Serum 25OHD Research Articles

SERUM PARATHORMONE, VITAMIN D AND CARDIOVASCULAR RISK FACTORS

Objective: The aim of this study is to evaluate the associations of serum 25-OHD and PTH concentrations with blood pressure and hypertension mediated target organ damage including left ventricular hypertrophy (LVH) and carotid intima-media thickness (IMT). Design and method: This observational retrospective study included 98 patients admitted at Hypertension Research Center of Federico II University Hospital in Naples without CKD. We collected serum 25-OHD, PTH, creatinine, BMI, lipid profile, blood glucose and office blood pressure. All patients underwent carotid doppler ultrasound and echocardiography. Results: Mean age of the participants was 53±17 years and 69% were men. Pearson's correlation analysis indicated that PTH levels correlated directly with age, diabetes, dyslipidemia, hypertension, fasting glucose, on statin therapy, left ventricular mass and inversely with the GFR, total cholesterol, LDL and vit D level. Vit. D levels correlated inversely with PTH, diabetes and carotid plaque. Multivariate regression models indicated that PTH was significantly associated with higher fasting glucose and with vit D while Vit D was associated with lower GFR and PTH level. Conclusions: In a population at high cardiovascular risk, Vit. D and PTH are not directly associated with hypertension but might influence association with other cardiovascular risk factors and markers.

Causal associations between insulin-like growth factor 1 and vitamin D levels: a two-sample bidirectional Mendelian randomization study.

Insulin-like growth factor 1 (IGF-1) plays a vital role in the attainment and maintenance of bone mass throughout life and is closely related to the stature of children. 25-Hydroxyvitamin D (25-OHD) is an intermediate of vitamin D (Vit D) metabolism and a key indicator of Vit D nutritional status. Multiple studies have revealed that IGF-1 levels undergo a non-significant increase after Vit D supplementation. Here, we analyzed the causal and reverse causal relationships between 25-OHD and IGF-1 levels using Mendelian randomization (MR). Two-sample MR was used to estimate an unconfounded bidirectional causal relationship between the level of IGF-1 and those of Vit D and 25-OHD. Single nucleotide polymorphisms (SNPs) were filtered from genome-wide association studies (GWAS) after a comprehensive search of the Integrative Epidemiology Unit GWAS database. Several MR methods were employed, including inverse-variance weighted (IVW) method, and a sensitivity analysis was undertaken to detect whether pleiotropy or heterogeneity biased the MR results. Genetically predicted IGF-1 was found to have a causal association with Vit D and serum 25-OHD levels, where Vit D and serum 25-OHD levels increased with increasing IGF-1 concentrations (Vit D: IVW β:0.021, 95% CI: 0.005-0.036, p = 7.74 × 10-3; 25-OHD: IVW β: 0.041, 95% CI: 0.026-0.057, p = 2.50 × 10-7). A reverse causal effect was also found, indicating Vit D and serum 25-OHD have a positive causal relationship with IGF-1 (Vit D: IVW β:0.182, 95% CI: 0.061-0.305, p = 3.25 × 10-3; 25-OHD: IVW β: 0.057, 95% CI = 0.017-0.096, p = 4.73 × 10-3). The sensitivity analysis showed that horizontal pleiotropy was unlikely to bias the causality in this study (MR-Egger: Vit D intercept p = 5.1 × 10-5, 25-OHD intercept p = 6.4 × 10-4 in forward analysis; Vit D intercept p = 6.6 × 10-4, 25-OHD intercept p = 1.9 × 10-3 in reverse analysis), and a leave-one-out analysis did not identify evidence of bias in the results. The results of the MR analysis provide evidence that IGF-1 has positive causal and reverse causal relationships with Vit D and serum 25-OHD, respectively, in European populations. Our findings also provide guidance for the prevention and treatment of short stature and other related diseases.

Vitamin D testing in children and adolescents in Victoria, Australia: are testing practices in line with global recommendations?

ObjectiveTo describe changing primary care ordering of serum 25-hydroxyvitamin D (25OHD) tests in Australian children.DesignLongitudinal, population-based descriptive study of 25OHD testing using a large administrative dataset of pathology orders and...

Quantification of 25OHD in serum by ID-LC-MS/MS based on oriented immobilization of antibody on magnetic materials.

Magnetic nanomaterials are widely used, but co-adsorption of impurities will lead to saturation. In this study, the aim was to prepare a magnetic nano-immunosorbent material based on orienting immobilization that can purify and separate 25-hydroxyvitamin D (25OHD) from serum and provides a new conceptof samplepretreatment technology. Streptococcus protein G (SPG) was modified on the surface of the chitosan magnetic material, and the antibody was oriented immobilized using the ability of SPG to specifically bind to the Fc region of the monoclonal antibody. The antigen-binding domain was fully exposed and made up for the deficiency of the antibody random immobilization. Compared withthe antibody in the random binding format, this oriented immobilization strategy can increase the effective activity of the antibody, and the amount of antibody consumed is saved to a quarter of the former. The new method is simple, rapid, and sensitive, without consuming a lot of organic reagents, and can enrich 25OHD after simple protein precipitation. Combining with liquid chromatography-tandem mass spectrometry (LC-MS/MS), the analysis can be completed in less than 30 min. For 25OHD2 and 25OHD3, the LOD was 0.021 and 0.017 ng mL-1, respectively, and the LOQ was 0.070 and 0.058 ng mL-1, respectively. The results indicated that the magnetic nanomaterials based on oriented immobilization can be applied as an effective, sensitive, and attractive adsorbent to the enrichment of serum 25OHD.

Genotype-dependent impact of dietary vitamin D3 on laying hens

ABSTRACT Vitamin D3 has an integral part in calcium and phosphorus homoeostasis, which in turn plays a key role in egg production of hens. The present study aimed to investigate whether an additional vitamin D3 supplementation improves the laying performance and egg quality of hens according to their genetic potential. For this purpose, four layer lines (low performing: R11 and L68; high performing: WLA and BLA) supplemented either with 300 or 3000 IU vitamin D3 per kg feed were compared concerning serum 25-hydroxyvitamin D3 (25-OHD3), calcium, phosphorus and alkaline phosphatase (ALP), laying performance and egg quality. The higher supplementation of vitamin D3 increased 25-OHD3 serum concentrations in all genotypes, except for R11 and WLA hens in week 49, and also elevated vitamin D3 and 25-OHD3 content in the egg yolk (p < 0.05). In week 29, 3000 IU vitamin D3 decreased pooled least squares means (LSMeans) of serum calcium concentrations considering all genotypes and increased the ALP concentrations in BLA hens (p < 0.05). Considering the whole experimental period daily egg mass of R11 hens was increased by an additional vitamin D3 supplementation (p < 0.001). Regarding all genotypes and the whole experimental period the pooled LSMeans of breaking strength of eggs from hens fed 3000 IU vitamin D3 were higher than those of hens fed 300 IU (p = 0.044). In conclusion, present results give evidence that the higher vitamin D3 supplementation might have genotype-dependently beneficial effects on calcium and phosphorus homoeostasis of hens, which might improve feed efficiency in the early laying period and promote the persistence of the laying period irrespectively of genotype. The increase of serum 25-OHD3 by the higher vitamin D supplementation supported the higher transfer of vitamin D in the egg yolk and improved genotype-dependently the breaking strength of the eggshell.

Associations between lumbar bone mineral density, serum 25-hydroxyvitamin D and history of kidney stones in adults aged 30–69 years in the USA (NHANES 2011–2018)

ObjectivesMost kidney stones contain calcium, which is closely associated with human bone health. Therefore, we aimed to determine the relationship between the history of kidney stones and human bone health....

Genetic correlation, causal relationship, and shared loci between vitamin D and COVID-19: A genome-wide cross-trait analysis.

Observational studies have shown that vitamin D supplementation reduces the risk of COVID-19 infection, yet little is known about the shared genomic architectures between them. Leveraging large-scale genome-wide association study (GWAS)summary statistics, we investigated the genetic correlation and causal relationship between genetically determined vitamin D and COVID-19 using linkage disequilibrium scoreregression and Mendelian randomization (MR)analyses, and conducted a cross-trait GWAS meta-analysis to identify the overlapping susceptibility loci of them. We observed a significant genetic correlation between genetically predicted vitamin D and COVID-19(rg = -0.143, p = 0.011), and the risk of COVID-19infection would decrease by 6% for every 0.76 nmol L-1 increase of serum 25 hydroxyvitamin D (25OHD)concentrations in generalized MR (OR = 0.94, 95%CI: 0.89-0.99, p = 0.019). We identified rs4971066 (EFNA1) as a risk locus for the joint phenotype of vitamin D and COVID-19.In conclusion, genetically determined vitamin D is associated with COVID-19. Increased levels of serum 25OHD concentration may benefit the prevention and treatment of COVID-19.

The association of serum 25-hydroxyvitamin D levels with early neonatal morbidity and mortality in late preterm infants monitored in the neonatal intensive care unit

(LP) infants (born between 34 0/7 and 36 6/7 weeks of gestational age) monitored in the neonatal intensive care unit (NICU).&#x0D; Patients and Methods: This retrospective study was conducted by reviewing live-born LP neonates from singleton pregnancies. The&#x0D; infants were monitored and treated in our hospital’s NICU between June 2016 and June 2019.&#x0D; Results: Maternal age at delivery was higher among infants with adequate vitamin D levels than among those with deficient vitamin D&#x0D; levels (P=0.007). A weak positive correlation was found between maternal age at childbirth and neonates’ vitamin D levels (r=0.296).&#x0D; The rate of low-birth-weight deliveries was greater in babies with sufficient vitamin D levels than in those with deficient levels. There&#x0D; was a weak negative association between the number of stools on the day that the infants’ serum 25-hydroxyvitamin D (25-OHD)&#x0D; levels were taken and their vitamin D level (P=0.027, r=-0.244).&#x0D; Conclusions: A significant correlation was shown between serum 25-OHD levels and maternal age and low birth weight in LP&#x0D; neonates. Upon examining the influence of vitamin D levels on the number of defecations per day, no significant difference was&#x0D; detected; however, a weak negative association was identified between them.

Evaluation of Serum Vitamin D Levels Among Patients with Viral Warts

Objective: To evaluate serum levels of 25-hydroxyvitamin D (25-OHD) in patients with viral warts.&#x0D; Study Design: Comparative cross-sectional study.&#x0D; Place and Duration of Study: Dermatology Department, Fauji Foundation Hospital, Rawalpindi Pakistan, from Jul to Dec 2020.&#x0D; Methodology: One hundred patients were included in the study, 50 with viral warts (Group-1) and 50 without warts (Group2). Our study included both male and female patients of 10 to 60 years of age. Three categories were made according to their serum vitamin D levels. First, all participants were tested for serum vitamin D levels using ELISA.&#x0D; Results: In Group-1, 20(40%) had insufficient, and 25(50%) had deficient vitamin D levels. A statistically significant decrease in serum 25-OHD levels (p = 0.004) was found in patients with viral warts. In Group-2, 9(18%) had insufficient, and 2(4%) had deficient vitamin D levels. The mean serum vitamin D level was 22.61±10.11 in Group-1 and 45.12±24.60 in Group-2, resulting in a significant difference between patients with viral warts and those without viral warts regarding serum vitamin D levels (p=0.004).&#x0D; Conclusion: Patients with viral warts have deficient vitamin D levels.

Effects of Short-Duration Artificial Ultraviolet B Exposure on 25-Hydroxyvitamin D3 Concentrations in Domestic Rabbits (Oryctolagus cuniculus).

Vitamin D is an important hormone that can be acquired through diet, exposure to ultraviolet B (UVB) radiation, or a combination of these methods. In domestic rabbits (Oryctolagus cuniculus), both methods appear viable, but there is limited research evaluating the effects of UVB on this species. Previous studies found that 12 h of artificial UVB radiation significantly increased 25-hydroxyvitamin D3 (25-OHD3) concentrations over time. While these findings suggest UVB can be beneficial in rabbits, this form of radiation can also be detrimental to vertebrates. The purpose of this study was to determine if shorter-duration UVB could elicit a similar physiological response in rabbits while minimizing potential negative effects. Six rabbits were used for this pilot study. The baseline serum 25-OHD3 was measured for each rabbit and following 14 days of 6 h/day exposure to artificial UVB, a second 25-OHD3 sample was collected. There was a significant increase (p = 0.001) in serum 25-OHD3 over time (Baseline: 27.7 ± 8.1 nmol/L; Day 14: 79.8 ± 9 nmol/L). This study affirmed that 6 h of UVB produced 25-OHD3 concentrations similar to those found in rabbits exposed to 12 h of UVB. Future studies should continue to determine how the duration of UVB exposure affects 25-OHD3 concentrations.

Vitamin D levels in children with cerebral palsy.

The aim of this study was to assess serum vitamin D levels and related factors in children with cerebral palsy (CP). One hundred and nineteen children with CP between the ages of 1 year to 10 years 9 months who were admitted to the children's inpatient rehabilitation unit of a tertiary rehabilitation hospital between January 1, 2017, and December 31, 2018, were included in this study. Demographic and clinical characteristics were obtained from the patient files. CP types and serum 25 hydroxyvitamin D (25OHD) levels were recorded. Gross Motor Function Classification System (GMFCS) was used to assess the functional level. Mean age was 5.1±2.9 years. Forty-two (35.3%) were girls, 105 (88.3%) were spastic, and 14 (11.7%) were ataxic and mixed type CP. Mean GMFCS level was 4 (IQR:2). Thirty-one (26.1%) were getting extra liquid feed while the rest were eating a normal diet. Mean serum 25OHD level was 27.4±15.7 (3-79) ng/mL. Vitamin D levels were normal in 68 children (57.1%), whereas 36 (30.3%) had vitamin D insufficiency and 15 (12.6%) showed vitamin D deficiency. Those whose serum vitamin D levels were within a normal range had a median age of 3.8 (IQR:4.2) years. On the other hand, mean age was 6.4 (4.3) years for those with low vitamin D level (p < 0.0001). Vitamin D level was 19.8 (21.4) ng/mL in those (n = 88) who had regular diets, whereas it was 31.0 [16] ng/mL in those (n = 31) who were getting extra liquid feed (p = 0.015). There was no statistically significant correlation between vitamin D level and gender, GMFCS, CP type, season or antiepileptic drug treatment. A binary logistic regression model showed that older age and having only regular meals were significant risk factors for low vitamin D. In this study, 42.9% of the children with CP had low vitamin D. Older children with CP or those who had regular diets were higher risk groups in terms of low vitamin D.

Vitamin D Status in Diabetic Moroccan Children And Adolescents: a Case-control Study

Background: Type 1 diabetes mellitus (T1DM) incidence is currently increasing worldwide, and different environmental players along with genetic predisposition, could be involved as powerful triggers of this disease onset. In this study, we aim to shed the light on the relationship between 25OHD deficiency and T1DM. Patients and methods: A case-control study was laid out to compare serum 25OHD level between T1DM patients and controls. A total of 147 T1DM patients aged under 19 years old were recruited from our Endocrinology-Diabetology and Nutrition department between October 2014 and December 2019. A total of 147 controls were randomly enlisted from clinical biochemistry laboratory of our center, and were carefully matched. The levels of 25OHD in the serum were determined in T1DM patients and nondiabetic controls. Results: Average serum 25OHD concentration was established in both groups; reaching 19,29 ±6,13 ng/ml in the control arm and 15,02 ± 6,48 ng/ml in the selected group with T1DM independently of the disease duration. However, the mean serum 25OHD concentration was not significantly different between the two T1DM subgroups according to diabetes duration below or above 5 years, and 25OHD concentration remained lower either in winter or summer months. A negative correlation was noticed between HbA1c and serum 25 OHD concentration in T1DM patients and was statistically significant (p<0,05). Conclusion: Key messages on the importance of vitamin D status, particularly in diabetic children and adolescents, should be spread widely in order to start a suitable vitamin supplementation, and establish guidelines regarding its timing at adequate recommended doses..

Very Low and High Levels of Vitamin D Are Associated with Shorter Leukocyte Telomere Length in 148,321 UK Biobank Participants.

Background: Shorter leukocyte telomere length (LTL) is observed in multiple age-related diseases, which are also associated with vitamin D deficiency (i.e., osteosarcopenia, neurocognitive disorders, cancer, osteoarthritis, etc.), suggesting a close association between vitamin D and LTL. In this study, we examined the relationship between vitamin D levels and LTL in older participants of the UK Biobank. Methods: Data were collected from the UK Biobank. Participants aged 60 and older (n = 148,321) were included. Baseline LTL was measured using a multiplex qPCR technique and expressed as the ratio of the telomere amplification product (T) to that of a single-copy gene (S) (T/S ratio). Serum 25-hydroxyvitamin D (25OHD) was stratified by z score and linked to LTL in a linear regression model adjusting for covariates. Results: Compared to the medium level, a low (in the range of 16.6 nmol/L, 29.7 nmol/L) or extremely low (≤16.6 nmol/L) level of serum 25OHD was associated with shorter LTL: 0.018 SD (standardized β = -0.018, 95% CI -0.033 to -0.003, p = 0.022) and 0.048 SD (standardized β = -0.048, 95% CI -0.083 to -0.014, p = 0.006), respectively. Additionally, the high serum 25OHD groups (>95.9 nmol/L) had 0.038 SD (standardized β = -0.038, 95% CI -0.072 to -0.004, p = 0.030) shorter mean LTL than the group with medium 25OHD levels. The associations above were adjusted for multiple variables. Conclusions: In this population-based study, we identified an inverted U-shape relationship between LTL and vitamin D status. Our findings could be affected by unmeasured confounders. Whether high or low vitamin D-associated shorter LTL is mechanistically related to age-related conditions remains to be elucidated.

Vitamin D and SARS-CoV-2 Infection: SERVE Study (SARS-CoV-2 Exposure and the Role of Vitamin D among Hospital Employees)

BackgroundRecognition of the role of vitamin D in immune function has led to interest in its relationship with SARS-CoV-2 infection. Although clinical studies to date have had conflicting results, many individuals currently take high doses of vitamin D to prevent infection. ObjectiveThe goal of this study was to investigate the relationship between serum 25-hydroxyvitamin D (25OHD) and vitamin D supplement use with incident SARS-CoV-2 infection. MethodsIn this prospective cohort study, 250 health care workers were enrolled at a single institution and observed for 15 mo. Participants completed questionnaires every 3 mo regarding new SARS-CoV-2 infection, vaccination, and supplement use. Serum was drawn at baseline, 6, and 12 mo for 25OHD and SARS-CoV-2 nucleocapsid antibodies. ResultsThe mean age of the participants was 40 y, BMI 26 kg/m2, 71% were Caucasian, and 78% female. Over 15 mo, 56 participants (22%) developed incident SARS-CoV-2 infections. At baseline, ∼50% reported using vitamin D supplements (mean daily dose 2250 units). Mean serum 25OHD was 38 ng/mL. Baseline 25OHD did not predict incident SARS-CoV-2 infection (OR: 0.98; 95% CI: 0.80, 1.20). Neither the use of vitamin D supplements (OR: 1.18; 95% CI: 0.65, 2.14) or supplement dose was associated with incident infection (OR: 1.01 per 100-units increase; 95% CI: 0.99, 1.02). ConclusionIn this prospective study of health care workers, neither serum 25OHD nor the use of vitamin D supplements was associated with the incident SARS-CoV-2 infection. Our findings argue against the common practice of consuming high-dose vitamin D supplements for the presumed prevention of COVID-19.

Causal association between vitamin D and diabetic neuropathy: a Mendelian randomization analysis.

Vitamin D has been linked to diabetic neuropathy (DN) in previous epidemiological observational studies, however, their findings are inconsistent. The causal relationship between vitamin D and DN remains unknown. In this study we aim to investigate the causal association of serum 25-hydroxyvitamin D (25OHD) and DN. Based on summary statistics from publicly available genome-wide association studies (GWAS) database, we detected the genetic correlation between serum 25OHD levels and DN by a two-sample Mendelian randomization (MR) analysis. The inverse-variance weighted (IVW) method was used as the primary analysis, weighted median and MR-Egger were applied as complementary methods for MR estimates. In addition, we took sensitivity analyses including Cochran's Q test, MR-Pleiotropy Residual Sum and Outlier (MR-PRESSO) and leave-one-out analysis to ensure that we obtained stable and reliable results. Our MR study showed no significant genetic association between serum 25OHD levels and DN (OR = 1.13, 95% CI = 0.81-1.57, P = 0.46). Furthermore, in the reverse direction analysis, we did not find a significant causal effect of DN and serum 25OHD levels (OR = 0.99, 95% CI = 0.98-1.00, P = 0.09). Results of MR-Egger, Weighted Median were consistent with those of the IVW method. The sensitivity analysis suggesting that no significant heterogeneity and genetic pleiotropy was observed. Our results provided no evidence to support the causal association of serum 25OHD levels with DN.

Sun Exposure Score and Vitamin D Levels in Moroccan Women of Childbearing Age.

Sunlight exposure is an essential source of vitamin D for many humans. However, hypovitaminosis D is a global public health problem. This study aimed to develop and validate a sun exposure score (SES) and correlate it with serum 25-hydroxyvitamin D levels in women of childbearing age. One hundred and sixty women aged 18 to 45 years residing in Meknes, Morocco, were included. A questionnaire estimating the sun exposure score and blood analysis of serum 25-OHD concentration were performed. The questionnaire's reliability and construct validity were evaluated using Cronbach's alpha and factor analysis. Spearman's test was used to assess the correlation between SES and 25-OHD levels. The score's reliability and construct validity were good, with Cronbach's alpha values >0.70 and factorial saturation ranging from 0.696 to 0.948. Serum 25-OHD levels were significantly associated with the total sun exposure score, and all SES domains (Rho was 0.615 (p < 0.0001), 0.307 (p < 0.0001), 0.605 (p < 0.0001), and 0.424 (p < 0.0001) for total SES, indoor exposure domain, outdoor exposure domain, and sun protection practice domain, respectively). In addition, median 25-OHD levels increased significantly when sun exposure was changed from insufficient to sufficient (p < 0.0001). The results suggest that the sun exposure score could be used as a clinical tool to assess vitamin D levels in women of childbearing age.

Evaluation of Therapies for Secondary Hyperparathyroidism Associated with Vitamin D Insufficiency in Chronic Kidney Disease

Introduction: Parathyroid hormone-lowering responses after administration of three different therapies capable of raising serum total 25-hydroxyvitamin D (25OHD) were evaluated in patients with secondary hyperparathyroidism (SHPT), vitamin D insufficiency (VDI), and stage 3 or 4 chronic kidney disease (CKD). Methods: Sixty-nine adult subjects with intact parathyroid hormone (iPTH) ≥85 and <500 pg/mL and VDI (25OHD <30 ng/mL) were randomized after ≥4-week washout to 2 months of open-label treatment with: (1) extended-release calcifediol (ERC) 60 μg/day; (2) immediate-release calcifediol (IRC) 266 μg/month; (3) high-dose cholecalciferol (HDC) 300,000 IU/month; or (4) paricalcitol plus low-dose cholecalciferol (PLDC) 1 or 2 μg and 800 IU/day, used as reference hormone replacement therapy. Serum 25OHD, calcium (Ca), phosphorus (P), plasma iPTH, and adverse events were monitored weekly. No clinically significant differences were observed at baseline between treatment groups. Results: Sixty-two subjects completed the study per protocol (PP; 14–17 per group). Mean (SD) 25OHD and iPTH at baseline were 20.6 (6.6) ng/mL and 144.8 (90) pg/mL, respectively. Mean 25OHD increased at end of treatment (EOT) to 82.9 (17.0) ng/mL with ERC (p < 0.001) and 30.8 (11.6) ng/mL with HDC (p < 0.05), but remained unchanged with IRC and PLDC. EOT 25OHD levels reached ≥30 ng/mL in all subjects treated with ERC and in 44% with HDC. All subjects attained EOT 25OHD levels ≥50 ng/mL with ERC versus none with other therapies. iPTH response rates at EOT (≥10, 20 or 30% below baseline) were similar for ERC and PLDC; rates for IRC and HDC were much lower. No significant changes from baseline were observed in ionized or corrected total Ca or P in any group. One episode of hypercalcemia (>10.3 mg/dL) occurred with PLDC. Hyperphosphatemia (>5.5 mg/dL) occurred once with ERC, eight times with HDC, 3 times with IRC, and twice with PLDC. Conclusion: ERC was highly effective in both raising serum 25OHD and decreasing iPTH in patients with SHPT, VDI, and stage 3 or 4 CKD. iPTH-lowering response rates with ERC were similar to daily PLDC, the reference therapy; rates with IRC or HDC were significantly lower. ERC is an attractive alternative to vitamin D hormone therapy in CKD patients.

Vitamin D Levels and Risk of Male Factor Infertility: A Mendelian Randomization Study.

No consensus exists about the causal relationship between vitamin D (VD) and male factor infertility due to heterogeneity and confounding factors even in randomized controlled trials (RCTs). This study aimed to investigate the causal association between 25 hydroxyvitamin D (25OHD) levels and male factor infertility through Mendelian randomization (MR) and provide complementary information for optimization of future RCTs. Two-sample MR analyses with four steps were performed. Single-nucleotide polymorphisms (SNPs) for VD were extracted from 417,580 Europeans in the UK Biobank, and the summary-level data of male factor infertility (825 cases and 85,722 controls) were extracted from the FinnGen. Totally 99 SNPs robustly associated with the 25OHD were included, and a 1-unit increase in genetically predicted natural-log transformed 25OHD levels was associated with decreased risk of male factor infertility (odds ratio [OR], 0.62; 95% confidence interval [CI], 0.44-0.89; p=0.010), which was consistent in all three sensitivity analyses (MR-Egger, weighted median, and weighted mode methods). The conclusion still stands after removing SNPs which explained more variation in the male factor infertility than the 25OHD (OR, 0.61; 95% CI, 0.42-0.88; p=0.009; n=62), and which were associated with confounders (body mass index, type 2 diabetes, smoking, and coronary artery diseases) of male factor infertility (OR, 0.58; 95% CI, 0.39-0.85; p=0.005; n=55). VD supplement to increase serum 25OHD levels may be clinically beneficial for male factor infertility in the general population. The well-designed RCTs should be performed in priority to address this question.

Prevalence and risk factors for vitamin D insufficiency in 6-12-month-old infants: a cross-sectional study in Southern Thailand

BackgroundVitamin D is an essential micronutrient for bone mineralization and bone growth in children. There have been few studies to date of vitamin D status in infants aged 6–12 months in Southeast Asian countries.AimTo examine the prevalence of vitamin D insufficiency (VDI, including vitamin D deficiency) in healthy infants and the risk factors for VDI in southern Thailand.MethodsA cross-sectional study was carried out in 120 healthy infants aged 6–12 months and their mothers. Blood samples were obtained for measurement of serum calcium, phosphate, alkaline phosphatase, albumin, parathyroid hormone and 25-hydroxyvitamin D (25OHD) levels. The mothers were interviewed for their infants feeding intake, sunlight exposure, type of dress, and sunscreen use. Chi-square and t-test were used to compare between groups for categorical and continuous variables, respectively. Pearson correlation was used to identify the relationship between serum levels of 25OHD of the infants and other biochemical variables of the infants and serum levels of maternal 25OHD. Logistic regression analysis was used to identify the factors associated with vitamin D status.ResultsThe prevalence of VDI in our study infants was high at 28.3%, all of whom were mainly breastfed infants. Subgroup analysis of the mainly breastfed infants found that the risk factors for VDI were maternal VDI and a short duration of sunlight exposure. The serum 25OHD levels of the mainly breastfed infants were significantly positively correlated with the maternal serum 25OHD levels (r = 0.49, p-value < 0.01) and with sunlight exposure duration (r = 0.40, p-value < 0.01).ConclusionsThe prevalence of VDI was high in 6–12-month-old infants, particularly those who were mainly breastfed from VDI mothers, and who had short durations of sunlight exposure. As breast milk contains adequate amounts of most important vitamins and growth factors, breastfeeding is still encouraged for infants with 400 IU vitamin D daily supplementation to prevent VDI.

The role of vitamin D in periodontal health and disease.

Vitamin D plays an essential role in calcium and bone metabolism, immune regulation and possesses profound anti-inflammatory effects. Evidence suggests that low serum vitamin D is associated with increased severity of periodontitis, a chronic inflammatory condition characterised by destruction of the supporting tissues surrounding the tooth, which has several shared risk factors with other chronic non-communicable diseases. The biological functions of vitamin D are mediated by its strong anti-microbial, anti-inflammatory, and host modulatory properties. Experimental periodontitis models involving targeted deletion of 1α-hydroxylase, the enzyme responsible for the conversion of inactive substrate to active 1,25(OH)2 D3 (calcitriol), showed augmented alveolar bone loss and gingival inflammation. Vitamin D receptor (VDR) gene polymorphisms have also been associated with increased severity of periodontitis. Thus, the involvement of vitamin D in the pathogenesis of periodontitis is biological plausible. Clinical studies have consistently demonstrated an inverse relationship between serum 25OHD3 and periodontal disease inflammation. However, due to the paucity of well-designed longitudinal studies, there is less support for the impact of vitamin D status on periodontal disease progression and tooth loss. The evidence emphasises the importance of maintaining vitamin D sufficiency in supporting periodontal health. This review aims to first examine the biological mechanisms by which vitamin D might influence the pathogenesis of periodontal disease and second, discuss the clinical evidence which implicate the role of vitamin D in periodontal disease.