also explored as part of the analysis. Results: Our analysis revealed that women with VDD had a significantly higher incidence of placental abruption (p < 0.05). In the multivariate model, VDD remained an independent risk factor (adjusted OR: 3.2, 95% CI: 1.1–9.6). Additional risk factors that showed significant associations with placental abruption included pregnancy-induced hypertension and maternal smoking. Conclusions: These findings support the hypothesis that insufficient maternal vitamin D levels may contribute to adverse pregnancy outcomes, including placental abruption. Further prospective studies are warranted to clarify the causal mechanisms and to evaluate whether early detection and correction of vitamin D deficiency could serve as a preventive strategy in prenatal care. Full article

Background/Objective: Depression is a widespread and complex disorder, constituting a major public health concern due to its significant impact on mental health. Because of the limitations of major depressive disorder (MDD) treatment, recent research on depression management has focused on identifying new therapeutic strategies. The effects of vitamin D on the brain, mediated through various mechanisms, suggest the potential implication of vitamin D in the pathophysiology of depression. In this systematic review, our objective was to evaluate the correlation between serum levels of 25-hydroxyvitamin D (25(OH)D) and depression based on evidence from cross-sectional and cohort studies. Furthermore, we also assessed the effect of vitamin D supplementation in relation to depressive symptoms, using data from randomised controlled trials (RCTs). Methods: To achieve the proposed objective, we have compiled a report that includes a selection of empirical evidence necessary to review the relationship between vitamin D and depression. In this regard, relevant articles were searched on platforms such as PubMed, MDPI, ResearchGate, Springer Link, Springer Open, and ScienceDirect. A total of 13,976 records, published between 2008 and 2024, were initially identified through database searches. After the study selection process, performed according to the PRISMA guidelines, 70 articles were included in the systematic review. Results: According to most cross-sectional and cohort studies, the results highlight an inverse relationship between serum 25(OH)D levels and the risk of depression, as well as the severity of depressive symptoms. An increase in serum 25(OH)D concentration is associated with an improvement in depression test scores, with vitamin D supplementation exerting a beneficial effect on both the incidence and the prognosis of depression. Conclusions: Based on current evidence which indicates the implications of vitamin D in the neurobiological mechanisms associated with depression, and the results obtained in most of the studies, which demonstrate an inverse relationship between serum 25(OH)D levels and the beneficial effect of vitamin D supplementation on depressive symptoms, vitamin D could represent an adjunctive therapy in the management of MDD. More rigorous studies, without methodological errors, are needed to correctly and definitively assess the impact of vitamin D in relation to depression. Full article

Background: To characterize the clinical significance of vitamin D deficiency (VDD) detected in long COVID, a retrospective observational study was performed for outpatients who visited our clinic during the period from May 2024 to November 2024. Methods: Clinical trends in long COVID patients diagnosed with VDD who showed serum concentrations of 25-hydroxyvitamin D (25-OHD) lower than 20 ng/mL were compared with those in long COVID patients in a non-deficient vitamin D (NDD) group. Results: Of 126 patients with long COVID, 97 patients (female: 50) who had been infected during the Omicron phase were included. Sixty-six patients (68%) were classified in the VDD group. The median serum concentrations of 25-OHD were 14.8 ng/mL in the VDD group and 22.9 ng/mL in the NDD group. There were no significant differences between the two groups in terms of age, gender, BMI, severity of COVID-19, period after infection and vaccination history. Although the levels of serum calcium and phosphate were not significantly different between the two groups, the percentages of patients in the VDD group who complained of dizziness, memory impairment, palpitation and appetite loss were larger than those in the NDD group. Of note, the patients who complained of palpitation showed significantly lower concentrations of serum 25-OHD than those in the patients without palpitation (median: 11.9 vs. 17.3 ng/mL). Moreover, patients in the VDD group had significantly higher scores for physical and mental fatigue as well as higher scores for depressive symptoms. Conclusions: Collectively, VDD is involved in clinical manifestations of long COVID, particularly symptoms of palpitation, fatigue and depression. Full article

Polycystic ovary syndrome (PCOS), a common and multifactorial endocrine disorder in reproductive-aged women, is strongly associated with insulin resistance (IR) and type 2 diabetes mellitus (T2DM), and also affects up to one in four women with type 1 diabetes mellitus (T1DM). The current study explored the potential of Plantago ovata (P. ovata) seed ethanol extract (POEE) to modulate oxidative stress (OS), inflammatory responses, metabolic profiles, and hormonal levels in rat Streptozotocin (STZ)-induced DM and Letrozole (LET)-induced PCOS. Phytochemical analysis measured total phenolic content (TPC) and total flavonoid content (TFC) using HPLC-DAD-ESI MS for compound identification. POEE’s antioxidant activity was evaluated in vitro through DPPH, H₂O₂, FRAP, and NO scavenging assays. Rats received POEE, metformin, or Trolox (TX) for 10 days. PCOS confirmation was achieved via ultrasound and histopathology. Serum levels of OS markers (TOS, TAC, OSI, MDA, AOPP, 8-OHdG, NO, 3-NT, AGEs, and SH), inflammatory markers (NF-κB, IL-1β, IL-18, Gasdermin D, and IL-10), metabolic parameters (fasting blood glucose, lipid profile, and liver enzymes), and hormone levels (LH, FSH, estrogen, testosterone, and insulin) were assessed. Additionally, the Triglyceride–Glucose index (TyG) and HOMA-IR were calculated. POEE had a medium content of polyphenols and a good in vitro antioxidant effect. In vivo, POEE administration in diabetic rats led to a reduction in OS markers and an increase in antioxidant levels, alongside decreases in inflammatory cytokines, blood glucose levels, and transaminase activity and improvements in lipid profile. In the PCOS model, POEE treatment effectively reduced total OS and lowered levels of LH, FSH, and testosterone, while elevating estrogen concentrations and reducing insulin resistance. These therapeutic effects were dose-dependent, with higher doses producing more pronounced outcomes, comparable to those observed with metformin and TX treatment. Full article

Background: Vitamin D plays a key role in bone metabolism and immune regulation. Populations with restricted sun exposure or limited dietary intake are particularly vulnerable to vitamin D deficiency. Orthodox Christian nuns represent a unique group in this regard, due to traditional clothing, limited outdoor activity, and prolonged religious fasting. However, few studies have compared them with lay individuals following similar dietary practices. Objective: This study aimed to investigate predictors of serum 25-hydroxyvitamin D [25(OH)D] concentrations in two female populations: Orthodox Christian nuns and women from the general population practicing intermittent (religious or non-religious) fasting. We also aimed to develop predictive models of vitamin D status for each group based on lifestyle and biochemical parameters. Methods: A total of 85 women (40 Orthodox nuns and 45 laywomen), aged 30–50 years, were enrolled. Serum 25(OH)D, parathyroid hormone (PTH), calcium levels, and anthropometric indices, including body mass index (BMI), total body fat, and visceral fat, were measured. Dietary calcium and vitamin D intake, as well as sun exposure, were assessed using validated questionnaires. Separate stepwise multiple regression models were constructed for each group to identify independent predictors of 25(OH)D concentrations. An additional combined model, including all participants, was also explored. Results: PTH was the most significant predictor, negatively correlating with 25(OH)D concentrations in both groups (p = 0.038), highlighting its regulatory role in vitamin D metabolism. When analyzed separately, the model for Orthodox nuns showed stronger explanatory power (adjusted R² = 0.718; p = 0.013) compared with the control group (adjusted R² = 0.362; p = 0.038), with PTH emerging as a key predictor in both. Conclusions: Distinct predictors of vitamin D status were identified in each group, reflecting the complex interplay between lifestyle and physiological factors. These findings suggest that targeted interventions, such as addressing PTH regulation in fasting populations or enhancing sun exposure in the general population, may be more effective in preventing vitamin D deficiency depending on the context. Full article

Polycystic ovary syndrome (PCOS) and diabetes mellitus (DM) are prevalent endocrine disorders with overlapping pathophysiological mechanisms. Type 2 diabetes mellitus (T2DM) is commonly associated with PCOS, with both conditions strongly linked to insulin resistance (IR), while recent studies have also reported an increased prevalence of PCOS among women with type 1 diabetes mellitus (T1DM). This study evaluated the potential of Lythrum salicaria L. ethanol extract (LSEE) to mitigate oxidative stress (OS), inflammation, and metabolic and hormonal imbalances in separate experimental models of Streptozotocin (STZ)-induced DM and Letrozole (LET)-induced PCOS. LSEE underwent phytochemical analysis to quantify total phenolic and flavonoid content and HPLC-MS for polyphenols identification. In vitro, antioxidant capacity was investigated through FRAP, DPPH, NO, and H₂O₂ scavenging assays. Subsequently, in vivo, studies utilized STZ-induced DM and LET-induced PCOS rat models, with 10-day treatments of LSEE, metformin, or trolox (TX) administered by gavage. Dysregulation of hormonal profiles, ultrasound, and histological examinations confirmed PCOS development. At the end of the treatment period, serum samples were collected to assess OS markers (TOS, OSI, MDA, AOPP, 8-OHdG, NO, 3-NT, AGEs, TAR, SH) in both models. Inflammatory markers were also measured (IL-1β, NF-κB, IL-18, and Gasdermin D in DM and IL-1β, NF-κB, IL-18, and IL-10 in PCOS). Additionally, metabolic markers (glucose, lipids, TG-glucose index, liver enzymes) were assessed in DM rats, and hormones (LH, FSH, estrogen, testosterone, insulin, HOMA-IR) were determined in PCOS rats. LSEE demonstrated a high polyphenolic content and notable in vitro antioxidant activity. In vivo, it effectively reduced OS by lowering oxidant levels and enhancing antioxidant defenses, reduced inflammatory markers and blood glucose levels, and improved lipid profiles along with the TyG index and liver injury markers in diabetic rats. In PCOS rats, LSEE lowered the total oxidants, increased antioxidants, reduced LH, FSH, testosterone, and insulin, and increased estrogen levels. The effects exhibited a dose-dependent pattern, with higher doses producing more pronounced benefits comparable to those observed with metformin and TX. In conclusion, LSEE may be a promising complementary treatment for DM and PCOS. Full article

Background/Objectives: Chronic kidney disease–mineral and bone disorder (CKD-MBD) and systemic inflammation contribute to mortality in hemodialysis (HD) patients. The primary aim of this study was to determine whether specific CKD-MBD markers and inflammatory biomarkers are associated with increased mortality risk in HD patients. Methods: We conducted a retrospective cohort study on 63 stage 5D CKD patients undergoing maintenance HD. Serum intact parathyroid hormone (iPTH), soluble Klotho, calcium, phosphorus, 25(OH)D (25-hydroxyvitamin D), transforming growth factor-beta (TGF-β), vascular endothelial growth factor (VEGF), C-reactive protein (CRP), and interleukin-6 (IL-6) were analyzed. A Cox regression analysis assessed mortality predictors, and linear regression analysis evaluated CKD-MBD–inflammation correlations. Results: Lower iPTH (<329.3 pg/mL) levels were the only significant mortality predictor (p = 0.042). Other CKD-MBD markers (calcium, phosphorus, 25(OH)D, VEGF, TGF-β) did not impact survival. Soluble Klotho correlated positively with IL-6 (r = 0.57, p < 0.001), suggesting a compensatory inflammatory response. Conclusions: Our findings demonstrate that low iPTH levels and advanced age are independent predictors of mortality in hemodialysis patients. The positive association between soluble Klotho and IL-6 suggests a potential compensatory inflammatory response. These results highlight the need for further research to clarify underlying mechanisms and to explore novel therapeutic strategies. Full article

25-hydroxyvitamin D (25(OH)D) regulates lipid metabolism, and its decrease is proposed as a pathogenesis of metabolic syndrome, gestational diabetes mellitus (GDM), and eventually fetal adiposity. Decreased 25(OH)D is also linked with the development of gestational diabetes mellitus (GDM), which is associated with increased fetal adiposity. Fetuses are dependent on the supply of 25(OH)D from maternal circulation. However, the influence of maternal serum 25(OH)D on fetal adiposity remains unclear. This study aimed to investigate the association between maternal serum 25(OH)D and fetal adiposity. A prospective longitudinal study was conducted in a cohort of 89 (including 21 GDM) singleton pregnancies. Maternal blood samples were obtained at 10, 24, 30, and 36 weeks, and fetal ultrasonography was performed at 24, 30, and 36 weeks of gestation. Estimated fetal adiposity (EFA) was calculated as the average z-score of cross-sectional arm and thigh percentage fat area and anterior abdominal wall thickness as previously reported. The multiple linear regression analyses indicated that maternal 25(OH)D levels across gestation were not associated with EFA at 24 and 30 weeks, while maternal 25(OH)D at 24 weeks was inversely correlated with EFA at 36 weeks. Particularly, in the GDM group, maternal 25(OH)D levels at 10, 24, 30, and 36 weeks all showed a significant negative correlation with EFA at 36 weeks. Decreased maternal serum 25(OH)D level could be an early biomarker of increased fetal adiposity in late gestation, especially in diabetic pregnancies. Full article

Background/Objectives: The skeletal system reaches peak bone mass through modeling and remodeling processes, influenced by environmental, dietary, hormonal, and genetic factors. In children with endocrinopathies, disturbances in bone mass and mineralization may correlate with hormonal levels, but conditions like short stature or obesity can confound DXA results. This study aimed to assess the prevalence of decreased bone mineral density (BMD) in children with endocrine disorders and evaluate the impact of auxological and hormonal abnormalities on BMD. Methods: This study analyzed medical records of 148 children (mean age 11.85 ± 3.34 years); 73 girls and 75 boys). Conditions included obesity (22.9%), short stature (47.9%), precocious puberty (10.1%), and other diagnoses. Clinical data included primary diagnosis, height, body weight, pubertal stage, and serum concentrations of calcium, phosphate, alkaline phosphatase, 25OHD, PTH, osteocalcin, Crosslaps, TSH, fT4, IGF-1, IGF-BP3, cortisol, estradiol, testosterone, and bone age. DXA scans were performed at the total body less head (TBLH) and lumbar spine (Spine) projection. Results: Low bone mass (aBMD Z-score ≤ −2) was found in 34.46% at TBLH and 15.54% at the Spine. After height adjustment (HAZ adjustment), the prevalence of low bone mass decreased to 11.4% at TBLH and 4.1% at the Spine. In the short stature group, the normalization of Z-scores for height significantly reduced abnormal results. A positive correlation was found between DXA parameters and age, height standard deviation score (HSDS), BMI SDS, estradiol, testosterone, IGF-1, and IGF-BP3. A negative correlation existed between vitamin D and DXA parameters. Bone turnover markers (osteocalcin and Crosslaps) also negatively affected bone mass. No significant correlations were found with PTH, TSH, fT4, or cortisol. In children with growth retardation, lower aBMD_HAZ Z-scores were observed in those with decreased IGF-1. Positive correlations existed between BMI SDS, IGF-1, and adjusted aBMD Z-scores. Conclusions: Children with endocrine disorders, especially those with short stature, are at risk for bone mineralization disorders. Height normalization is crucial for accurate DXA interpretation and avoiding overdiagnosis. Positive influences on bone mass include height, BMI, IGF-1, estradiol, and testosterone, while negative factors include bone turnover markers and low vitamin D. Full article

Background: Vitamin D intake and synthesis are essential. Vitamin D deficiency is increasing across all age groups, raising concerns regarding public health. Serum 25(OH)D is measured to define vitamin D deficiency. However, its quantification in non-invasively collected biological matrices is still poorly studied. This study aimed to assess 25(OH)D levels in unconventional matrices using cost-effective analytical methods. Methods: Serum, urine, and saliva were collected from 62 healthy, non-smoking volunteers, 25–44 years of age. Biological samples were analysed using the Enzyme-Linked Immunosorbent Assay (ELISA). The serum was additionally analysed via the chemiluminescent microparticle immunoassay (CMIA), which was used as a benchmark. Results: We observed a linear correlation (Pearson r = 0.44; p = 0.05) between the benchmark and ELISA-measured 25(OH)D urinary levels. After stratification by sex, the correlation was stronger and significant only in females (Pearson r = 0.62; p = 0.04). Salivary 25(OH)D levels did not correlate with serum levels for both ELISA and CMIA measures. Subjects with a CMIA serum-based deficiency showed lower urinary 25(OH)D levels (p = 0.04). Conclusion: Our study opens up the possibility of using urinary 25(OH)D levels as a proxy measurement of vitamin D. Such an approach may allow future investigations on the association between environmental factors and vitamin D assessed in non-invasively collected biological matrices via cost-effective analytical methods. Full article

Background: Vitamin D deficiency is recognized as a significant public health concern, and it has been identified as one of the potentially modifiable risk factors for mild cognitive impairment (MCI). However, evidence regarding the relationship between vitamin D status and cognitive function remains conflicting. Objective: Therefore, this study aimed to examine the prevalence of vitamin D deficiency in the Thai elderly population and an association between vitamin D status and cognitive function, adiposity, and insulin sensitivity. Methods: This study enrolled participants aged 55–80 years with normal cognitive function (normal group) or MCI from the prospective cohort in the “Holistic approach of Alzheimer’s disease in Thai people (HADThai study)”. We used the baseline clinical data to determine the prevalence of vitamin D deficiency and its association between vitamin D status and cognitive function, adiposity, and insulin sensitivity. Results: A total of 718 subjects (71.9% women) with a mean age of 65.7 ± 5.8 years and a mean BMI of 23.9 ± 3.7 kg/m² were enrolled. There were 470 (65.5%) participants with normal cognitive function and 248 (34.5%) with MCI. Vitamin D status did not differ significantly between individuals with normal cognitive function and those with MCI. The prevalence of vitamin D deficiency (<20 ng/mL) and vitamin D inadequacy (<30 ng/mL) in both normal cognitive function and MCI was around 6.5% and 40.0%, respectively. While serum 25(OH)D concentrations were inversely associated with body mass index (BMI), body fat, %body fat, and the homeostasis model assessment of insulin resistance (HOMA-IR), no relationship was found between vitamin D status and cognitive function. Conclusions: Our study emphasized the high prevalence of vitamin D inadequacy among elderly individuals and an inverse association of vitamin D status and adiposity and insulin resistance. These findings emphasize the importance of addressing vitamin D deficiency in the elderly population to improve overall health outcomes. Nevertheless, our results do not support a direct role of vitamin D status in cognitive decline in this population. Further research, particularly studies with longer follow-up periods and the inclusion of patients with dementia with details of vitamin D supplementation, is needed to clarify the potential role of vitamin D in cognitive decline and neurodegenerative diseases. Full article