Background: Vitamin D is a fat-soluble steroid that influences cardiovascular health by affecting lipid metabolism. Since dyslipidemia is a key risk factor for cardiovascular disease (CVD), our study aimed to explore the relationship between vitamin D levels and lipid parameters, considering the effects of age and gender. Methods: In this cross-sectional study of 47,778 outpatients, we analyzed correlations between two forms of vitamin D—25-hydroxyvitamin D (25(OH)D) and 1,25-dihydroxyvitamin D (1,25(OH)₂D)—and lipid parameters, including low-density lipoprotein (LDL), high-density lipoprotein (HDL), and total cholesterol (TC). Subgroup analyses by age and gender provided additional insights. Results: Results showed that 25(OH)D levels were negatively correlated with LDL and TC across the cohort. This association was particularly evident in men over 50, whereas women showed a positive correlation with LDL and TC before age 50 and a negative correlation after. HDL levels positively correlated with 25(OH)D across all age groups, with the strongest association in postmenopausal women. In contrast, 1,25(OH)₂D showed a positive correlation only with HDL in individuals over 50, with no significant correlation with LDL or TC in any age group. Conclusions: In conclusion, findings from this cross-sectional study underscore an association between elevated levels of 25(OH)D and more favorable lipid profiles, characterized by reduced LDL and total cholesterol, as well as increased HDL levels. This association is particularly pronounced among individuals over 50 years of age and postmenopausal women.

Target values for 25-hydroxy vitamin D and 1,25(OH)₂D or 1,25-dihydroxy vitamin D remain a topic of debate among clinicians. We analysed data collected from December 2012 to April 2020 from two cohorts. Cohort A, comprising 455,062 subjects, was used to investigate the relationship between inflammatory indicators (white blood cell [WBC] count and C-reactive protein [CRP]) and 25(OH)D/1,25(OH)₂D. Cohort B, including 47,778 subjects, was used to investigate the connection between 25(OH)D/1,25(OH)₂D and mineral metabolism markers (phosphate, calcium, and intact parathyroid hormone [iPTH]). Quadratic models fit best for all tested correlations, revealing U-shaped relationships between inflammatory indicators and 25(OH)D and 1,25(OH)₂D. Minimal CRP and WBC counts were observed at 1,25(OH)₂D levels of 60 pg/mL and at 25(OH)D levels of 32 ng/mL, as well as of 42 ng/mL, respectively. iPTH correlated inversely with both 1,25(OH)₂D and 25(OH)D, while phosphate as well as calcium levels positively correlated with both vitamin D forms. Calcium-phosphate product increased sharply when 25(OH)D was more than 50 ng/mL, indicating a possible risk for vascular calcification. Multiple regression analyses confirmed that these correlations were independent of confounders. This study suggests target values for 25(OH)D between 30–50 ng/mL and for 1,25(OH)₂D between 50–70 pg/mL, based particularly on their associations with inflammation but also with mineral metabolism markers. These findings contribute to the ongoing discussion around ideal levels of vitamin D but require support from independent studies with data on clinical endpoints.

Background: Periostin is a matricellular protein. Elevated serum concentrations of periostin have been reported in patients with various cardiovascular diseases, including heart failure. Patients with end-stage renal disease have a substantially increased risk for cardiovascular diseases. However, there is a lack of clinical studies to clarify the prognostic significance of systemic periostin on all-cause mortality in patients with end-stage renal disease on hemodialysis. Methods: 313 stable end-stage renal disease patients were recruited and followed for five years concerning all-cause mortality. At baseline, we collected blood samples and clinical data. Serum periostin concentrations were measured using a certified ELISA. Results: The optimal cut-off value for serum periostin regarding all-cause mortality, calculated through ROC analysis, was 777.5 pmol/l. Kaplan-Meier survival analysis using this cut-off value demonstrated that higher periostin concentrations are linked to higher all-cause mortality (log-rank test: P = 0.002). Subgroup analysis revealed that serum periostin concentrations only affected all-cause mortality in male but not in female patients (P = 0.002 in male patients and P = 0.474 in female patients). Multivariate Cox regression analyses, adjusted for confounding factors, likewise showed that elevated serum periostin concentrations were positively associated with all-cause mortality in male (P = 0.028) but not in female patients on hemodialysis (P = 0.313). Conclusion: Baseline serum periostin is an independent risk factor for all-cause mortality in male patients with chronic renal disease on hemodialysis.

Background: Vitamin D is increasingly recognized as a key immunomodulatory nutrient, influencing innate and adaptive immune responses. While 25-hydroxyvitamin D [25(OH)D] is widely used to assess vitamin D status, the active form, 1,25-dihydroxyvitamin D [1,25(OH)₂D], may exert distinct effects on immune function. This study investigates the concentration-dependent and sex-specific relationships of both vitamin D metabolites with systemic inflammatory markers in a large clinical cohort. Objectives: To characterize the associations of 25(OH)D and 1,25(OH)₂D with total white blood cell (WBC) count and leukocyte subtypes, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Methods: We conducted a retrospective cross-sectional analysis of 125,537 adults (37.9% male; age 18–89 years) from routine laboratory diagnostics collected between 2014 and 2020 in Germany. Serum 25(OH)D and 1,25(OH)₂D were measured using standardized chemiluminescent immunoassays. Inflammatory markers were assessed via automated hematology. Multivariable-adjusted linear and non-linear regression models were used to assess associations, adjusting for age, sex, and season. Results: Neutrophils and Monocytes: Displayed U-shaped associations with both 25(OH)D and 1,25(OH)₂D. Neutrophil counts were lowest at 25(OH)D levels of ~40–60 nmol/L and increased significantly at both lower and higher extremes (p < 0.001). Lymphocytes: Inverse relationship with 25(OH)D (p < 0.001), and an inverse U-shaped relationship with 1,25(OH)₂D, peaking at ~90 pmol/L, with counts decreasing at both lower and higher levels (p < 0.001). Sex-specific analysis revealed that the relationship between 1,25(OH)₂D and lymphocyte count remained independent only in men, Eosinophils and Basophils: Demonstrated consistently negative correlations with both forms of vitamin D across all concentration ranges (p < 0.001). Conclusions: Our findings reveal distinct, concentration-dependent associations between vitamin D metabolites and leukocyte profiles, with evidence for nonlinear and sex-specific immunological effects. Both low and high levels of 25(OH)D and 1,25(OH)₂D were linked to increased neutrophil and monocyte counts, suggesting that vitamin D excess, like deficiency, may be linked to low-grade inflammation. These data are hypothesis-generating and suggest that personalized monitoring of vitamin D status may be relevant for future research on immune health, particularly in populations at risk for inflammatory or metabolic disease, but they do not provide a basis for clinical decision-making.

Wang J, et al. Clin Exp Vaccine Res. 2025 Dec;15:e7. https://doi.org/10.7774/cevr.2026.15.e7