Association between serum 25-hydroxyvitamin D level and myopia in children and adolescents: a cross-sectional study.

Background: Prior reports have indicated an inconsistent relationship between vitamin D levels and myopia in children and adolescents with limited sample size. This study was undertaken to further clarify this relationship with a repeated cross-section study. Methods: The National Health and Nutrition Examination Survey (NHANES) database with samples <19 years old was utilized. Data on rates of myopia (spherical equivalent less than or equal to -1.0 D), serum 25-hydroxyvitamin D [25(OH)D] level (high performance liquid chromatography), and other key variables were extracted and analyzed. Three models were utilized to evaluate the dose response of vitamin D levels using stepwise logistic regression. Logistic regressions for sex subgroups and other covariates were also performed, and Forest plots were drawn. Results: Data were available from 6,814 children (49.5% girls; mean age: 14.9±1.85 years). The myopia and non-myopia differed in serum 25(OH)D level, gender, race, poverty income ratio (PIR), and body mass index (BMI). Serum 25(OH)D levels were negatively correlated with myopia [odds ratio (OR) =0.98, 95% confidence interval (CI): 0.77-0.99, P<0.05] regardless of sex. Although the relationship did not appear to be linear, there was a dose effect with higher serum 25(OH)D levels linked with lower rates of myopia. In addition, rates of myopia were increased in females compared with males (OR =1.12, 95% CI: 1.01-1.24, P=0.03), those with a high PIR (OR =1.08, 95% CI: 1.04-1.11, P<0.001), and those with high BMI (OR =1.19, 95% CI: 1.11-1.27, P<0.001). White ethnicity (OR =0.78, 95% CI: 0.68-0.90, P<0.001) and leisure-time exercise (OR =0.94, 95% CI: 0.92-0.97, P=0.02) were associated with lower rates of myopia. Conclusions: These findings indicate that higher serum 25(OH)D levels and increased amounts of leisure-time exercise are associated with lower rates of myopia in this group of children and adolescents. Meanwhile, female gender, high PIR level, and high BMI were associated with greater rates of myopia. The findings indicated that children and adolescents needed leisure-time exercise to lower the risk of myopia.

Association of serum 25-hydroxyvitamin d concentrations with all-cause and cause-specific mortality among individuals with depression: A cohort study.

BACKGROUND: Limited evidence exists on the relationship between vitamin D status and mortality in depressed patients. METHODS: This study investigates serum 25-hydroxyvitamin D [25(OH)D] concentrations in 8417 adults with depression among the National Health and Nutrition Examination Survey (NHANES, 2005-2018). Mortality outcomes were assessed through National Death Index records up to December 31, 2019. Cox proportional risk models estimated risk ratios (HR) and 95 % confidence intervals (CI) for all-cause, cardiovascular disease (CVD), and cancer mortality. Restricted cubic spline analyses explored the nonlinear association of serum 25(OH)D levels with mortality, using the likelihood ratio test for nonlinearity. RESULTS: The weighted mean serum 25(OH)D level was 66.40 nmol/L (95 % CI: 65.8, 67.0), with 36.3 % having deficient vitamin D (<50 nmol/L [20 ng/mL]). Over an average 7.16-year follow-up, 935 deaths were documented, including 296 CVD deaths and 191 cancer deaths. Higher serum 25(OH)D levels were associated with reduced all-cause mortality (HRs 0.55-1.00, p trend = 0.006) and cancer-specific mortality (HRs 0.36-1.00, p trend = 0.015) after multivariate adjustment. The relationship between serum 25(OH)D and all-cause mortality exhibited a nonlinear pattern (P for nonlinearity <0.001), with a 34 % lower risk for each unit increase in natural log-transformed 25(OH)D levels. Significant interactions were observed with age, antidepressant use, and diabetes status. CONCLUSIONS: Higher serum 25(OH)D levels were associated with decreased all-cause and cancer-specific mortality in depressed adults, particularly among younger individuals and those using antidepressants or without diabetes. Further research is essential to understand mechanisms and interventions related to vitamin D in depression.

Prevalence and risk factors of low vitamin D levels in children and adolescents with familial hypokalemic periodic paralysis.

Patients with familial hypokalemic periodic paralysis (HOKPP) experience episodes of reversible immobility and are at an increased risk of limited sunlight exposure, potentially leading to vitamin D deficiency. However, there is a lack of data on vitamin D levels in this population. We investigated serum vitamin D levels and their associated factors in children with HOKPP. This study included 170 genetically-confirmed children with HOKPP, aged 3-18 years, and 170 age-, sex-, and body mass index (BMI)-matched healthy controls from the Korean Channelopathy Study, a prospective controlled investigation. Anthropometric and clinical characteristics were recorded, and serum levels of calcium, ionized calcium, phosphorus, alkaline phosphatase, 25-hydroxyvitamin D, and intact parathyroid hormone (PTH) were analyzed. Vitamin D deficiency (< 20 ng/mL) was observed in 87.0% of the patients compared to 45.5% of the controls (P < 0.05) during the summer-fall season. During the winter-spring season, 91.7% of the patients and 73.4% of the controls were deficient (P < 0.05). A strong positive correlation was found between onset age of the first paralytic attack and vitamin D levels (r = 0.78, P < 0.01). Conversely, the frequency and duration of paralytic attacks were negatively correlated with vitamin D levels (r = -0.82 and r = -0.65, P < 0.01, respectively). Age, BMI, age at onset, frequency and duration of attacks, and PTH levels were independently associated with vitamin D levels (ß = -0.10, -0.12, 0.19, -0.27, -0.21, and -0.13, P < 0.05, respectively). CONCLUSIONS: Vitamin D deficiency was highly prevalent in children with HOKPP, and vitamin D levels correlated with various disease characteristics. We recommend routine screening for vitamin D levels in these patients to address this prevalent deficiency. Considering the high prevalence of vitamin D deficiency observed, further research on other diseases characterized by reversible immobility is warranted. WHAT IS KNOWN: • A correlation between immobility and low serum vitamin D levels has been established. However, the vitamin D status of patients with familial hypokalemic periodic paralysis (HOKPP) who experience periods of reversible immobility remains unknown. WHAT IS NEW: • Vitamin D deficiency was highly prevalent in children with HOKPP, and vitamin D levels correlated with various disease characteristics.

Relevance of Serum Levels and Functional Genetic Variants in Vitamin D Receptor Gene among Saudi Women with Gestational Diabetes Mellitus.

Background: This study explored the association between ApaI-TaqI Single Nucleotide Polymorphisms (SNPs) in a Vitamin D receptor (VDR) and the risk of Gestational Diabetes Mellitus (GDM) in Saudi women, along with the serum levels of vitamin D. Methods: Ninety women with GDM and 90 non-GDM women were enrolled, based on the inclusion and exclusion criteria for pregnant women enrolled in a single-center study. Blood samples were retrieved from 180 pregnant women using ethylenediaminetetraacetic acid (EDTA) tubes. Serum samples were used to measure the vitamin D, 25-hydroxyvitamin D (25(OH)D or calcidiol), and lipid profiles. Blood was used to measure the hemoglobin A1c levels and to isolate the DNA. The polymerase chain reaction (PCR) was performed for the ApaI (rs79785232), BsmI (rs1544410), FokI (rs2228570), and TaqI (rs731236) SNPs in the VDR gene using restriction fragment length polymorphism analysis. Validation was performed using Sanger sequencing. Statistical analyses were performed between the patients with and without GDM using various statistical software packages. Results: The Hardy-Weinberg equilibrium analysis was statistically significant (p > 0.05). The ApaI, BsmI, and TaqI SNPs were associated with alleles, genotypes, and different genetic models (p < 0.05). Vitamin D levels were associated with deficient levels (p = 0.0002), as well as with a normal and overweight body mass index (p = 0.0004). When vitamin D levels were measured with GDM covariates, the fasting plasma glucose (FPG) (p = 0.0001), postprandial blood glucose (PPBG) (p < 0.0001), oral glucose tolerance test (OGTT)-1 h (p = 0.005), high-density lipoprotein (p = 0.022), and low-density lipoprotein cholesterol (LDLc) (p = 0.001) levels were significantly different. When similar vitamin D levels were measured for each genotype, we confirmed that the ApaI SNP was associated with sufficient levels (p < 0.0001), whereas the BsmI, FokI, and TaqI (p < 0.05) were associated with insufficient levels. The logistic regression model confirmed that the first hour of the OGTT (p = 0.005) was strongly associated with GDM, whereas the analysis of variance confirmed that FPG and PPBG (p < 0.05) were strongly associated with all the SNPs evaluated in the VDR gene. Additionally, the second hour of the OGTT (p = 0.048) and LDLc (p = 0.049) were associated with the ApaI and FokI SNP. Moreover, the first hour OGTT (p = 0.045) and lipid profile parameters (p < 0.05) were associated. Haplotype analysis revealed positive associations among the examined SNPs, which seemed compatible with the hypothesis that variants and combinations of multiple SNP genotypes enhance the risk of GDM in women. Haplotype analysis revealed that different combinations of alleles, such as AGCC, CATT, CGTC, AGTC, and CATT (p < 0.05), were strongly associated. The linkage disequilibrium (LD) analysis showed a strong association with all combinations (p < 0.05). Among the gene-gene interactions, all possible combinations showed a positive association (p < 0.05). Conclusions: Low vitamin D levels were observed in women with GDM. The ApaI, BsmI, and TaqI SNPs were associated with genotype and allele frequencies (p < 0.05). Vitamin D and the SNPs in the VDR gene were associated, according to the ANOVA, logistic regression, haplotype analysis, LD analysis, and the generalized multifactor dimensionality reduction model (p < 0.05).

Mediation of BMI on 25-Hydroxyvitamin D Levels in U.S. Adults with Sugar-Sweetened Beverages Consumption.

Body mass index (BMI) as well as sugar-sweetened beverages (SSB) has been suggested to independently decrease 25-hydroxyvitamin D (25(OH)D). However, the relationship between SSB, BMI, and 25(OH)D is uncertain. This study aimed to investigate the potential mediating role of BMI in the association between SSB intake and 25(OH)D. A total of 4505 representative U.S. adults aged above 20 years and without liver conditions were selected from the 2013-2014 NHANES. All analyses were performed under survey modules with appropriate sampling weights. The prevalence of 25(OH)D insufficiency and deficiency was 37.8% and 24.1% in U.S. adults, respectively. Compared with non-SSB consumers, an increased risk of vitamin D deficiency was found in either heavy SSB consumers or soda consumers, respectively (aOR = 2.10, 95% CI = 1.25-3.54 in heavy SSB consumers; aOR = 1.61, 95% CI = 1.06-2.44 in soda consumers). Around 21.3% of the total effect of sugar intake from SSB on decreased 25(OH)D was explained by BMI. In conclusion, high total sugar intake from SSB and BMI independently contribute to lower 25(OH)D, and BMI mediates the inverse association between total sugar intake from SSB intake and 25(OH)D. Furthermore, an increased risk of having vitamin D deficiency was found in the population who consumed higher levels of sugar from SSB or soda drinks.

Hospital Outcomes in Patients Hospitalized for COVID-19 Pneumonia: The Effect of SARS-CoV-2 Vaccination and Vitamin D Status.

SARS-CoV-2 vaccination promises to improve outcomes for patients with COVID-19 pneumonia (most notably those with advanced age and at high risk for severe disease). Here, we examine serum 25-Hydroxyvitamin D (25(OH)D) status and outcomes in both old (>70 years) and young vaccinated (n = 80) and unvaccinated (n = 91) subjects, who were hospitalized due to COVID-19 pneumonia in a single center (Connolly Hospital Dublin). Outcomes included ICU admission and mortality. Serum 25(OH)D levels were categorized as D30 (<30 nmol/L), D40 (30-49.99 nmol/L) and D50 (≥50 nmol/L). In multivariate analyses, D30 was independently associated with ICU admission (OR: 6.87 (95% CI: 1.13-41.85) (p = 0.036)) and mortality (OR: 24.81 (95% CI: 1.57-392.1) (p = 0.023)) in unvaccinated patients, even after adjustment for major confounders including age, sex, obesity and pre-existing diabetes mellitus. While mortality was consistently higher in all categories of patients over 70 years of age, the highest observed mortality rate of 50%, seen in patients over 70 years with a low vitamin D state (D30), appeared to be almost completely corrected by either vaccination, or having a higher vitamin D state, i.e., mortality was 14% for vaccinated patients over 70 years with D30 and 16% for unvaccinated patients over 70 years with a 25(OH)D level greater than 30 nmol/L. We observe that high mortality from COVID-19 pneumonia occurs in older patients, especially those who are unvaccinated or have a low vitamin D state. Recent vaccination or having a high vitamin D status are both associated with reduced mortality, although these effects do not fully mitigate the mortality risk associated with advanced age.

Impact of Intravenous Iron Substitution on Serum Phosphate Levels and Bone Turnover Markers-An Open-Label Pilot Study.

The association between intravenous iron substitution therapy and hypophosphatemia was previously reported in patients with iron deficiency anemia. However, the extent of hypophosphatemia is thought to depend on the type of iron supplementation. We hypothesized that the intravenous application of ferric carboxymaltose and iron sucrose leads to a different longitudinal adaptation in serum phosphate levels. In this open-label pilot study, a total of 20 patients with inflammatory bowel diseases or iron deficiency anemia were randomly assigned to one of two study groups (group 1: ferric carboxymaltose, n = 10; group 2: iron sucrose, n = 10). Serum values were controlled before iron substitution therapy, as well as 2, 4, and 12 weeks after the last drug administration. The primary objective of the study was the longitudinal evaluation of serum phosphate levels after iron substitution therapy with ferric carboxymaltose and iron sucrose. The secondary objective was the longitudinal investigation of calcium, 25-hydroxyvitamin D (25(OH)D), intact parathyroid hormone, procollagen type 1 amino-terminal propeptide (P1NP), beta-CrossLaps (CTX), hemoglobin (Hb), iron, ferritin, and transferrin saturation levels. Two weeks after drug administration, phosphate levels were significantly lower (p < 0.001) in group 1 and ferritin levels were significantly higher (p < 0.001) in group 1. Phosphate levels (0.8-1.45 mmol/L) were below the therapeutic threshold and ferritin levels (10-200 ng/mL for women and 30-300 ng/mL for men) were above the therapeutic threshold in group 1. P1NP (15-59 µg/L) and CTX (<0.57 ng/mL) levels were above the therapeutic threshold in group 2. Four weeks after drug administration, significant differences were still observed between both study groups for phosphate (p = 0.043) and ferritin (p = 0.0009). All serum values except for Hb were within the therapeutic thresholds. Twelve weeks after drug administration, no differences were observed in all serum values between both study groups. Hb values were within the therapeutic threshold in both study groups. Serum 25(OH)D levels did not differ between both study groups throughout the whole study period and remained within the therapeutic threshold.

Effects of Climate, Sun Exposure, and Dietary Intake on Vitamin D Concentrations in Pregnant Women: A Population-Based Study.

BACKGROUND: Vitamin D deficiency (VDD) is a global micronutrient issue that commonly occurs in pregnant women, leading to adverse health outcomes. We examined the role of sunlight-related factors and dietary vitamin D intake on vitamin D concentrations among pregnant women in different climate zones. METHODS: We conducted a nationwide cross-sectional survey in Taiwan between June 2017 and February 2019. The data of 1502 pregnant women were collected, including sociodemographic information and characteristics related to pregnancy, diet, and sun exposure. Serum 25-hydroxyvitamin D concentrations were measured, and VDD was assessed as a concentration of less than 20 ng/mL. Logistic regression analyses were used to explore the factors associated with VDD. Furthermore, the area under the receiver operating characteristic (AUROC) curve was used to analyze the contribution of sunlight-related factors and dietary vitamin D intake to vitamin D status stratified by climate zones. RESULTS: The prevalence of VDD was 30.1% and was the highest in the north. Sufficient intake of red meat (odds ratio (OR): 0.50, 95% confidence interval (CI): 0.32-0.75; p = 0.002), vitamin D and/or calcium supplements (OR: 0.51, 95% CI: 0.39-0.66; p < 0.001), sun exposure (OR: 0.75, 95% CI: 0.57-0.98; p = 0.034), and blood draw during sunny months (OR: 0.59, 95% CI: 0.46-0.77; p < 0.001) were associated with a lower likelihood of VDD. Additionally, in northern Taiwan, which is characterized by a subtropical climate, dietary vitamin D intake (AUROC: 0.580, 95% CI: 0.528-0.633) had a greater influence on vitamin D status than did sunlight-related factors (AUROC: 0.536, 95% CI: 0.508-0.589) with a z value = 51.98, p < 0.001. By contrast, sunlight-related factors (AUROC: 0.659, 95% CI: 0.618-0.700) were more important than dietary vitamin D intake (AUROC: 0.617, 95% CI, 0.575-0.660) among women living in tropical areas of Taiwan (z value = 54.02, p < 0.001). CONCLUSIONS: Dietary vitamin D intake was essential to alleviate VDD in the tropical region, whereas sunlight-related factors played a greater role in subtropical areas. Safe sunlight exposure and adequate dietary vitamin D intake should be promoted appropriately as a strategic healthcare program.

Effects of Vitamin D on Cardiovascular Risk and Oxidative Stress.

INTRODUCTION: Vitamin D has been primarily studied as an important factor influencing bone and calcium metabolism. Metabolites of vitamin D are essential for whole-body calcium homeostasis, maintaining serum calcium levels within a narrow range by regulating this process in the bones and gut. Nevertheless, its deficiency is also related to increased risk of type 2 diabetes mellitus (T2DM), metabolic syndrome (MS), and cardiovascular disease (CVD)-with increased visceral adipose tissue and body mass index (BMI), as well as the frequently associated hypercholesterolemia. It has been reported that vitamin D levels are inversely related to cardiovascular (CV) risk in men and women. However, the effects of vitamin D on distinct outcomes in women and the dose of supplementation needed to improve clinical endpoints have not been established. 25-Hydroxyvitamin D [25(OH)D] reduces systemic inflammatory mediators in CVD and favors the release of anti-inflammatory cytokines from the immune system. In addition, 25(OH)D can be primarily converted into calcitriol (1,25-dihydroxycholecalciferol [1,25(OH)2D]) in the kidneys through the action of the 1-α-hydroxylase enzyme. Calcitriol, through the downregulation mechanism of renin expression, renin-angiotensin-aldosterone system (RAAS) activity, and its interaction with the vitamin D receptor, can bring CV benefits. The calcitriol form also lowers parathyroid hormone (PTH) levels by indirectly causing a reduction in aldosterone and mineralocorticoid synthesis. Elevated plasma aldosterone is related to endothelial dysfunction and CVD in hypovitaminosis D status. CONCLUSION: Vitamin D supplementation may benefit certain risk groups, as it improves metabolic variables, reducing oxidative stress and CV outcomes. More studies are needed to define interventions with vitamin D in men and women.

Improving vitamin D content in pork meat by UVB biofortification.

Vitamin D deficiency is prevalent worldwide and identification of alternative food-based strategies are urgently warranted. In two studies, 12-week old crossbred pigs (Duroc x (Large White x Landrace)) were exposed daily to narrowband UVB radiation for ∼10 weeks or control (no UVB exposure) until slaughter. In Study 1 (n = 48), pigs were exposed to UVB for 2 min and in Study 2 (n = 20), this duration was tripled to 6 min. All pigs were fed the maximum permitted 2000 IU vitamin D3/kg feed. Loin meat was cooked prior to vitamin D LC-MS/MS analysis. In Study 1, pork loin vitamin D3 did not differ between groups. Study 2 provided longer UVB exposure time and resulted in significantly higher loin vitamin D3 (11.97 vs. 6.03 µg/kg), 25(OH)D3 (2.09 vs. 1.65 µg/kg) and total vitamin D activity (22.88 vs. 14.50 µg/kg) concentrations, compared to control (P < 0.05). Pigs remained healthy during both studies and developed no signs of erythema. Biofortification by UVB radiation provides an effective strategy to further safely increase the naturally occurring vitamin D content of pork loin, alongside feed supplementation.

The future is bright: Biofortification of common foods can improve vitamin D status.

Vitamin D deficiency is a global concern, linked to suboptimal musculoskeletal health and immune function, with status inadequacies owing to variations in UV dependent cutaneous synthesis and limited natural dietary sources. Endogenous biofortification, alongside traditional fortification and supplement usage is urgently needed to address this deficit. Evidence reviewed in the current article clearly demonstrates that feed modification and UV radiation, either independently or used in combination, effectively increases vitamin D content of primary produce or ingredients, albeit in the limited range of food vehicles tested to date (beef/pork/chicken/eggs/fish/bread/mushrooms). Fewer human trials have confirmed that consumption of these biofortified foods can increase circulating 25-hydroxyvitamin D [25(OH)D] concentrations (n = 10), which is of particular importance to avoid vitamin D status declining to nadir during wintertime. Meat is an unexplored yet plausible food vehicle for vitamin D biofortification, owing, at least in part, to its ubiquitous consumption pattern. Consumption of PUFA-enriched meat in human trials demonstrates efficacy (n = 4), lighting the way for exploration of vitamin D-biofortified meats to enhance consumer vitamin D status. Response to vitamin D-biofortified foods varies by food matrix, with vitamin D3-enriched animal-based foods observing the greatest effect in maintaining or elevating 25(OH)D concentrations. Generally, the efficacy of biofortification appears to vary dependent upon vitamer selected for animal feed supplementation (vitamin D2 or D3, or 25(OH)D), baseline participant status and the bioaccessibility from the food matrix. Further research in the form of robust human clinical trials are required to explore the contribution of biofortified foods to vitamin D status.

Vitamin D concentrations and breast cancer incidence among Black/African American and non-Black Hispanic/Latina women.

BACKGROUND: Vitamin D may protect against breast cancer. Although Black/African American women and Hispanic/Latina women have lower circulating vitamin D levels than non-Hispanic White women, few studies have examined the association between vitamin D and breast cancer within these racial/ethnic groups. METHODS: The vitamin D-breast cancer association was evaluated using a case-cohort sample of self-identified Black/African American and non-Black Hispanic/Latina women participating in the US-wide Sister Study cohort. Circulating 25-hydroxyvitamin D (25(OH)D) and 24,25-dihydroxyvitamin D (24,25(OH)2D) were measured using liquid chromatography-tandem mass spectrometry in blood samples collected at the baseline from 415 women (290 Black/African American women and 125 non-Black Hispanic/Latina women) who developed breast cancer. These were compared to concentrations in 1545 women (1084 Black/African American women and 461 Hispanic/Latina women) randomly selected from the cohort. Multivariable-adjusted Cox regression was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs). RESULTS: Over a mean follow-up of 9.2 years, women with circulating 25(OH)D concentrations above the clinical cut point for deficiency (20.0 ng/mL) had lower breast cancer rates than women with concentrations ≤ 20 ng/mL (HR, 0.79; 95% CI, 0.61-1.02). The inverse association was strongest among Hispanic/Latina women (HR, 0.52; 95% CI, 0.29-0.93), with a weaker association observed among Black/African American women (HR, 0.89; 95% CI, 0.68-1.18; P for heterogeneity = 0.13). There were no clear differences by menopausal status, follow-up time, estrogen receptor status, or invasiveness. Neither 24,25(OH)2 D nor the 24,25(OH)2 D to 25(OH)D ratio were independently associated with breast cancer risk. CONCLUSIONS: This prospective study supports the hypothesis that vitamin D may be protective against breast cancer incidence in women, including non-Black Hispanic/Latina and Black/African American women. LAY SUMMARY: Vitamin D may protect against breast cancer. Although women of color have lower average vitamin D levels than non-Hispanic White women, few studies have considered the role of race/ethnicity. In a sample of self-identified Black/African American and Hispanic/Latina women, we observed that vitamin D concentrations measured in blood were inversely associated with breast cancer, particularly among Latinas. These findings indicate that vitamin D may protect women against breast cancer, including those in racial/ethnic groups with low average circulating levels.

25-hydroxyvitamin D levels are inversely related to metabolic syndrome risk profile in northern Chinese subjects without vitamin D supplementation.

BACKGROUND: The comparatively low 25 hydroxyvitamin D [25(OH)D] levels have been reported in patients with metabolic syndrome (MetS). Herein we investigated the cross-sectional and longitudinal relationships between serum 25(OH)D levels and MetS risk profile in northern middle-aged Chinese subjects without vitamin D supplementation. METHODS: A cohort of 211 participants including 151 MetS patients and 60 controls at 20-69 years of age were enrolled from suburban Beijing, China. The recruited MetS patients were subjected to diet and exercise counselling for 1-year. All subjects at baseline and MetS patients after intervention underwent clinical evaluations. RESULTS: Serum 25(OH)D levels were significantly decreased in MetS patients. 25(OH)D levels were inversely related to MetS score, fasting blood glucose (FBG) and triglyceride-glucose index (TyG) after adjusting for cofounders (all P < 0.05). Participants in the lowest tertile of 25(OH)D levels had increased odds for MetS (P = 0.045), elevated FBG (P = 0.004) in all subjects, and one MetS score gain in MetS patients (P = 0.005). Longitudinally, the metabolic statuses as well as 25(OH)D levels of MetS patients were significantly improved (all P < 0.05), and the increase of 25(OH)D levels were inversely related to MetS scores, total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), FBG, and TyG, while positively related to high-density lipoprotein cholesterol (HDL-C) after adjusting for confounders. CONCLUSIONS: 25(OH)D levels were significantly decreased in MetS patients, and it was negatively associated with metabolic dysfunctions at baseline and 1-year after. Metabolic aberrations of MetS patients were significantly ameliorated with 1-year follow-up counselling accompanying by notably elevated 25(OH)D levels.

Interlaboratory comparison of 25-hydroxyvitamin D assays: Vitamin D Standardization Program (VDSP) Intercomparison Study 2 - Part 1 liquid chromatography - tandem mass spectrometry (LC-MS/MS) assays - impact of 3-epi-25-hydroxyvitamin D3 on assay performance.

An interlaboratory comparison study was conducted by the Vitamin D Standardization Program (VDSP) to assess the performance of liquid chromatography - tandem mass spectrometry (LC-MS/MS) assays used for the determination of serum total 25-hydroxyvitamin D (25(OH)D), which is the sum of 25-hydroxyvitamin D2 (25(OH)D2) and 25-hydroxyvitamin D3 (25(OH)D3). A set of 50 single-donor samples was assigned target values for concentrations of 25(OH)D2, 25(OH)D3, 3-epi-25-hydroxyvitamin D3 (3-epi-25(OH)D3), and 24R,25-dihydroxyvitamin D3 (24R,25(OH)2D3) using isotope dilution liquid chromatography - tandem mass spectrometry (ID LC-MS/MS). VDSP Intercomparison Study 2 Part 1 includes results from 14 laboratories using 14 custom LC-MS/MS assays. Assay performance was evaluated using mean % bias compared to the assigned target values and using linear regression analysis of the test assay mean results and the target values. Only 53% of the LC-MS/MS assays met the VDSP criterion of mean % bias ≤ |±5%|. For the LC-MS/MS assays not meeting the ≤ |±5%| criterion, four assays had mean % bias of between 12 and 21%. Based on multivariable regression analysis using the concentrations of the four individual vitamin D metabolites in the 50 single-donor samples, the performance of several LC-MS/MS assays was found to be influenced by the presence of 3-epi-25(OH)D3. The results of this interlaboratory study represent the most comprehensive comparison of LC-MS/MS assay performance for serum total 25(OH)D and document the significant impact of the lack of separation of 3-epi-25(OH)D3 and 25(OH)D3 on assay performance, particularly with regard to mean % bias.

Interlaboratory comparison of 25-hydroxyvitamin D assays: Vitamin D Standardization Program (VDSP) Intercomparison Study 2 - Part 2 ligand binding assays - impact of 25-hydroxyvitamin D2 and 24R,25-dihydroxyvitamin D3 on assay performance.

An interlaboratory comparison study was conducted by the Vitamin D Standardization Program (VDSP) to assess the performance of ligand binding assays (Part 2) for the determination of serum total 25-hydroxyvitamin D [25(OH)D]. Fifty single-donor samples were assigned target values for concentrations of 25-hydroxyvitamin D2 [25(OH)D2], 25-hydroxyvitamin D3 [25(OH)D3], 3-epi-25-hydroxyvitamin D3 [3-epi-25(OH)D3], and 24R,25-dihydroxyvitamin D3 [24R,25(OH)2D3] using isotope dilution liquid chromatography-tandem mass spectrometry (ID LC-MS/MS). VDSP Intercomparison Study 2 Part 2 includes results from 17 laboratories using 32 ligand binding assays. Assay performance was evaluated using mean % bias compared to the assigned target values and using linear regression analysis of the test assay mean results and the target values. Only 50% of the ligand binding assays achieved the VDSP criterion of mean % bias ≤ |± 5%|. For the 13 unique ligand binding assays evaluated in this study, only 4 assays were consistently within ± 5% mean bias and 4 assays were consistently outside ± 5% mean bias regardless of the laboratory performing the assay. Based on multivariable regression analysis using the concentrations of individual vitamin D metabolites in the 50 single-donor samples, most assays underestimate 25(OH)D2 and several assays (Abbott, bioMérieux, DiaSorin, IDS-EIA, and IDS-iSYS) may have cross-reactivity from 24R,25(OH)2D3. The results of this interlaboratory study represent the most comprehensive comparison of 25(OH)D ligand binding assays published to date and is the only study to assess the impact of 24R,25(OH)2D3 content using results from a reference measurement procedure.

Vitamin D Biofortification of Pork May Offer a Food-Based Strategy to Increase Vitamin D Intakes in the UK Population.

Hypovitaminosis D is prevalent worldwide, with many populations failing to achieve the recommended nutrient intake (RNI) for vitamin D (10-20 µg/day). Owing to low vitamin D intakes, limited exposure to ultraviolet-B (UVB) induced dermal synthesis, lack of mandatory fortification and poor uptake in supplement advice, additional food-based strategies are warranted to enable the UK population to achieve optimal vitamin D intakes, thus reducing musculoskeletal risks or suboptimal immune functioning. The aims of the current study were to (1) determine any changes to vitamin D intake and status over a 9-year period, and (2) apply dietary modeling to predict the impact of vitamin D biofortification of pork and pork products on population intakes. Data from the UK National Diet and Nutrition Survey (Year 1-9; 2008/09-2016/17) were analyzed to explore nationally representative mean vitamin D intakes and 25-hydroxyvitamin D (25(OH)D) concentrations (n = 13,350). Four theoretical dietary scenarios of vitamin D pork biofortification were computed (vitamin D content +50/100/150/200% vs. standard). Vitamin D intake in the UK population has not changed significantly from 2008 to 2017 and in 2016/17, across all age groups, 13.2% were considered deficient [25(OH)D <25 nmol/L]. Theoretically, increasing vitamin D concentrations in biofortified pork by 50, 100, 150, and 200%, would increase vitamin population D intake by 4.9, 10.1, 15.0, and 19.8% respectively. When specifically considering the impact on gender and age, based on the last scenario, a greater relative change was observed in males (22.6%) vs. females (17.8%). The greatest relative change was observed amongst 11-18 year olds (25.2%). Vitamin D intakes have remained stable in the UK for almost a decade, confirming that strategies are urgently required to help the population achieve the RNI for vitamin D. Biofortification of pork meat provides a proof of concept, demonstrating that animal-based strategies may offer an important contribution to help to improve the vitamin D intakes of the UK population, particularly adolescents.

Serum 25-hydroxy vitamin D level is associated with cognitive impairment in people aged 65 years and older.

BACKGROUND: Vitamin D deficiency is prevalent in the population, especially in older people. In recent years, studies have revealed an association between a low vitamin D level and cognitive decline. The present research aimed to investigate the relationship of serum 25-hydroxyvitamin D (25-OH-D) level with cognitive function in senior patients. METHODS: We recruited 299 patients aged 65 years and older. The patients were grouped based on their serum 25-OH-D levels into group A (<10.0 ng/mL), B (10.0-19.9 ng/mL), and C (≥20.0 ng/mL). Cognitive function was assessed with the Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Clinical Dementia Rating (CDR) scale, and Activities of Daily Living (ADL) scale. RESULTS: MMSE and MoCA scores were significantly lower in group A (26.02±3.99 and 21.56±5.59, respectively) than in group B (27.34±2.79 and 23.94±4.74, respectively) and group C (27.65±2.54 and 24.95±4.45, respectively). The proportion of patients with cognitive impairment was increased in group A (71.1%) compared to group B (55.3%) and group C (43.9%), and the difference was statistically significant (both P<0.01). Spearman's correlation analysis showed that MMSE and MoCA had a positive relationship with serum 25-OH-D level (ß=0.173 and 0.243, both P<0.01) with adjustments for factors as age, sex, and education level. Stepwise regression analysis indicated that MMSE and MoCA scores were correlated with serum 25-OH-D level, age, and education level. CONCLUSIONS: A lower level of 25-OH-D is common in senior patients and is associated with cognitive impairment. Patients with severe deficiency of vitamin D (serum 25-OH-D level <10 ng/mL) have lower MMSE and MoCA scores and a higher risk of cognitive dysfunction.

Low prevalence of vitamin D deficiency in adult residents in Hainan, the tropical island province of China.

BACKGROUND: Vitamin D deficiency is considered to be a global health problem. The purpose of this study was to evaluate the prevalence of vitamin D deficiency and analyze its related factors among adult residents in Hainan, a tropical island province of southern China. METHODS: A total of 1,700 healthy adults, aged 18-86 years (617 men and 1,073 women), were enrolled in our cross-sectional descriptive study. Binomial logistic regression analyses were performed to identify possible predictors of vitamin D status. RESULTS: The average serum 25-hydroxyvitamin D [25(OH)D] concentration was 37.66±10.77 ng/mL (males 43.60±11.8 ng/mL, females 34.20±8.40 ng/mL; I<0.001). The proportions of vitamin D sufficiency [25(OH)D ≥30 ng/mL], insufficiency [20 ng/mL ≤25(OH)D <30 ng/mL], and deficiency [25(OH)D <20 ng/mL] were 76.6%, 20.5%, and 2.9%, respectively. Vitamin D deficiency in the young, middle-aged, and elderly groups were 4.2%, 2.7%, and 1.7%, respectively. Vitamin D sufficiency was found to be positively associated with male sex (P<0.0001), age >40 years (P=0.014), habitation in a rural area (P<0.0001), summer/autumn seasons (P<0.0001), and having <13 years of formal education (P<0.0001). CONCLUSIONS: Our study was the first to assess the vitamin D status and analyze related factors among adult residents in Hainan Province, China. We found that vitamin D deficiency has low prevalence in this population, suggesting that before developing a strategy for the clinical use of vitamin D supplements in a region, the levels of vitamin D in generally healthy populations of that region should be assessed, to avoid unnecessary supplementation.

Non-Musculoskeletal Benefits of Vitamin D beyond the Musculoskeletal System.

Vitamin D, a fat-soluble prohormone, is endogenously synthesized in response to sunlight or taken from dietary supplements. Since vitamin D receptors are present in most tissues and cells in the body, the mounting understanding of the role of vitamin D in humans indicates that it does not only play an important role in the musculoskeletal system, but has beneficial effects elsewhere as well. This review summarizes the metabolism of vitamin D, the research regarding the possible risk factors leading to vitamin D deficiency, and the relationships between vitamin D deficiency and numerous illnesses, including rickets, osteoporosis and osteomalacia, muscle weakness and falls, autoimmune disorders, infectious diseases, cardiovascular diseases (CVDs), cancers, and neurological disorders. The system-wide effects of vitamin D and the mechanisms of the diseases are also discussed. Although accumulating evidence supports associations of vitamin D deficiency with physical and mental disorders and beneficial effects of vitamin D with health maintenance and disease prevention, there continue to be controversies over the beneficial effects of vitamin D. Thus, more well-designed and statistically powered trials are required to enable the assessment of vitamin D's role in optimizing health and preventing disease.