National Estimates of Serum Total 25-Hydroxyvitamin D and Metabolite Concentrations Measured by Liquid Chromatography-Tandem Mass Spectrometry in the US Population during 2007-2010

Vitamin D beyond the blood: Tissue distribution of vitamin D metabolites after supplementation

Vitamin D3's role in mineral homeostasis through its endocrine function, associated with the main circulating metabolite 25-hydroxyvitamin D3, is well characterized. However, the increasing recognition of vitamin D3's paracrine and autocrine functions-such as cell growth, immune function, and hormone regulation-necessitates examining vitamin D3 levels across different tissues post-supplementation. Hence, this review explores the biodistribution of vitamin D3 in blood and key tissues following oral supplementation in humans and animal models, highlighting the biologically active metabolite, 1,25-dihydroxyvitamin D3, and the primary clearance metabolite, 24,25-dihydroxyvitamin D3. While our findings indicate significant progress in understanding how circulating metabolite levels respond to supplementation, comprehensive insight into their tissue concentrations remains limited. The gap is particularly significant during pregnancy, a period of drastically increased vitamin D3 needs and metabolic alterations, where data remains sparse. Within the examined dosage ranges, both human and animal studies indicate that vitamin D3 and its metabolites are retained in tissues selectively. Notably, vitamin D3 concentrations in tissues show greater variability in response to administered doses. In contrast, its metabolites maintain a more consistent concentration range, albeit different among tissues, reflecting their tighter regulatory mechanisms following supplementation. These observations suggest that serum 25-hydroxyvitamin D3 levels may not adequately reflect vitamin D3 and its metabolite concentrations in different tissues. Therefore, future research should aim to generate robust human data on the tissue distribution of vitamin D3 and its principal metabolites post-supplementation. Relating this data to clinically appropriate exposure metrics will enhance our understanding of vitamin D3's cellular effects and guide refinement of clinical trial methodologies.

High ratio of epi-25-(OH)-vitamin D3 to 25-(OH)-vitamin D3 increases the risk of asthma attack in American asthma adults: a population study

OBJECTIVE

The relationship between vitamin D3 and asthma remains controversial. However, previous studies have largely overlooked the impact of epi-25-(OH)-vitamin D3. This study aims to investigate the effects of different forms of vitamin D3 on asthma attack in adults.

METHODS

In this cross-sectional study, a total of 3,873 eligible adult participants were extracted from the national health and nutrition examination survey (NHANES) database from 2007 to 2018. Based on quartiles method, different levels of vitamin D were divided into four groups (Quartile 1-4). Bivariate correlation analysis was performed for vitamin D and covariates to avoid multicollinearity. Multivariate logistic regression was used to investigate the association between serum levels of vitamin D3 (epi-25-(OH)-vitamin D3 and 25-(OH)-vitamin D3) and asthma attack, adjusting for covariates including age, gender, race, length of time in the U.S., house poverty income ratio (PIR), education level, smoking history, hypertension history, and diabetes history. The ratio of epi-25-(OH)-vitamin D3 to 25-(OH)-vitamin D3 was used for secondary analysis of its association with asthma attack. The outcomes were assessed by odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Among the 3,873 eligible adults American with asthma, 1,508 (38.94%) had experienced at least one acute asthma attack in the past year. There was no significant correlation between vitamin D and covariates. After adjusting for covariates including age, gender, race, length of time in the U.S., house poverty income ratio (PIR), education level, smoking history, hypertension history and diabetes history, we found a positive correlation between the ratio of epi-25-(OH)-vitamin D3 to 25-(OH)-vitamin D3 and asthma attack. Additionally, a high ratio of epi-25-(OH)-vitamin D3 to 25-(OH)-vitamin D3 was more common among elder, male, of normal weight, non-Hispanic American, have a long time stay in the U.S., a high house PIR, and a history of hypertension individuals.

CONCLUSION

Our findings suggest that attention should be given to asthma attack associated with a high ratio of epi-25-(OH)-vitamin D3 to 25-(OH)-vitamin D3 in American adults who are elderly, male, of normal weight, non-Hispanic Americans, have long-term residence in the U.S., a high house PIR, and a history of hypertension.

Differential performance regarding the relationship of C3-epi-25(OH)D3 levels and %C3-epi-25(OH)D3 with common pediatric diseases: a case control study

BACKGROUND

Recently, the C3-epimer of 25-hydroxyvitamin D [C3-epi-25(OH)D] has become a topic of interest among 25-hydroxyvitamin D [25(OH)D] metabolites. Although it can lead to an overestimation of vitamin D storage, its relationship with disease occurrence remains controversial, possibly related to the great extent of tracking of 25(OH)D by C3-epi-25(OH)D over time. This study aimed to investigate the differential performance of C3-epi-25(OH)D3 and its percentage [%C3-epi-25(OH)D3] with respect to 20 common paediatric diseases.

METHODS

This study involved 805 healthy children and adolescents and 2962 patients with common paediatric diseases. We investigated sex, age, and seasonal differences in C3-epi-25(OH)D3 and %C3-epi-25(OH)D3 levels; their variations on 20 common paediatric diseases; and their degree of correlation with 25(OH)D3 levels and various diseases.

RESULTS

Among the healthy underage participants, C3-epi-25(OH)D3 and %C3-epi-25(OH)D3 changed similarly, with no sex differences. Moreover, their levels were higher in the infant period than in the other periods (t = 5.329-5.833, t = 4.640-5.711, all Padj < 0.001), and in spring and summer than in autumn and winter (t = 3.495-6.061, t = 3.495-5.658, all Padj < 0.01). Under healthy and disease conditions, C3-epi-25(OH)D3 was positively correlated with 25(OH)D3 (ρ = 0.318 ~ 0.678, all P < 0.017), whereas %C3-epi-25(OH)D3 was not, except in patients with nephrotic syndrome (ρ=-0.393, P = 0.001). Before and after adjusting for 25(OH)D3, the relationship of C3-epi-25(OH)D3 with the diseases was notably different. However, it was almost consistent for %C3-epi-25(OH)D3. Our results indicated that %C3-epi-25(OH)D3 was associated with short stature, nephrotic syndrome, lymphocytic leukaemia, rickets, paediatric malnutrition, and hypovitaminosis D (OR = 0.80 ~ 1.21, all P < 0.05).

CONCLUSIONS

The %C3-epi-25(OH)D3 can correct the properties of C3-epi-25(OH)D3 to better track 25(OH)D3 and may be more suitable for exploring its pathological relevance. Further detailed studies of each disease should be conducted.

Association between vitamin D, depression, and sleep health in the National Health and Nutrition Examination Surveys: a mediation analysis

OBJECTIVE

This study aimed to assess the association between vitamin D and sleep health and to investigate whether depression could mediate this relationship.

METHODS

A cross-sectional analysis was performed using the 2005-2014 US National Health and Nutrition Examination Survey (NHANES) data. The logistic regression models were conducted to evaluate association of serum vitamin D concentrations with sleep health and depression. Mediation analyses were conducted to investigate the mediated effects of depression on the association of vitamin D with sleep health.

RESULTS

In multivariate logistic models, vitamin D was found to be negatively associated with an increased risk of poor sleep health, with an odds ratio (OR) of vitamin D deficiency versus sufficiency was 1.256 (95% CI = 1.084-1.455). Additionally, univariate logistic models showed that vitamin D was also negatively associated with depression risk (vitamin D deficiency vs. sufficiency: OR = 1.699, 95% CI = (1.373-2.103). Further mediation analyses showed that the association of vitamin D with sleep health was mediated by depression, with the mediating effects of depression accounted for 44.56% of the total effects.

CONCLUSION

Vitamin D affects sleep health directly and indirectly through depression. The results suggest that interventions increasing intake of vitamin D should be prioritized to promote sleep health of persons with or at risk of depression.

Vitamin D and risk of developing type 2 diabetes in the SUN project: a prospective cohort study

PURPOSE

Vitamin D deficiency has been associated with multiple chronic diseases, including metabolic disorders such as insulin resistance and type 2 diabetes (T2D). The aim of the study was to analyze the association between validated predicted serum vitamin D status and the risk of developing T2D in a large prospective cohort based on a Mediterranean population.

METHODS

The SUN project is a prospective and dynamic Spanish cohort that gathers university graduates who have answered lifestyle questionnaires, including a validated Food Frequency Questionnaire. The association between predicted serum vitamin D and the risk of T2D was assessed through Cox regression models according to quartiles (Q) of predicted vitamin D at baseline. The models were adjusted for potential confounders and sensitivity analyses were performed to ensure the robustness of our findings.

RESULTS

Our study included a total of 18,594 participants and after a total follow-up of 238,078 person-years (median follow-up of 13.5 years), 209 individuals were diagnosed with incident T2D. We found a significant inverse association between predicted levels of serum vitamin D and the risk of developing T2D, after adjusting for potential confounders and performing different sensitivity analyses (hazard ratio Q4 vs. Q1: 0.48, 95% CI 0.26-0.88; p for trend = 0.032).

CONCLUSION

The outcomes suggest that higher levels of vitamin D at baseline may be associated with a reduced risk of developing T2D.

Vitamin D deficiency trends, risk factors, and occupational risk in active component service members of the U.S. Armed Forces, 2018-2022

Vitamin D contains 2 related fat-soluble substances, D3 and D2, that are essential for bone health and overall well-being. The burden of vitamin D deficiency within the active component of the armed forces is unknown. This study describes trends of vitamin D deficiency diagnoses in the active component of the U.S. Armed Forces. Risk factors for vitamin D, such as military occupation, were examined to see if preventive measures and targeted vitamin D screening would be beneficial, as the United States Preventive Task Force does not recommend universal screening for vitamin D, nor does TRICARE cover screening for asymptomatic individuals. The surveillance period covered January 1, 2018 through December 31, 2022. The data were derived from the Defense Medical Surveillance System (DMSS). Vitamin D deficiency was measured using ICD-9-CM and ICD-10-CM diagnoses recorded in inpatient and outpatient medical encounters. Incidence rate and average annual prevalence were calculated. A logistic regression was performed to obtain adjusted odds ratios. The rates of vitamin D deficiency diagnoses among active component service members (ACSMs) remained steady during the study period, with an incidence rate of 16.4 per 1,000 person-years and an average annual prevalence of 2.2%. Female service members, those of older age groups, and indoor workers demonstrated higher rates of vitamin D deficiency. Previously described demographic risk factors such as indoor work and history of obesity or malabsorption syndrome were also associated in this study with vitamin D deficiency in ACSMs, although older age groups in this study were not associated with vitamin D deficiency. Pilots and air crew had the lowest rates of vitamin D deficiency, while health care workers had the highest, when evaluating by occupation.

Association of serum 25-hydroxyvitamin D with cardiovascular and all-cause mortality in patients with chronic kidney disease: NHANES 2007‒2018 results

BACKGROUND

Vitamin D insufficiency is a prevalent issue in patients suffering from CKD. The purpose of this study was to determine whether serum 25(OH)D levels are associated with all-cause and cardiovascular mortality in patients with CKD.

METHODS

To examine the associations between 25(OH)D levels and cardiovascular mortality, this retrospective cohort study used the National Health and Nutrition Examination Survey (NHANES) and the National Death Index (NDI) 2007‒2018 database. A total of 2,668 eligible subjects were included in this study, with follow-up conducted until December 31, 2019. The associations were assessed using Cox proportional hazards regression, restricted cubic splines, Kaplan-Meier survival curves, and competing risks survival analysis. Furthermore, subgroup and sensitivity analyses were performed.

RESULTS

During a median follow-up of 72 months in a weighted population of 11,715,452 eligible participants, there were 665 deaths from any cause, including 196 cardiovascular-related deaths. After adjusting for covariates, lower levels of 25(OH)D were significantly associated with increased risks for both all-cause mortality (HR= 0.85, 95 % CI 0.77∼0.94) and cardiovascular mortality (SHR= 0.80, 95 % CI 0.67∼0.94). Consistent results were also observed when analyzing 25(OH)D as a categorical variable (quartile). Compared to group Q1, both group Q3 (HR = 0.71, 95 % CI 0.54‒0.93) and group Q4 (HR = 0.72, 95 % CI 0.55‒0.94) exhibited a significantly reduced mortality risk. Weighted restricted cubic splines revealed an inverse J-shaped linear association between levels of 25(OH) D and all-cause mortality ((PNonliner > 0.05). Subgroup analysis and sensitivity analysis yielded similar findings.

CONCLUSIONS

All-cause mortality and cardiovascular disease-related mortality were significantly increased by lower 25(OH)D levels, both as continuous and categorical variables. 25(OH)D has an inverse J-shaped linear association with all-cause and cardiovascular mortality.

Structural diversification of vitamin D using microbial biotransformations

Vitamin D deficiencies are linked to multiple human diseases. Optimizing its synthesis, physicochemical properties, and delivery systems while minimizing side effects is of clinical relevance and is of great medical and industrial interest. Biotechnological techniques may render new modified forms of vitamin D that may exhibit improved absorption, stability, or targeted physiological effects. Novel modified vitamin D derivatives hold promise for developing future therapeutic approaches and addressing specific health concerns related to vitamin D deficiency or impaired metabolism, such as avoiding hypercalcemic effects. Identifying and engineering key enzymes and biosynthetic pathways involved, as well as developing efficient cultures, are therefore of outmost importance and subject of intense research. Moreover, we elaborate on the critical role that microbial bioconversions might play in the a la carte design, synthesis, and production of novel, more efficient, and safer forms of vitamin D and its analogs. In summary, the novelty of this work resides in the detailed description of the physiological, medical, biochemical, and epidemiological aspects of vitamin D supplementation and the steps towards the enhanced and simplified industrial production of this family of bioactives relying on microbial enzymes. KEY POINTS: • Liver or kidney pathologies may hamper vitamin D biosynthesis • Actinomycetes are able to carry out 1α- or 25-hydroxylation on vitamin D precursors.

Serum Vitamin D and Vaspin Levels Among Patients with Acute Myocardial Infarction and Their Association with Risk Factors

Purpose

The current study investigated and compared serum levels of vitamin D (VD) and vaspin in AMI patients and healthy subjects and correlated these biomarkers with other biochemical risk factors for AMI.

Patients and Methods

The research was carried out at King Abdulaziz University Hospital (KAUH) in Jeddah. Blood samples and additional information were gathered from 110 admitted AMI patients in the Intensive Coronary Care Unit (ICCU) (ages 40-65 years) and 50 adult, healthy volunteers whose BMI and age were similar to those of the patients.

Results

AMI patients had significantly lower vaspin (p < 0.001) and VD levels (p < 0.001) than the control group. Fasting plasma glucose (FPG), hemoglobin A1C (HbA1c), triglycerides (TG), high-density lipoprotein cholesterol (HDL-C), and low-density lipoprotein cholesterol (LDL-C) levels were shown to be significantly different between AMI patients and controls. Among the AMI patients, 15 (13.6%) had deficient serum VD levels (≤20 ng/mL), 60 (54.5%) had insufficient levels (>20 - <30 ng/mL), and 35 (31.8%) had sufficient levels (≥30 ng/mL). In healthy subjects, VD levels were deficient in 4(8%), insufficient in 13 (26%), and sufficient in 33 (66%). VD insufficiency was more prevalent in AMI patients compared to the healthy group (54.5% vs 26%; p < 0.001). In AMI patients, serum vaspin was found to be related to age and HbA1c in the control group. VD did not show a significant correlation with any variable in AMI patients and healthy subjects. Serum vaspin (p = 0.89) and VD levels (p = 0.29) did not differ significantly between female and male control groups.

Conclusion

Compared to the healthy group, AMI patients showed significantly lower vaspin and VD levels. Additionally, AMI patients had a higher prevalence of VD deficiency and insufficiency, suggesting its possible role in the occurrence of AMI.

Effect of Daily Vitamin D Supplementation on Risk of Upper Respiratory Infection in Older Adults: A Randomized Controlled Trial

BACKGROUND

Among individuals with vitamin D deficiency, daily vitamin D supplementation appears to lower risk of acute respiratory infection. However, recent trials, in different populations and using different regimens, have yielded null results. We investigated the effect of daily vitamin D supplementation (vs placebo) on risk of upper respiratory infection (URI) in older adults.

METHODS

The VITamin D and OmegA-3 TriaL (VITAL) is a randomized, double-blind, placebo-controlled trial of supplemental vitamin D and/or omega-3 fatty acids in generally healthy men (age ≥50 years) and women (age ≥55 years). This prespecified analysis focuses on vitamin D3 (2000 IU/day) versus placebo in the 15 804 (61%) participants with baseline serum total 25-hydroxyvitamin D level. The primary outcome was self-report of a recent URI at 1-year follow-up.

RESULTS

Participants had a mean age of 68 years and 51% were women; 76% were non-Hispanic White, 16% Black, and 8% other race/ethnicity. The mean 25-hydroxyvitamin D level at baseline was 31 (standard deviation, 10) ng/mL, with <12 ng/mL in 2.4%. The overall effect of vitamin D supplementation on recent URI was nonsignificant (odds ratio [OR], 0.96 [95% confidence interval {CI}, .86-1.06]). In the prespecified subgroup of primary interest (<12 ng/mL and denied taking concurrent vitamin D), which had only 255 participants, vitamin D supplementation was nonsignificant (OR, 0.60 [95% CI, .28-1.30]). Statistical power to assess effect modification in other subgroups was limited.

CONCLUSIONS

In older adults not selected for vitamin D deficiency, supplemental vitamin D did not lower URI risk overall. Whether effects differ in subgroups requires further study. Clinical Trials Registration. NCT01169259.

Evolution and impact of Standard Reference Materials (SRMs) for determining vitamin D metabolites

The National Institute of Standards and Technology (NIST), in collaboration with the National Institutes of Health, Office of Dietary Supplements (NIH ODS), introduced the first Standard Reference Material® (SRM) for determining vitamin D metabolites in 2009 motivated by significant concerns about the comparability and accuracy of different assays to assess vitamin D status. After 14 years, a suite of five serum matrix SRMs and three calibration solution SRMs are available. Values were also assigned for vitamin D metabolites in five additional SRMs intended primarily to support measurements of other clinical diagnostic markers. Both the SRMs and the certification approach have evolved from significant exogenous serum content to primarily endogenous content and from value assignment by combining the results of multiple analytical methods to the use of measurements exclusively from reference measurement procedures (RMPs). The impact of the availability of these SRMs can be assessed by both the distribution information (sales) and by reports in the scientific literature describing their use for method validation, quality control, and research. In this review, we describe the development of these SRMs, the evolution in design and value assignment, the expansion of information reported, and SRM use in validating analytical methods and providing quality assurance within the vitamin D measurement community.

Association between vitamin D deficiency and post-acute outcomes of SARS-CoV-2 infection

OBJECTIVES

This study aimed to investigate the association between vitamin D deficiency (VDD) and post-acute outcomes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection.

METHODS

This retrospective study used the TriNetX research network to identify COVID-19 patients between January 1 and November 30, 2022. Patients were matched using propensity score matching (PSM) and divided into VDD (< 20 ng/mL) and control (≥ 20 ng/mL) groups. The primary outcome was a composite of post-COVID-19 condition (identified by ICD-10 code), all-cause emergency department (ED) visits, hospitalization, and death during the follow-up period (90-180 days) after the diagnosis of COVID-19.

RESULTS

From an initial recruitment of 42,674 non-hospitalized patients with COVID-19 and known 25(OH)D status, a VDD group of 8300 was identified and propensity matched with 8300 controls. During the follow-up period, the VDD group had a higher risk of the primary outcome than did the control group [hazard ratio (HR) = 1.122; 95% confidence interval (CI) = 1.041-1.210]. The VDD group also had a higher risk of all-cause ED visits (HR = 1.114; 95% CI = 1.012-1.226), all-cause hospitalization (HR = 1.230; 95% CI = 1.105-1.369), and all-cause death (HR = 1.748; 95% CI = 1.047-2.290) but not post-COVID-19 condition (HR = 0.980; 95% CI = 0.630-1.523), individually.

CONCLUSION

Among the COVID-19 patients, VDD might be associated with a higher risk of all-cause ED visits, hospitalization, and death during the post-acute phase.

Vitamin D Status and Reference Intervals Measured by Liquid Chromatography-Tandem Mass Spectrometry for the Early Adulthood to Geriatric Ages in a South Korean Population during 2017-2022

This study aimed to describe the latest 25-hydroxyvitamin D (25(OH)D) status of the South Korean population aged ≥ 20 years using 25(OH)D concentrations measured by liquid chromatography-tandem mass spectrometry and to determine the factors associated with total 25(OH)D concentrations. This cross-sectional, retrospective study consecutively selected 119,335 subjects with a median age of 57 (20-101) years who underwent health checkups among 13 Korean cities during 2017-2022. The total 25(OH)D concentration was 54.5 ± 24.0 nmol/L (mean ± SD). The 7.6%, 47.5%, and 82.9% of participants had 25(OH)D less than 25, 50, and 75 nmol/L, respectively. The prevalence of 25(OH)D deficiency (<25 nmol/L) was higher in females than in males (8.9% vs. 6.1%) and varied between age groups, decreasing in older subjects. Those aged 20-29 years had the highest prevalence of 25(OH)D deficiency (23.0% in females and 20.1% in males), which also varied between cities. In the adjusted model, female sex, older age, summer and autumn seasons, lower body mass index (<25 kg/m2), and lower high-sensitivity C-reactive protein concentration (<1 mg/L) were associated with higher total 25(OH)D concentrations. This study could provide an exact understanding of the status of vitamin D and help devise strategies to prevent vitamin D deficiency among the Korean population.

Food security and diet quality, not vitamin D status are significantly associated with depression: Results from NHANES 2015-2018

BACKGROUND

Observational research has suggested a link between vitamin D insufficiency and depression, while evidence from randomized trials examining the association have yielded inconsistent results. Food security and diet quality are also associated with both vitamin D insufficiency and depression. However, the potential interactions between these factors have not been well described.

METHODS

In order to examine the associations between depression, vitamin D status, food security, and diet quality, data from 8988 US adults (≥20 years) in NHANES (National Health and Nutrition Examination Surveys) 2015-2018 were analyzed. Questionnaire-assessed depression, food security, and diet quality and laboratory-analyzed serum vitamin D were used.

RESULTS

Lack of full food security and a 10-point decrease in Healthy Eating Index 2015 score were independently associated with higher risk of mild to severe depression (OR 3.72 and 1.20, respectively, p < 0.001). The association between insufficient serum vitamin D (<75 nmol/L) and depression was fully attenuated after adjusting for food security and diet quality (p = 0.41).

LIMITATIONS

A major limitation of this paper, like all analyses of NHANES, is the inability to establish the temporality of the relationships between food security and diet quality with depression.

CONCLUSIONS

Food security and diet quality, but not vitamin D status, were significantly associated with depression. This highlights how evaluating food security and diet quality are critical in research and public health interventions related to depression. Future interventions, especially into vitamin D insufficiency, as well as health policies should assess and address these factors.

C3-epi-25(OH)D3 percentage, not level, may be a potential biomarker to reflect its pathological increase in multiple diseases: a cross-sectional case-control study

National surveys in developed countries have examined the presence of C3-epimer of 25-hydroxyvitamin D3 [C3-epi-25(OH)D3]. However, controversy remains regarding its association with disease occurrence due to its high correlation with 25-hydroxyvitamin D3 [25(OH)D3]. This study aims to investigate whether %C3-epi-25(OH)D3 can serve as an indicator for this relationship with various diseases. A total of 3086 healthy participants and 4120 patients were included in this study. We investigated the association between C3-epi-25(OH)D3 and %C3-epi-25(OH)D3 levels with gender, age, and season; compared the performance of C3-epi-25(OH)D3 and %C3-epi-25(OH)D3 across different disease conditions; and explored the correlation between %C3-epi-25(OH)D3 and various diseases. Results indicated that C3-epi-25(OH)D3 varied significantly by gender, age, and season (z/χ2 = 3.765, 10.163, and 150.975, all P < 0.01), while only season for %C3-epi-25(OH)D3 (χ2 = 233.098, P < 0.001). In contrast to the significant decrease in C3-epi-25(OH)D3, %C3-epi-25(OH)D3 showed a significant increase in 8 out of 11 disease categories (z = 3.464 ~ 11.543, all Padj < 0.05). Similar opposite changes were also observed in most of the investigated 32 specific diseases. Moreover, an elevation in %C3-epi-25(OH)D3 was found to be significantly associated with 29 specific diseases both in univariate analysis (OR = 1.16 ~ 2.10, all P < 0.05) and after adjusting for gender, age, and season (OR = 1.15 ~ 1.50, all P < 0.05). However, after further adjustment for 25(OH)D3 levels, the association remained significant only for 15 specific diseases (OR = 1.11 ~ 1.50, all P < 0.05). Seasonal stratification analysis further supports the consistent association of %C3-epi-25(OH)D3 with disease across all or nearly all four seasons. In conclusion, %C3-epi-25(OH)D3 may better reflect the production of C3-epi-25(OH)D3 in disease conditions, thereby offering a more applicable approach to investigate its association with diseases. However, the interpretation of this relationship may be confounded by 25(OH)D3 as a potential covariate.

Association between serum 25-hydroxyvitamin D and antimüllerian hormone levels in a cohort of African-American women

OBJECTIVE

To examine the association between serum 25-hydroxyvitamin D [25(OH)D] levels and ovarian reserve as measured using antimüllerian hormone (AMH) levels.

DESIGN

Cross-sectional study.

SETTING

Detroit, Michigan area.

PATIENTS

Data were obtained from a prospective cohort of self-identified Black or African American women aged 23-35 years at the time of enrollment (N = 1,593), who had no prior diagnosis of polycystic ovary syndrome, were not currently pregnant, and were not missing AMH or 25(OH)D level measures.

INTERVENTION

Serum 25(OH)D.

MAIN OUTCOME MEASURE(S)

The serum AMH level was the main outcome. Linear regression was used to examine the associations between categorical 25(OH)D levels (<12, 12-<20, 20-<30, and ≥30 ng/mL) and continuous natural log-transformed AMH levels. Associations between 25(OH)D and high (upper 10th percentile: >7.8 ng/mL) or low AMH (<0.7 ng/mL) levels were estimated with logistic regression. Models were adjusted for age, age-squared, body mass index (kg/m2), hormonal contraceptive use, smoking, and exercise.

RESULTS

The 25(OH)D levels were low; 70% of participants were below 20 ng/mL. In fully adjusted models, compared with 25(OH)D levels <12 ng/mL, those with 25(OH)D levels of 12-<20, 20-<30, and ≥30 ng/mL had an AMH level that was 7% (95% confidence interval [CI]: -4, 20), 7% {95% CI: -6, 22}, or 11% {95% CI: -7, 34} higher, respectively. Moreover, these groups had lower odds of having low AMH levels (odds ratio [95% CI]: 0.63 {0.40, 0.99}, 0.60 {0.34, 1.07}, and 0.76 {0.35, 1.65}, respectively), and the highest category of 25(OH)D levels had higher odds of having high AMH levels (odds ratio [95% CI]: 1.42 {0.74, 2.72}). Exclusion of participants with either irregular cycles or very high AMH (>25 ng/mL) levels did not alter the associations.

CONCLUSION

Taken together, these results indicate that higher levels of 25(OH)D are associated with slightly higher AMH levels, lower odds of low AMH levels, and higher odds of high AMH levels. This evidence is weak, however, because only a small percentage of participants had high 25(OH)D levels. Future studies should examine populations with a wide distribution of 25(OH)D levels (both high and low), with a clinical trial design, or with longitudinal measures of both 25(OH)D and AMH levels.

Longitudinal study of vitamin D status among Thai individuals in a sun-abundant country

Background

Vitamin D deficiency is a major public health problem worldwide, even in countries with abundant sunshine. Understanding the risk factors for vitamin D deficiency is important to inform public health recommendations. We conducted a longitudinal analysis of vitamin D status in Thai individuals to assess changes in vitamin D status over time and identify potential determinants.

Study design

This study is a long term prospective cohort study.

Methods

Of the 1239 participants who were employees of the Electricity Generating Authority of Thailand, serum 25-hydroxyvitamin D (25(OH)D) levels were measured by liquid chromatography/tandem mass spectrometry from samples collected in 2009 and 2019.

Results

There was a significant 14.8% increase in serum total 25(OH)D (P < 0.001) from 2009 to 2019, which resulted from significant increases in both 25(OH)D3 and 25(OH)D2. The epimeric form of 25(OH)D2 also increased significantly, while there was no increase in the epimeric form of 25(OH)D3. A univariate analysis showed significant associations between increased total 25(OH)D and increasing age, male sex, and lower body mass index. After controlling for baseline vitamin D status, multivariate regression analyses found that the direction of association and significance from univariate analyses persisted for total 25(OH)D and 25(OH)D3. However, a univariate association found between female sex and an increase in 25(OH)D2 was not significant in multivariate regression analysis.

Conclusions

A long-term trend of improved vitamin D status was found among Thai adult individuals over a 10-year period; however, improvements were less noticeable in women.

Variation in vitamin D status in infants and children: a two-year cross-sectional study in Shanghai, China

BACKGROUND

Vitamin D deficiency (VDD) is a public health problem. The variation in vitamin D status across regions and populations remains unclear, and there is a lack of consensus regarding the screening for VDD in individuals.

METHODS

Children who visited the hospital from January 2019 to December 2020 were included in this study. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were measured using an enzyme-linked immunosorbent assay. The cutoffs for serum 25(OH)D concentrations to define deficiency, insufficiency, and sufficiency were < 20 ng/mL, 20-30 ng/mL, and ≥ 30 ng/mL, respectively.

RESULTS

A total of 7285 children aged 0-11 years were assessed; the mean 25(OH)D level was 31.4 ng/mL, and the median 25(OH)D level was 30.7 (interquartile range 24.4, 37.5) ng/mL. The 25(OH)D level declined with age in clinical visiting children aged 0-11 years, but maintained a consistently high level in health examination children aged 4-11 years. The percentages of 25(OH)D < 20 ng/mL and 25(OH)D < 30 ng/mL were 10.0% and 43.8%, respectively. Higher percentages of VDD were found in clinical visiting children than in health examination children within the 6-11-year group (53.3% vs. 14.7%) and winter (44.3% vs. 15.4%).

CONCLUSION

Low vitamin D status (deficiency and insufficiency) was more common in clinic-visiting children than in health examinations, especially in schoolchildren and in the winter. The study implies the positive effects of vitamin D assessments included in child health checkups to optimize vitamin D status.

The Impact of Vitamin D Deficiency on Infants' Health

Vitamin D is an essential nutrient that plays a vital role in bone health and musculoskeletal development. The aim of this narrative review is to present up-to-date information about the impact of vitamin D deficiency (VDD) on the health status of infants in their first year of life. Vitamin D is indispensable for skeletal growth and bone health, and emerging research suggests that it may also have significant roles in maternal and fetal health. VDD affects a large proportion of infants according to current guidelines. However, its prevalence varies depending on geographic location, skin pigmentation, and the time of year. Based on current guidelines for normal vitamin D levels and recommended daily intake, studies suggest that VDD is a global health issue with potentially significant implications for those at risk, especially infants. Our understanding of the role of vitamin D has improved significantly in the last few decades. Systematic reviews and meta-analyses investigating the effect of vitamin D on preterm birth, low birth weight, anthropometric parameters, and health outcomes such as infectious diseases in infants, have found conflicting or inconsistent results. It is important to encourage further research to fill in these knowledge gaps and develop national or global strategies that ease the burden of VDD, especially in groups at risk.

Association of serum 25-hydroxyvitamin D levels with all-cause and cause-specific mortality among postmenopausal females: results from NHANES

BACKGROUND

Vitamin D deficiency is common among the population, but its relationship with mortality of postmenopausal females is unclear. The aim of this study is to explore the association between serum 25-Hydroxyvitamin D (25(OH)D) and all-cause and cause-specific mortality among postmenopausal women in the United States.

METHODS

6812 participants of postmenopausal females from the National Health and Nutrition Examination Survey (2001-2018) were included in this study. The mortality status of the follow-up was ascertained by linkage to National Death Index (NDI) records through 31 December 2019. We used cox proportional hazards models to estimate the association of serum 25(OH)D concentrations and mortality of postmenopausal females.

RESULTS

The mean level of serum 25(OH)D was 72.57 ± 29.93 nmol/L, and 65.34% had insufficient vitamin D. In postmenopausal females, low serum 25(OH)D concentrations were significantly associated with higher levels of glycohemoglobin, glucose, and lower levels of HDL. During follow-up, 1448 all-cause deaths occurred, including 393 cardiovascular disease (CVD)-related deaths and 263 cancer deaths. After multivariate adjustment, higher serum 25(OH)D levels were significantly related with lower all-cause and CVD mortality. In addition, serum 25(OH)D presented a L-shaped relationship with all-cause mortality, while appeared a U-shaped with CVD mortality, and the cut-off value is 73.89 nmol/L and 46.75 nmol/L respectively.

CONCLUSIONS

Low serum 25(OH)D levels are associated with the higher risk of all-cause and CVD mortality in postmenopausal females. These findings provide new ideas and targets for the health management of postmenopausal women.

Meta-Analysis of European Clinical Trials Characterizing the Healthy-Adult Serum 25-hydroxyvitamin D Response to Vitamin D Supplementation

To obtain reliable data that allow health authorities to re-evaluate recommendations for oral vitamin D uptake, we conducted a meta-analysis to investigate the impact of supplementation on serum 25-hydroxyvitamin D (25(OH)D) levels in healthy adults in Europe. Of the publications identified (n = 4005) in our literature search (PUBMED, through 2 January 2022), 49 primary studies (7320 subjects, 73 study arms) were eligible for inclusion in our meta-analysis. The risk of bias was assessed using the Cochrane RoB tool based on seven categories, according to which each study is rated using three grades, and overall was rated as rather low. The median duration of intervention was 136.78 days (range, 1088 days); the mean weighted baseline 25(OH)D concentration and mean age were 33.01 vs. 33.84 nmol/L and 46.8 vs. 44.8 years in the vitamin D and placebo groups, respectively. Using random-effects models, 25(OH)D levels were increased by 36.28 nmol/L (95% CI 31.97-40.59) in the vitamin D group compared to the placebo, with a relative serum increment of 1.77 nmol/L per 2.5 μg of vitamin D daily. Notably, the relative serum 25(OH)D increment was affected by various factors, including the dosage and baseline serum 25(OH)D concentration, decreasing with increasing vitamin D doses and with increasing baseline serum levels. We estimate that supplementation in all healthy adults in Europe with appr. 25 μg of vitamin D (1000 IU) daily would raise serum 25(OH)D levels in 95% of the population to ≥50 nmol/L. Our work provides health authorities with reliable data that can help to re-evaluate recommendations for oral vitamin D supplementation.

Vitamin D and Its Metabolites Status before and during Chemotherapy in Caucasian Breast Cancer Patients

BACKGROUND

The predictive role of vitamin D (VD) in breast cancer (BC) patients' survival is still being investigated. This paper aims to evaluate the changes in VD metabolites during chemotherapy (CTH) and the predictive role of VD status in Caucasian BC patients treated with CTH.

METHODS

Vitamin D and its metabolites were assessed with reference LC-MS/MS methodology in 98 consecutive BC patients starting CHT, after 3 and 6 months, and compared to the control group.

RESULTS

The frequency of VD deficiency in BC patients was greater than in the control group (56.1% vs. 37.2%). After 6 months of CTH, the number of VD-deficient BC patients slightly increased to 60%. The concentrations of VD active forms [25(OH)D2, 25(OH)D3], and catabolites [24,25(OH)2D3 and 3-epi-25(OH)D3] decreased after 3 and 6 months of CTH compared to the baseline values. Strong positive correlations between concentrations of 3-epi-25(OH)D3 and 25(OH)D in both groups were found. Similar correlations were also observed between 24,25(OH)2D3 and 25(OH)D levels. Kaplan-Meier survival analysis showed significantly longer survival in BC patients without deficiency (>20 ng/mL) at baseline (HR = 2.44 (95% CI 1.07-5.59), p = 0.026).

CONCLUSIONS

(1) Our data provide further evidence that BC patients before CTH are more VD-deficient than the general population and this deficiency increases further during CTH treatment, as observed using the reference LC-MS methodology. (2) Presented results show that VD catabolism is not affected in BC patients. (3) The poorer survival in VD-deficient BP patients supports the importance of VD supplementation in BC patients with 25(OH)D levels below 20 ng/mL.

The Association Between Vitamin D Levels and the 10-Year Risk of Atherosclerotic Cardiovascular Disease: A Population-Based Study

BACKGROUND

The association between vitamin D levels and atherosclerotic cardiovascular disease (ASCVD) risk remains unclear. In this study, the association between serum 25(OH)D and 10-year ASCVD risk was examined in a national sample of middle-aged and older adults.

METHODS

Cross-sectional data from the 2009-2014 National Health and Nutrition Examination Survey were analyzed. The Pooled Cohort Equations were used to estimate the risk of a first ASCVD event in 10 years. An adjusted multiple linear regression model was used to investigate the association between serum 25(OH)D and ASCVD risk. In addition, we performed sensitivity analysis and interactive analysis to assess the robustness of associations across different subgroups.

RESULTS

A total of 3354 participants were included in this study. The linear regression model indicated that the risk of ASCVD decreased with the increase in serum 25(OH)D. When analyzed as a continuous variable, serum 25(OH)D was significantly associated with the estimated 10-year risk of ASCVD. In the fully adjusted model, each 10-nmol/L increase in serum 25(OH)D reduced the estimated 10-year ASCVD risk by 0.172% ( P < .001). Individuals in the moderate, insufficient, and sufficient vitamin D deficiency groups had a 0.449% ( P = .362), 0.957% ( P = .046), 1.475% ( P = .003) decrease in ASCVD risk, respectively, when a severe vitamin D deficiency group was set as a reference in the fully adjusted model.

CONCLUSION

Our data suggest a negative association between vitamin D levels and the predicted 10-year risk of ASCVD. Further studies are required to investigate whether vitamin D supplements could reduce the risk of ASCVD.

Fortification of Staple Foods for Household Use with Vitamin D: An Overview of Systematic Reviews

Vitamin D deficiency is a global public health concern with significant implications for bone health and chronic disease prevention. Our aim was to summarize the evidence from Cochrane and other systematic reviews evaluating the benefits or harms of vitamin D fortification of staple foods for household use. In April 2023, we systematically searched Ovid MEDLINE, Embase, Epistemonikos and the Cochrane Database of Systematic Reviews for systematic reviews investigating the effects of vitamin D fortification of food in general populations of any age. We used Cochrane methodology and assessed the methodological quality of included studies using AMSTAR (A MeaSurement Tool to Assess Systematic Reviews). We assessed the degree of overlap among reviews. All outcomes included in systematic reviews were assessed. The protocol is registered in PROSPERO (registration number: CRD42023420991). We included 27 systematic reviews out of 5028 records for analysis. Overall, 11 out of 12 systematic reviews calculating pooled estimates reported a significant increase in serum 25(OH)D concentrations. The mean change in serum 25(OH)D concentrations per additional 100 units of vitamin D ranged from 0.7 to 10.8 nmol/L. Fortification of food with vitamin D showed a reduction in the prevalence of vitamin D deficiency based on high-certainty evidence. Parathormone (PTH) levels were described to decrease, bone mineral density to increase, while the effects on other bone turnover markers were inconsistent. Fortification did not significantly impact most anthropometric parameters, but it seemed to positively influence lipid profiles. In summary, fortification of food with vitamin D results in a reduction of vitamin D deficiency and might increase serum 25(OH)D concentrations, to varying extents depending on the fortified vehicle and population characteristics. Additionally, fortification may have a positive impact on bone turnover and lipid metabolism but may only have a limited effect on anthropometric parameters.

Vitamin D Knowledge, Awareness, and Attitudes of Adolescents and Adults: A Systematic Review

INTRODUCTION

The aims of this systematic review were 2-fold: (1) evaluate the effect of vitamin D educational interventions on serum 25-hydroxyvitamin D (25-OHD) concentration in adolescents (aged 10-19 years) and adults, and (2) assess the association between serum 25-OHD concentration and vitamin D knowledge, awareness of vitamin D deficiency risk, and attitudes toward behaviors associated with acquiring vitamin D.

METHODS

Medline, CINAHL, Embase, and SPORTDiscus were systematically searched for studies reporting associations between serum 25-OHD concentration and vitamin D knowledge, awareness, and attitudes. Results were summarized narratively. Effect sizes were calculated when data were available.

RESULTS

Eight studies reported experimental effects (2 randomized controlled trials, 1 cluster randomized trial, 4 quasi-experiments, 1 clinical audit), and 14 reported cross-sectional associations. Seven of 8 interventions reported no effect of educational interventions on serum 25-OHD concentration. A slight majority (53%; κ = 19) of studies reported statistically significant associations between serum 25-OHD concentration and vitamin D knowledge and attitudes.

IMPLICATIONS FOR RESEARCH AND PRACTICE

The few educational interventions employed to increase serum 25-OHD concentration lack effectiveness. Future studies may use randomized controlled trial designs, enroll those at risk for vitamin D insufficiency and underrepresented in the literature, increase the salience of the information to the target population, and include safe sun exposure recommendations.

Effect of intratrial mean 25(OH)D concentration on diabetes risk, by race and weight: an ancillary analysis in the D2d study

BACKGROUND

Higher serum 25-hydroxyvitamin D [25(OH)D] is associated with lower type 2 diabetes risk. 25(OH)D varies due to skin pigmentation and weight.

OBJECTIVES

This analysis aims to determine whether the effect of vitamin D differs among people of color and those with overweight/obesity (who have higher diabetes risk) compared with individuals who are White or have normal weight.

METHODS

The D2d study is a randomized clinical trial in people with prediabetes that tested the effects of daily vitamin D3 4000 IU vs. placebo on diabetes risk (median followup 2.5 y). We compared baseline and intratrial mean 25(OH)D concentrations, defined as the mean of all available annual 25(OH)D values, among groups defined by self-reported race and body mass index (BMI). We used Cox proportional hazards models to assess the associations between intratrial mean 25(OH)D and diabetes risk by race- and BMI-based groups.

RESULTS

Asian (n=130), Black (n=616), and White (n=1616) participants were included. Both baseline and intratrial mean 25(OH)D concentrations differed significantly by race groups (both P < 0.001) and were lower in Asian and Black vs. White participants, and in those with higher vs. lower BMI adjusted for race (both P < 0.001). Compared with those with lower concentrations, Black and White participants with intratrial mean 25(OH)D ≥ 40 ng/mL had significantly reduced diabetes risk [HR (95% CI): Black: 0.51 (0.29, 0.92); White: 0.42 (0.30, 0.60)] and with a similar reduction in diabetes risk among Asian participants: 0.39 (0.14, 1.11). Compared with those with lower concentrations, participants with baseline BMI < 40 kg/m2 who achieved intratrial mean 25(OH)D concentrations ≥ 40 ng/mL had a significantly reduced diabetes risk. There was no statistically significant interaction between intratrial 25(OH)D and race or between intratrial 25(OH)D and BMI on diabetes risk.

CONCLUSIONS

Among people with prediabetes, particularly for Black and White race groups and those with BMI < 40 kg/m2, the optimal 25(OH)D concentration may be ≥ 40 ng/mL to optimize diabetes-prevention efforts. This trial was registered at clinicaltrials.gov as NCT01942694.

Implications of vitamin D deficiency in systemic inflammation and cardiovascular health

Clinical, epidemiological, and molecular studies have sufficiently highlighted the vitality of vitamin D [25(OH)D and 1,25(OH)2D] in human health and wellbeing. Globally, vitamin D deficiency (VDD) has become a public health concern among all age groups. There is a very high prevalence of VDD per the estimates from several epidemiological studies on different ethnic populations. But, population-specific scales do not support these estimates to define VDD clinically and consistent genetic associations. However, clinical studies have shown the relevance of serum vitamin D screening and oral supplementation in improving health conditions, pointing toward a more prominent role of vitamin D in health and wellness. Routinely, the serum concentration of vitamin D is measured to determine the deficiency and is correlated with physiological conditions and clinical symptoms. Recent research points toward a more inclusive role of vitamin D in different disease pathologies and is not just limited to otherwise bone health and overall growth. VDD contributes to the natural history of systemic ailments, including cardiovascular and systemic immune diseases. Considering its significant impact on premature morbidity and mortality, there is a compelling need to comprehensively review and document the direct and indirect implications of VDD in immune system deregulation, systemic inflammatory conditions, and cardio-metabolism. The recommendations from this review call for furthering our research concerning vitamin D and its direct and indirect implications.

Vitamin D status among infants and children in Shanghai, China: A hospital-based study

The variation in vitamin D status is still unclear. We aim to describe the vitamin D status among healthy infants and children in Shanghai (31° N latitude), one of the largest cities in China. We conducted a hospital-based, 2-year retrospective observational study and recruited children for health examination at the Tongren Hospital affiliated with Shanghai Jiao Tong University School of Medicine from January 2019 to December 2020. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using an enzyme-linked immunosorbent assay. A total of 6164 children aged 0-11 years were included. Of these, 94.4% of the serum 25(OH)D measurements at first assessment were within the range of 12-50 ng/mL. The median 25(OH)D level was 31.3 (IQR 25.6, 38.1) ng/mL, the percentages of 25(OH)D < 20 ng/mL and 25(OH)D < 30 ng/mL were 10.0% and 43.8%, respectively. Low vitamin D status (deficiency and insufficiency) differed significantly by age group (infants, toddlers, preschoolers, and schoolers) and seasonality (all p < .001), but not by gender. For the sub-group (n = 855) of children with repeated assessments, their low 25(OH)D levels increased significantly whether after about a 7-month (n = 351) or 12-month (n = 504) interval, and the increments of median 25(OH)D levels were 8.1 ng/mL and 2.1 ng/mL respectively (p < .001). This study documents the vitamin D status in Shanghai, showing that low vitamin D status is common in infants and children and suggesting that the assessment of 25(OH)D level is necessary for individuals who are at risk for deficiency or excess.

Efficacy of vitamin D3 supplementation on cancer mortality: Systematic review and individual patient data meta-analysis of randomised controlled trials

To evaluate the effect of vitamin D3 supplementation on cancer mortality in the general population and on prognosis in cancer patients, a systematic review and meta-analysis of randomised, placebo-controlled trials (RCTs) and individual patient data (IPD) was conducted. Overall, 14 RCTs with a total of 104,727 participants (2015 cancer deaths) were identified and 7 RCTs, including 90 % of all study participants (n = 94,068), could be included in the IPD meta-analyses. The main meta-analysis of the 14 RCTs yielded a statistically non-significant reduction in cancer mortality by 6 % (risk ratio (RR) [95%-confidence interval (95%CI)]: 0.94 [0.86-1.02]). Subgroup analyses revealed a 12 % lower cancer mortality in the vitamin D3 group compared with the placebo group in 10 trials with a daily dosing regimen (RR [95%CI]: 0.88 [0.78-0.98]), whereas no mortality reduction was seen in 4 trials using a bolus regimen (RR [95%CI]: 1.07 [0.91-1.24]; p-value for interaction: 0.042). The IPD meta-analysis (RR [95%CI]: 0.93 [0.84; 1.02]) confirmed the finding of all trials. The IPD were used to test effect modification by age, sex, body mass index, ethnicity, baseline serum 25-hydroxyvitamin D concentration, adherence and cancer-related factors but no statistically significant findings were obtained in meta-analyses of all trials. When restricted to trials with daily dosing in a post-hoc analysis, adults aged ≥ 70 years (RR [95%CI]: 0.83 [0.77; 0.98]) and subjects with vitamin D3 therapy initiation before cancer diagnosis (RR [95%CI]: 0.87 [0.69; 0.99]) appeared to benefit most from daily vitamin D3 supplementation. Measurements of baseline 25-hydroxyvitamin D levels and inclusion of other than non-Hispanic White adults were too sparse in the trials to draw conclusions. Results for all-cause and cancer-specific survival of participants with cancer were comparable to those obtained in the general population for cancer mortality. In conclusion, vitamin D3 did not reduce cancer mortality in the main meta-analysis of all RCTs because the observed risk reduction by 6 % was not statistically significant. However, a subgroup analysis revealed that vitamin D3 administered daily, in contrast to bolus supplementation, reduced cancer mortality by 12 %.

Vitamin D and Bone fragility in Individuals with Osteogenesis Imperfecta: A Scoping Review

Vitamin D affects several body functions, and thus general health, due to its pleiotropic activity. It plays a key role in bone metabolism, and its deficiency impacts bone development, leading to bone fragility. In osteogenesis imperfecta (OI), a group of hereditary connective tissue disorders characterized by bone fragility, additional factors, such as vitamin D deficiency, can affect the expression of the phenotype and aggravate the disorder. The aim of this scoping review was to assess the incidence of vitamin D deficit in OI patients and the association between vitamin D status and supplementation in individuals affected by OI. We searched the PubMed Central and Embase databases and included studies published between January/2000 and October/2022 evaluating vitamin D measurement and status (normal, insufficiency, deficiency) and supplementation for OI. A total of 263 articles were identified, of which 45 were screened by title and abstract, and 10 were included after a full-text review. The review showed that low levels of vitamin D was a frequent finding in OI patients. Vitamin D supplementation was mainly indicated along with drug therapy and calcium intake. Even if widely used in clinical practice, vitamin D supplementation for OI individuals still needs a better characterization and harmonized frame for its use in the clinical setting, as well as further studies focusing on its effect on bone fragility.

A Retrospective Chart Review Evaluating Changes in 25-Hydroxyvitamin D Levels among Patients Attending the University Healthcare Centre during the COVID-19 Pandemic

COVID-19-pandemic-related home confinement aids in limiting the spread of the virus but restricts exposure to sunlight, thereby possibly affecting 25(OH)D concentrations. This study aimed to investigate the effect of lockdown measures on 25(OH)D levels in outpatients visiting the healthcare centre over a period of two years. In this retrospective chart review, outpatients who visited a university healthcare centre for a health check-up over a period of two years were included. The patients' 25(OH)D serum levels and status were compared before, during, and after the lockdown periods. A total of 7234 patients were included in this study, with a mean age of 34.66 ± 16.78. The overall prevalence of 25(OH)D insufficiency, deficiency and sufficiency was 33.8%, 30.7% and 35.4%, respectively. The proportion of individuals with 25-(OH) D deficiency prior to lockdown was 29% and this proportion increased in the lockdown and post-lockdown periods to 31.1% and 32%, respectively. Although gender was less likely to have an impact on the 25 (OH) D level during the lockdown period (p = 0.630), we found an association between gender and 25 (OH) D status in the pre-lockdown and post-lockdown periods (p < 0.001 and p < 0.001, respectively). Another association between nationality and 25 (OH)D levels was found before, during and after the lockdown periods (p < 0.001). In addition, the youngest population, aged between 1 and 14, was strongly affected by the home confinement. Age had a positive and significant (p < 0.05) effect on 25 (OH) D status regardless of the different periods. Moreover, in the pre-lockdown period, male outpatients had 1.56 chance of having a sufficient level of 25 (OH)D. However, during the lockdown period, this chance decreased to 0.85 and then increased to 0.99 after the lockdown period. We found no statistically significant difference in the mean serum concentrations or in the prevalence of vitamin D insufficiency when we compared values from before, during and immediately after the COVID-19 lockdown period. However, there was a generally increased prevalence of vitamin D insufficiency in our study population. Another association between gender, nationality and age groups with 25(OH) D was found. Regular exposure to UVR is recommended for maintaining adequate vitamin D levels and to prevent vitamin D deficiency. Further research is needed to determine the best indications for vitamin D supplementation if confinement periods are extended and to consider the potential health consequences of prolonged confinement periods not only on vitamin D status but also on overall public health. The findings of this study may be considered by stakeholders for a targeted supplementation approach for risk groups.

Controlled randomized open label clinical study comparing the safety and efficacy of loading schedules in Vitamin D deficient patients

Rapidly restoring vitamin D levels to normal might be desirable in certain clinical situations. Larger doses of supplementation, have been shown to increase bone loss and the risk of falls. The optimal way to perform vitamin D loading safely and effectively is still not well elucidated. Our study was aimed to assess the safety and efficacy of two oral vitamin D loading protocols. Sixty-nine subjects with vitamin D deficiency (25OH-vitamin D (25(OH)D) < 20ng/ml) were included. Thirty-five participants received 30 000 IU of vitamin D₃ per week for 10 weeks (group Slower Loading Dose (SLD)) and thirty-four received 30 000 IU twice weekly for 5 weeks (group Moderate Loading Dose (MLD)) resulting in a loading dose of 300 000 IU for all subjects. Following this initial loading phase, both groups received 30 000 IU biweekly for 4 weeks to test whether the recommended daily vitamin D supplementation in range of 2,000 IU dose-equivalent could maintain the achieved levels. Seventy-nine percent of those subjects treated in group SLD and everyone in group MLD achieved a 25(OH)D level of 30ng/ml, which is the lower limit of the recommended normal range in Hungary. The mean increase in 25(OH)D was significantly higher in group MLD than in group SLD (38.6±1.80ng/ml vs 46,6±1.80ng/ml). No significant decrease was observed with the administration of the maintenance dose. There were no clinically significant changes in serum or urine calcium, and bone biomarkers in either group. Both protocols were found to be safe and effective, but the five-week dosing caused a significantly greater increase in 25(OH)D. A maintenance dose applied for four weeks after the loading protocol did not raise 25(OH)D levels further but maintained the achieved increase. The administration of 30 000 IU of vitamin D₃ twice weekly for five weeks is a rapid, effective and safe way to treat vitamin D deficiency in vitamin D deficient patients.

Contribution of Vitamin D Metabolites to Vitamin D Concentrations of Families Residing in Pune City

The objective was to explore the patterns of contribution from vitamin D metabolites (D2 and D3) to total vitamin D concentrations in Indian families. This cross-sectional study was carried out in slum-dwelling families residing in Pune city. Data on demography, socio-economic status, sunlight exposure, anthropometry, and biochemical parameters (serum 25OHD2, 25OHD3) via the liquid chromatography-tandem mass spectrometry method were collected. The results are presented for 437 participants (5 to 80 years). One-third were vitamin-D-deficient. Intake of foods containing vitamin D2 or D3 was rarely reported. Irrespective of gender, age, and vitamin D status, the contribution of D3 to total 25OHD concentrations far exceeded that of D2 (p < 0.05). The contribution of D2 ranged from 8% to 33% while that of D3 to 25OHD concentrations ranged from 67% to 92%. 25OHD3 is a major contributor to overall vitamin D concentrations, and the contribution of 25OHD2 was found to be negligible. This implies that sunlight and not diet is currently the major source of vitamin D. Considering that lifestyle and cultural practices may lead to insufficient sunlight exposure for large sections of the society, especially women, dietary contribution to vitamin D concentrations through fortification may play an important role in improving the vitamin D status of Indians.

Metabolomic analysis of the inhibitory effect of phthalates and bisphenol A on the antioxidant activity of vitamin D in human samples using liquid chromatography–mass spectrometry

Vitamin D is important because it has roles in maintaining musculoskeletal health, redox homeostasis, and the immune system; however, it is commonly dysregulated by endocrine disrupting chemicals, particularly phthalates and bisphenol A (BPA). Continuous exposure to phthalates and BPA may alter the endogenous metabolite profiles associated with vitamin D activity, although the specific metabolites are yet to be identified. In this study, we identified the endogenous metabolites altered by phthalates and BPA exposure through untargeted metabolic profiling and investigated the role of these metabolites in vitamin D activity. Plasma metabolic profiling using liquid chromatography-mass spectrometry was performed in two groups: severe 25-hydroxyvitamin D (25(OH)D) deficiency and high exposure to phthalates and BPA (Group A) and 25(OH)D deficiency and low exposure to phthalates and BPA (Group B). Multivariate analysis revealed a distinct separation between the two groups. A total of six metabolites were annotated, of which levels of two were significantly different between the two groups: platelet-activating factor (PAF) C16 or lysophosphatidylcholine (lysoPC) 18:0, and 11Z-eicosenamide. Plasma levels of PAF C16 or lysoPC 18:0 were increased in Group A and exhibited an area under the curve of 0.769 with an accuracy of 74.4% in a receiver operating characteristic curve analysis. These metabolites are generated as byproducts of lipid peroxidation, which supports the fact that phthalates and BPA induce oxidative stress in cells. Furthermore, PAF C16 and lysoPC 18:0 may be involved in the network that interferes with the antioxidant activity of vitamin D upon exposure to phthalates and BPA. This study results provide useful information on how the activity of vitamin D on the antioxidant system is inhibited when exposure to phthalates and BPA.

Serum 25-hydroxyvitamin D status of a large Chinese population from 30 provinces by LC-MS/MS measurement for consecutive 3 years: differences by age, sex, season and province

PURPOSE

We aimed to describe the vitamin D status and its distribution in different age groups, sexes, seasons, and provinces of a large Chinese population.

METHODS

This study retrospectively analyzed 1,528,685 results of serum 25-hydroxyvitamin D (25(OH)D) in the central laboratory of KingMed Diagnostics. The samples were from the individuals aged 0-119 years old in 30 provinces of China. Serum 25(OH)D was measured by an accurate commercial liquid chromatography-tandem mass spectrometry (LC-MS/MS) method from January 2017 to December 2019. The subjects were stratified by age, sex, the season of blood collection, and the province of residence.

RESULTS

The median 25(OH)D concentration was 25.5 ng/mL (interquartile range (IQR) 18.7-32.7 ng/mL) in males and 20.8 ng/mL (IQR 14.4-28.2 ng/mL) in females. Overall, the median 25(OH)D concentration decreased with age in both males and females. Males had a 0.2-2.4 ng/mL higher median 25(OH)D concentration than females in different age groups. Vitamin D deficiency (25(OH)D < 15 ng/mL for the individuals under 14 years old; < 20 ng/mL for the individuals over 14 years old) was found in 21.3% of males and 43.6% of females. Significant seasonal variation of serum 25(OH)D concentrations was repeatedly observed in 3 years, with median concentration higher in summer (25.3 ng/mL (IQR 19.3-31.9 ng/mL)) and lower in winter (18.5 ng/mL (IQR 12.3-26.6 ng/mL)). Vitamin D status varied by province. The median 25(OH)D concentration was the highest in Hainan (31.0 ng/mL (IQR 24.9-39.2 ng/mL)) and the lowest in Qinghai (14.4 ng/mL (IQR 9.6-20.0 ng/mL)). 25(OH)D₂ was detected in 12.2% of the results, and no significant seasonal variation was observed.

CONCLUSION

In China, vitamin D deficiency is prevalent in the population participating in clinical vitamin D measurement. Age and sex differences in vitamin D levels were observed in our study. Seasonal variation and provincial differences are important aspects of serum vitamin D status. 25(OH)D₂ cannot be ignored entirely in clinical measurement practice in China.

Effects of vitamin D supplementation on the regulation of blood lipid levels in prediabetic subjects: A meta-analysis

This meta-analysis aimed to systematically investigate whether vitamin D supplementation reduces blood lipid—total cholesterol (TC), LDL cholesterol (LDL-C), HDL cholesterol (HDL-C), and triglyceride (TG)—levels in prediabetic individuals. Pubmed, Web of Science, Cochrane Library, Embase, CNKI, and WANFANG databases were searched for studies published before 13 February 2022 (including 13 February 2022). Five articles were included. The results showed that vitamin D intervention led to a significant reduction in TG compared with control or placebo treatment (−0.42 [−0.59, −0.25], P &lt; 0.001). Subgroup analyses showed that this effect was particularly significant among the studies that included obese subjects (−0.46 [−0.65, −0.28], P &lt; 0.001), the studies that also included men (not only women) (−0.56 [−0.78, −0.34], P &lt; 0.001), and the studies with intervention durations longer than 1 year (−0.46 [−0.65, −0.28], P &lt; 0.001). Both relatively low doses of 2,857 IU/day (−0.65 [−0.92, −0.38], P &lt; 0.001) and relatively high doses of 8,571 IU/day (−0.28 [−0.54, −0.02] P = 0.04) of vitamin D supplementation reduced TG levels, and the effect was observed both in Northern Europe (−0.65 [−0.92, −0.38], P &lt; 0.001) and Asian (−0.25 [−0.48, −0.03], P = 0.03) country subgroups. No significant effects on TC, HDL-C, and LDL-C were shown. In conclusion, vitamin D supplementation might beneficially affect TG levels in individuals with prediabetes. Particularly longer durations of treatment, more than 1 year, with doses that correct vitamin deficiency/insufficiency, can have a beneficial effect. This meta-analysis was registered at www.crd.york.ac.uk/prospero (CRD42020160780).

Association of Vitamin D Deficiency and Insufficiency with Pathology in Hospitalized Patients

Vitamin D deficiency is one of the most common medical conditions, with approximately one billion people having low vitamin D levels. Vitamin D is associated with a pleiotropic effect (immunomodulatory, anti-inflammatory and antiviral), which can be essential for a better immune response. The aim of this research was to evaluate the prevalence of vitamin D deficiency/insufficiency in hospitalized patients focusing on demographic parameters as well as assessing the possibility of its associations with different comorbidities. Of 11,182 Romanian patients evaluated in the study over 2 years, 28.83% had vitamin D deficiency, 32.11% insufficiency and 39.05% had optimal vitamin D levels. The vitamin D deficiency was associated with cardiovascular disorders, malignancies, dysmetabolic disorders and SARS-CoV2 infection, older age and the male sex. Vitamin D deficiency was prevalent and showed pathology association, while insufficiency of vitamin D (20-30 ng/mL) had lower statistical relevance and represents a grey zone in vitamin D status. Guidelines and recommendations are necessary for homogeneity of the monitoring and management of inadequately vitamin D status in the risk categories.

COVID-19 infection and metabolic comorbidities: Mitigating role of nutritional sufficiency and drug - nutraceutical combinations of vitamin D

The vulnerability of human health is amplified in recent times with global increase in non-communicable diseases (due to lifestyle changes and environmental insults) and infectious diseases (caused by newer pathogens and drug-resistance strains). Clinical management of diseases is further complicated by disease severity caused by other comorbid factors. Drug-based therapy may not be the sole approach, particularly in scenarios like the COVID-19 pandemic, where there is no specific drug against SARS-CoV-2. Nutritional interventions are significant in armouring human populations in disease prevention, and as adjunctive therapy for disease alleviation. Amidst ongoing clinical trials to determine the efficacy of Vit. D against infections and associated complications, this review examines the pleiotropic benefits of nutritional adequacy of vitamin D (Vit. D) in combating viral infections (COVID-19), its severity and complications due to co-morbidities (obesity, diabetes, stroke and Kawasaki disease), based on research findings and clinical studies. Supplements of Vit. D in combination with other nutrients, and drugs, are suggested as promising preventive-health and adjunct-treatment strategies in the clinical management of viral infections with metabolic comorbidities.

Effect of vitamin D deficiency on metabolic syndrome among Korean shift workers

OBJECTIVE

This study aimed to investigate the effect of vitamin D deficiency on metabolic syndrome among shift workers.

METHODS

This study included 207 756 workers who underwent a comprehensive health examination at a large South Korean university hospital between 2012 and 2018. We performed multivariate-adjusted logistic regression analysis and analyzed mediation and exposure-mediator interaction.

RESULTS

Overall, 5.5% of the participants had metabolic syndrome. Compared to day work, the odds ratios (OR) of metabolic syndrome and vitamin D deficiency (<12 ng/mL) for shift work were 1.14 [95% confidence interval (CI) 1.06-1.22] and 1.63 (95% CI 1.57-1.70), respectively. Among shift workers, the OR of metabolic syndrome for vitamin D levels of 12-20 and <12 ng/mL, compared with a level of ≥20 ng/mL, were 1.36 (95% CI 1.15-1.61) and 1.51 (95% CI 1.26-1.81), respectively. Shift work and vitamin D deficiency showed an additive interaction; the relative excess risks due to interaction, attributable proportion, and synergy index were 0.26 (95% CI 0.08-0.44), 0.17 (95% CI 0.07-0.28), and 2.09 (95% CI 1.23-3.55), respectively. When vitamin D deficiency was treated as a mediator, the direct and total effects of shift work on metabolic syndrome were 1.12 (95% CI 1.04-1.22) and 1.15 (95% CI 1.07-1.25), respectively. The indirect effect was 1.03 (95% CI 1.02-1.04) and accounted for 18% of the total effect.

CONCLUSION

Vitamin D is a potential mediator of the impact of shift work on metabolic risk factors.

Examination of correlations between vitamin D and melatonin levels with sleep among women aged 18-49 years

OBJECTIVES

Although clinical research is still going on to determine any relationship between vitamin D and sleep regulation, only few studies have identified the role of vitamin D metabolism in sleep disorders. The current study aims to examine the incidence of vitamin D deficiency/insufficiency in the sample group and its effects on sleep quality and melatonin level.

METHODS

A cross-sectional study was designed. A total of 79 women aged 18-49 years who applied to the research and training hospital between 1 October and 30 November 2021 participated in the study. Data were collected using a socio-demographic questionnaire prepared by the authors and the Pittsburgh Sleep Quality Index (PSQI). Blood samples were taken from the participants, also, 25-OH-vitamin D3 and melatonin levels in serum samples were measured by ELISA.

RESULTS

The participants (n = 79) were aged 29.61 ± 11.14 years. The mean total PSQI scores of the participants were calculated as 5.77 ± 2.70. We determined that 64.6% of the participants had vitamin D deficiency, 21.5% had vitamin D insufficiency, and 13.9% of the participants were vitamin D sufficient. The mean melatonin level was found to be 24.77 ± 27.77 ng/L. We determined that an increase in the melatonin levels decreases the risk of vitamin D deficiency. Besides, our findings showed a good positive correlation between serum melatonin and 25 OH vitamin D3 levels (r = 0.544, p < 0.001).

CONCLUSION

Our results indicate that the correction of vitamin D insufficiency can positively affect melatonin levels, therefore, it may positively contribute to the treatment of sleep disorders related to melatonin deficiency.

Vitamin D Supplementation and Clinical Outcomes in Severe COVID-19 Patients-Randomized Controlled Trial

COVID-19 symptoms vary from asymptomatic cases to moderate and severe illness with patients needing hospitalization and intensive care treatment. Vitamin D is associated with severity of viral infections and has an immune-modulatory effect in immune response. Observational studies showed a negative association of low vitamin D levels and COVID-19 severity and mortality outcomes. In this study, we aimed to determine whether daily supplementation of vitamin D during intensive care unit (ICU) stay in COVID-19 patients with severe illness affects clinically relevant outcomes. Patients with COVID-19 disease in need of respiratory support admitted to the ICU were eligible for inclusion. Patients with low vitamin D levels were randomized into one of two groups: the intervention group received daily supplementation of vitamin D and the control group did not receive vitamin D supplementation. In total, 155 patients were randomized: 78 into the intervention group and 77 into the control group. There was no statistically significant difference in number of days spent on respiratory support, although the trial was underpowered for the main outcome. There was no difference in any of the secondary outcomes analyzed between two groups. Our study suggests no benefit in vitamin D supplementation to patients with severe COVID-19 disease admitted to the ICU and in need of respiratory support in any of the analyzed outcomes.

Bioavailability of vitamin D biofortified pork meat: results of an acute human crossover study in healthy adults

Vitamin D intakes are concerningly low. Food-based strategies are urgently warranted to increase vitamin D intakes and subsequently improve 25-hydroxyvitamin D (25(OH)D) concentrations. This acute randomised three-way crossover study investigated the efficacy of vitamin D biofortified pork derived from pigs exposed to UVB light to increase serum 25(OH)D₃ concentrations, compared to a dose-matched vitamin D₃ supplement and control pork in adults (n = 14). Blood samples were obtained at baseline and then 1.5, 3, 6, 9 and 24 h postprandially. There was a significant effect of time (p < 0.01) and a significant treatment*time interaction (p < 0.05). UV pork and supplement significantly increased within-group serum 25(OH)D₃ concentrations over timepoints (p < 0.05) (max. change 0.9 nmol/L (2.2%) UV pork, 1.5 nmol/L (3.5%) supplement, 0.7 nmol/L (1.9%) control). Vitamin D biofortified pork modestly increased 25(OH)D₃ concentrations and produced a similar response pattern as a dose-matched vitamin D supplement, but biofortification protocols should be further optimised to ensure differentiation from standard pork.

Impact of vitamin D on the prognosis after spinal cord injury: A systematic review

Vitamin D (VitD) insufficiency is a worldwide health problem and affects billions of people. Spinal cord injury (SCI) patients seem more susceptible to developing suboptimal levels of VitD. However, the literature regarding its impact on the prognosis of SCI is limited. Thus, in this review, we systematically investigated the published studies via a combination of keywords associated with SCI and VitD in four medical databases (Medline, Embase, Scopus, and Web of Science). All included studies were analyzed, and selected clinical data on the prevalence of VitD insufficiency (serum 25-hydroxyvitamin D < 30 ng/ml) and deficiency (serum 25-hydroxyvitamin D < 20 ng/ml) were collected for further meta-analysis via random effects. Through literature review, a total of 35 studies were eligible and included. The meta-analysis of VitD status (13 studies, 1,962 patients) indicated high prevalence of insufficiency (81.6% [75.7, 87.5]) and deficiency (52.5% [38.1, 66.9]) after SCI. Besides, low levels of VitD were reported to be associated with a higher risk of skeletal diseases, venous thromboembolism, psychoneurological syndromes, and chest illness after injury. Existing literature suggested that supplemental therapy might act as an adjuvant treatment to facilitate post-injury rehabilitation. Non-human experimental studies highlighted the neuroprotective effect of VitD, which was associated with enhancing axonal and neuronal survival, suppressing neuroinflammation, and modulating autophagy. Therefore, the current evidence suggests that the prevalence of VitD insufficiency is high in the SCI population, and low-level VitD may impair functional restoration after SCI. VitD supplemental treatment may have potential benefits to accelerate rehabilitation in mechanistically related processes after SCI. However, due to the limitation of the available evidence, more well-designed randomized controlled trials and mechanism experimental research are still needed to validate its therapeutic effect, elucidate its neuroprotective mechanism, and develop novel treatments.

Determination of a Serum 25-Hydroxyvitamin D Reference Ranges in Japanese Adults Using Fully Automated Liquid Chromatography-Tandem Mass Spectrometry

BACKGROUND

Despite an increasing interest in vitamin D status, a reference range of the nutrient has not been fully established. This is partly due to a paucity of standardized measuring systems with high throughput. In addition, the range may vary by populations and may change with modernization of lifestyles.

OBJECTIVES

This study aims to calculate the current reference concentration of 25-hydroxyvitamin D (25(OH)D) among healthy people living in an urban area in Japan.

METHODS

A newly developed fully automated liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) system was used to measure serum 25(OH)D concentrations. Reproducibility was assessed by measuring standardized samples. Accuracy was validated by comparing with commercially available immunoassays. Then, mass screening was conducted targeting participants who received medical checkups in Tokyo from April 2019 to March 2020, and the reference ranges were calculated.

RESULTS

The coefficients of variations of interoperator and interday reproducibility were 4.1%-8.5% and 3.7%-8.0% for 25-hydroxyvitamin D₂ (25(OH)D2) and 4.7%-7.0% and 4.0%-6.9% for 25-hydroxyvitamine D3, respectively. The measured total 25(OH)D concentrations correlated well with those measured by immunoassays. In total, 5518 participants were measured for 25(OH)D concentrations, among whom 98% showed inadequate concentrations (<30 ng/mL). The reference ranges of total 25(OH)D for female, male, and total participants were 7-30 ng/mL, 5-27 ng/mL, and 6-29 ng/mL, respectively. After excluding those with abnormal renal and liver function, the range was 6-30 ng/mL.

CONCLUSIONS

The high prevalence of vitamin D insufficiency among seemingly healthy population may be attributed to lifestyle characteristics of people living in urban areas of Japan, including spending less time outdoors and lower intake of traditional foods. Longitudinal follow-up and mass screenings targeting different population will help elucidate reasons for discrepancies between official guidelines and the observed concentrations, to which the well-validated measurement system is essential.

Serum Vitamin D Level and Gut Microbiota in Women

Obesity and vitamin D deficiency are two major public health concerns. Evidence suggests that alteration in gut microbiota composition is a possible risk factor for obesity. Additionally, altered vitamin D status has a potential role in shaping the gut microbial community. Further, the prevalence of obesity has been rising in the Middle East, especially among women of reproductive age, which is of specific concern due to its adverse effects on the health of their offspring. To date, limited evidence is available on the association between gut microbiota composition and vitamin D levels in Arab women. This study aims to identify the associations between serum vitamin D, gut microbiota, and obesity among Saudi females. The current study is a case-control study including 92 women aged 18 to 25 years, (n = 48) with normal weight and (n = 44) with obesity. Anthropometric, biochemical, lifestyle data, and fecal samples were collected and analyzed. We used shotgun metagenomic sequencing to characterize microbial communities of stool samples. Vitamin D levels were significantly associated with alpha and beta diversities. Serum vitamin D levels were positively associated with bacteria known to regulate immunological responses; Bacteroides thetaiotaomicron in the normal weight group (r = 0.34, p = 0.03) and Bifidobacterium adolescentis in the obesity group (r = 0.33, p = 0.04). In conclusion, the findings suggest that vitamin D status may play a role in regulating the gut microbiota composition by inhibiting the growth of pathogenic bacteria while nourishing the beneficial strains.

Vitamin D, a Secosteroid Hormone and Its Multifunctional Receptor, Vitamin D Receptor, in Alzheimer's Type Neurodegeneration

Vitamin D is a secosteroid hormone exerting neurosteroid-like properties. Its well-known nuclear hormone receptor, and recently proposed as a mitochondrial transcription factor, vitamin D receptor, acts for its primary functions. The second receptor is an endoplasmic reticulum protein, protein disulfide isomerase A3 (PDIA3), suggested to act as a rapid response. Vitamin D has effects on various systems, particularly through calcium metabolism. Among them, the nervous system has an important place in the context of our subject. Recent studies have shown that vitamin D and its receptors have numerous effects on the nervous system. Neurodegeneration is a long-term process. Throughout a human life span, so is vitamin D deficiency. Our previous studies and others have suggested that the out-come of long-term vitamin D deficiency (hypovitaminosis D or inefficient utilization of vitamin D), may lead neurons to be vulnerable to aging and neurodegeneration. We suggest that keeping vitamin D levels at adequate levels at all stages of life, considering new approaches such as agonists that can activate vitamin D receptors, and utilizing other derivatives produced in the synthesis process with UVB are crucial when considering vitamin D-based intervention studies. Given most aspects of vitamin D, this review outlines how vitamin D and its receptors work and are involved in neurodegeneration, emphasizing Alzheimer's disease.

Vitamin D in Neurological Diseases

Vitamin D may have multiple effects on the nervous system and its deficiency can represent a possible risk factor for the development of many neurological diseases. Recent studies are also trying to clarify the different effects of vitamin D supplementation over the course of progressive neurological diseases. In this narrative review, we summarise vitamin D chemistry, metabolism, mechanisms of action, and the recommended daily intake. The role of vitamin D on gene transcription and the immune response is also reviewed. Finally, we discuss the scientific evidence that links low 25-hydroxyvitamin D concentrations to the onset and progression of severe neurological diseases, such as multiple sclerosis, Parkinson's disease, Alzheimer's disease, migraine, diabetic neuropathy and amyotrophic lateral sclerosis. Completed and ongoing clinical trials on vitamin D supplementation in neurological diseases are listed.

Machine Learning-Based Prediction of Elevated PTH Levels Among the US General Population

CONTEXT

Although elevated parathyroid hormone (PTH) levels are associated with higher mortality risks, the evidence is limited as to when PTH is expected to be elevated and thus should be measured among the general population.

OBJECTIVE

This work aimed to build a machine learning-based prediction model of elevated PTH levels based on demographic, lifestyle, and biochemical data among US adults.

METHODS

This population-based study included adults aged 20 years or older with a measurement of serum intact PTH from the National Health and Nutrition Examination Survey (NHANES) 2003 to 2006. We used the NHANES 2003 to 2004 cohort (n = 4096) to train 6 machine-learning prediction models (logistic regression with and without splines, lasso regression, random forest, gradient-boosting machines [GBMs], and SuperLearner). Then, we used the NHANES 2005 to 2006 cohort (n = 4112) to evaluate the model performance including area under the receiver operating characteristic curve (AUC).

RESULTS

Of 8208 US adults, 753 (9.2%) showed PTH greater than 74 pg/mL. Across 6 algorithms, the highest AUC was observed among random forest (AUC [95% CI] = 0.79 [0.76-0.81]), GBM (AUC [95% CI] = 0.78 [0.75-0.81]), and SuperLearner (AUC [95% CI] = 0.79 [0.76-0.81]). The AUC improved from 0.69 to 0.77 when we added cubic splines for the estimated glomerular filtration rate (eGFR) in the logistic regression models. Logistic regression models with splines showed the best calibration performance (calibration slope [95% CI] = 0.96 [0.86-1.06]), while other algorithms were less calibrated. Among all covariates included, eGFR was the most important predictor of the random forest model and GBM.

CONCLUSION

In this nationally representative data in the United States, we developed a prediction model that potentially helps us to make accurate and early detection of elevated PTH in general clinical practice. Future studies are warranted to assess whether this prediction tool for elevated PTH would improve adverse health outcomes.

Vitamin D Status for Chinese Children and Adolescents in CNNHS 2016-2017

Vitamin D is very important in maintaining children's bone health because of its regulatory role in calcium and phosphate metabolism. To better understand vitamin D status and related risk factors of children and adolescents in China, this study analyzed the 25-hydroxyvitamin-D (25(OH)D) concentration of children and adolescents aged 6-17 years in China and assessed the risk factors of vitamin D deficiency and insufficiency. We analyzed the data of 25(OH)D concentration collected from the China National Nutrition and Health Survey of Children and Lactating Mothers in 2016-2017 (CNNHS 2016-2017). The age, sex, region type, ethnicities, season, weight and height were recorded, measured by unified questionnaire, equipment and standards. The concentration of 25(OH)D was detected by LC-MS/MS. A total of 64,391 participants from the cross-sectional study of CNNHS in 2016-2017 were included in this study. The median serum 25(OH)D concentration was 17.70 (13.20-22.68) ng/mL, 18.70 (14.10-23.80) ng/mL in boys and 16.60 (12.40-21.40) ng/mL in girls. The total prevalence rate of vitamin D deficiency and insufficiency was 65.98% when the cut-off was 20 ng/mL, 60.42% for boys and 71.99% for girls. According to the results of logistic regression analysis, girls aged above 12 y, living in midlands and northern regions, in spring and winter seasons and with abdominal obesity will have a significantly increased risk of vitamin D deficiency and insufficiency among Chinese children and adolescents. The results showed that vitamin D deficiency and insufficiency are very common among children and adolescents aged 6-17 y in China. They should be encouraged to have more effective sunlight exposure, increased intake of vitamin D from food or supplements in their diet, especially for those aged above 12 y, living in the northern or midlands areas, in spring and winter, and abdominally obese.

Vitamin D: A Factor affecting the Success of Type 1 Tympanoplasty

OBJECTIVES

Vitamin D (VD) plays role in wound healing and protection against infections. The relationship between plasma VD level and the outcomes of Type 1 tympanoplasty (T1T) has not been studied before.

METHODS

A total of 101 patients with chronic otitis media scheduled for T1T were divided into four groups in relation with their VD levels as severe insufficiency, insufficiency, mild-to-modest deficiency and optimal VD level groups. Graft success, hearing improvement and postoperative infection rates were compared among the groups in 12-month follow-up period.

RESULTS

The graft success rate (P = 0.014) and air-bone gap gain (P = 0.004) were significantly higher, and postoperative infection rate was significantly lower (P < 0.001) in optimal VD level group.

CONCLUSION

25-OH VD deficiency should be considered as a factor for failure in T1T. VD replacement may increase success of tympanoplasty in patients with low preoperative serum VD levels.