VitD Supplementation Research Articles

Implications of vitamin D levels or status for mortality in rheumatoid arthritis: analysis of 2001-2018 data from the National Health and Nutrition Examination Survey.

Inadequate levels of vitamin D (VitD) have been linked to increased rates of various health conditions and mortality. However, little is known about the relationship between mortality outcomes and 25-hydroxyvitamin D [25(OH)D] levels in individuals with rheumatoid arthritis (RA). This study aimed to examine this association using data from the National Health and Nutrition Examination Survey. A cohort of 2,290 individuals aged 20 to 85 years with RA was analyzed. Lower 25(OH)D levels were inversely associated with all-cause mortality, with a hazard ratio (HR) of 0.91 (0.87 to 0.96) per 10 nmol/L increase. Comparatively, the HR for the VitD insufficiency group was 0.64 (0.50 to 0.83), and for the VitD sufficiency group, it was 0.60 (0.44 to 0.80), both compared to the VitD deficiency group. Cause-specific analysis showed that higher 25(OH)D levels were associated with reduced mortality from heart disease (HR: 0.88, 0.82 to 0.95) and malignant neoplasms (HR: 0.86, 0.79 to 0.94). No significant correlation was found between 25(OH)D levels and cause-specific mortalities for other conditions. Stratified by gender, the HR for males was 0.92 (0.85 to 0.99) and for females was 0.91 (0.86 to 0.98) per 10 nmol/L increase in 25(OH)D levels. Among individuals aged 20-59 years, no significant correlation was observed, while for those aged 60 years and older, the HR was 0.86 (0.82 to 0.90) per 10 nmol/L increase. Nonlinear analysis identified a sharp increase in HR below 59.95 nmol/L, while HR remained below 1 for 25(OH)D levels above 59.95 nmol/L. This study reveals a strong negative correlation between 25(OH)D levels and overall mortality in individuals with RA. Notably, this association is particularly significant for mortality related to heart disease and malignant neoplasms. Targeted VitD supplementation should be emphasized, especially in individuals aged 60 years and older with RA. The proposed minimum threshold for adequate 25(OH)D levels in the RA population is 60 nmol/L.

6652 Precision Diagnostic Approaches for Assessing Clinical Vitamin D Status

Abstract Disclosure: Z. Shahidzadeh Yazdi: None. E.A. Streeten: None. H.B. Whitlatch: Grant Recipient; Self; Regeneron Pharmaceuticals. M.E. Montasser: Grant Recipient; Self; Regeneron Pharmaceuticals. A.L. Beitelshees: None. S.I. Taylor: Consulting Fee; Self; Ionis Pharmaceuticals Inc.. Background . The body has evolved effective homeostatic mechanisms to maintain free 1,25-dihydroxyvitamin D [1,25(OH)2D] within narrow physiological ranges. Using a mathematical model to quantitate 24-hydroxylase activity, we concluded that mild-moderate vitamin D [VitD] deficiency suppresses 24-hydroxylase activity (the first line of defense), thereby suppressing clearance of 1,25(OH)2D. Severe VitD deficiency triggers secondary hyperparathyroidism (the second line of defense) to sustain physiological levels of 1,25(OH)2D. Objective. To compare performance of various indices of VitD status in predicting whether homeostatic mechanisms have been triggered. Methods. We studied 11 otherwise healthy VitD deficient (25-hydroxyvitamin D [25(OH)D] ≤20 ng/mL) participants before and after VitD3 supplementation (50,000 IU once or twice a week depending on BMI for 4-6 weeks). We measured 25(OH)D, 1,25(OH)2D, 24,25-dihydroxyvitamin D [24,25(OH)2D], PTH, and FGF23 before and after VitD3 supplementation. We calculated three VitD metabolite ratios and also a PTH index (i.e., PTH level before divided by PTH level after VitD3 supplementation) to normalize PTH levels relative to each individual’s setpoint. We then compared the correlation between the PTH index and various indices of VitD status. Results. VitD3 supplements induced a 2.7-fold increase (p=0.0006) in mean 25(OH)D and a 4.3-fold increase (p=0.0002) in 24,25(OH)2D, but did not change 1,25(OH)2D, PTH, or FGF23. While relative 24-hydroxylase activity (h) was highly correlated with the 1,25(OH)2D/24,25(OH)2D ratio (ρ2=0.94; p=3E-13), it was less well correlated with the 24,25(OH)2D/25(OH) ratio (ρ2=0.67; p=3E-06) and baseline total 25(OH)D (ρ2=0.72; p=7E-07). Furthermore, we investigated the correlation between the PTH index and baseline 25(OH)D and three VitD metabolite ratios. The correlation coefficient was higher when we plotted the PTH index as a function of baseline 25(OH)D before VitD3 supplementation (R2=0.23; p=2E-06) compared to the correlation of baseline PTH with baseline 25(OH)D (R2=0.08; p=5E-05). While the correlation coefficient for the correlation of PTH index with 1,25(OH)2D/24,25(OH)2D was 0.60 (R2=0.36; p=0.0002), it was 0.44 for 25(OH)D/1,25(OH)2D ratio (R2=0.20; p=0.0001) and 0.35 for the 24,25(OH)2D/25(OH)D ratio (R2=0.12; p=2E-06). Conclusions. Measuring total 25(OH)D level did not provide optimal assessment of clinical VitD status – probably because it does not account for the threefold inter-individual variation in VitD binding protein level. Of all the indices, the 1,25(OH)2D/24,25(OH)2D ratio best predicted triggering of two homeostatic mechanisms: suppression of 24-hydroxylase and induction of secondary hyperparathyroidism due to VitD deficiency. Presentation: 6/2/2024

Vitamin D Supplementation Does Not Enhance Gains in Muscle Strength and Lean Body Mass or Influence Cardiorespiratory Fitness in Vitamin D-Insufficient Middle-Aged Men Engaged in Resistance Training.

This study checked whether vitamin D (Vit-D) supplementation improves the efficacy of resistance training (RT) in terms of increasing muscle strength and lean body mass (LBM), and influencing cardiorespiratory fitness (VO2max) in Vit-D-deficient middle-aged healthy men. Participants (n = 28) were quasi-randomly assigned to one of two groups, which, in a double-blind manner, supplemented their diet daily with either Vit-D (8000 IU; VD) or placebo (PLC) during participation in a 12-week supervised RT program. During the intervention, serum Vit-D concentrations increased 2.6-fold (p < 0.001) in the VD group, while no changes occurred in the PLC group. Muscle strength gains (p < 0.001) as measured in seven exercises performed on RT equipment and increases (p < 0.001) in LBM were similar in the two groups. Total fat mass, percent total fat, and percent android fat decreased (p < 0.05) to a similar extent in both groups, but there was no change in VO2max in either group. In conclusion, in healthy Vit-D-insufficient middle-aged men engaged in resistance training, Vit-D supplementation increases serum 25(OH)D levels but does not enhance gains in muscle strength and LBM, or decreases in fat mass and fat percentage, and does not affect cardiorespiratory fitness.

SARS-CoV-2 induced vitamin D deficiency and psychological stress: a manifestation of autoimmune disease onset.

The global SARS-CoV-2 pandemic significantly altered lifestyles, access to healthcare, and social interactions, introducing unprecedented physical and psychological stress all over the world. This study explores the relationship between psychological stress, vitamin D (Vit-D) levels, and autoimmune connective tissue diseases, including systemic lupus erythematosus, systemic sclerosis, polymyositis, dermatomyositis, and rheumatoid arthritis. The analysis was based on over one million patient data points derived from anti-nuclear antibody (ANA) testing conducted both before and during the COVID-19 pandemic 2017-2021. In a subset of patients, longitudinal data were collected bi-yearly to yearly over 5-8 years using the same three-month criteria. The dataset was analyzed using GraphPad Prism9 using paired t-tests or ordinary one-way ANOVA with a significance threshold of p < 0.05 to ensure robust correlations between the variables. Data indicated that Vit-D levels peaked between 2017 and 2019 before declining, while ANA data demonstrated a rise in autoimmune connective tissue disease cases during the pandemic, reaching a peak in 2021. A clear correlation was observed, with autoimmune disease incidence increasing as Vit-D levels decreased. In-depth case analysis revealed that declining Vit-D levels preceded higher ANA titers and increased autoimmune disease severity, whereas improvements in Vit-D levels were associated with reduced ANA titers and less severe disease manifestations. The findings suggest that maintaining mental health and ensuring adequate Vit-D supplementation could be essential strategies for mitigating autoimmune disease risks and maintaining immune stability, particularly in pandemic scenarios. Clinically, these results underscore the need for early interventions targeting both psychological well-being and Vit-D levels to reduce the burden of autoimmune diseases.

Supplementation with 25-hydroxicolecalciferol increases the nutritional efficiency and carcass growth of grazing Nellore young bulls

We aimed to evaluate the effect of 25-OH Vit D3 (Hy-D, DSM, Brazil) supplementation on the performance, body measures, and carcass characteristics of growing and finishing grazing Nellore young bulls. Two experiments were conducted. In Experiment 1, 150 animals (body weight (BW) of 350 ± 23kg) were separated into 6 treatment groups: protein supplement (PS); protein supplement with monensin (PS+Mon); protein supplement with 25-OH Vit D3 (PS+Vit D3); protein supplement with monensin and 25-OH Vit D3 (PS+Mon+Vit D3); protein-energetic supplement (PE); protein-energetic supplement with 25-OH Vit D3 (PE+Vit D3). In Experiment 2, 240 animals with an initial BW of 390 ± 16kg were separated into the same protein-energetic supplement treatment groups used in Experiment 1 with or without 25-OH Vit D3 (two treatments). Animals in the different treatments of Experiment 1 had similar ADG and final BW values (P > 0.05), except for those that received monensin in PS, which showed lower ADG (P < 0.05). The addition of monensin to the PS inhibited increases in the body measures (P < 0.05) except for the height at withers (P > 0.05). Animals that received PE+Vit D3 showed greater increases in rib width (P < 0.05). In Experiment 2, animals that received 25-OH Vit D3 were 8.0kg heavier than the animals that did not receive this supplement (P < 0.05). The results show that supplementation with 25-OH Vit D3 is a promising and effective method of improving carcass weight and yield in finishing beef cattle during grazing.

Vitamin D deficiency and fragility fractures in Bangladeshi elderly patients and efficacy of Vit-D supplementation

Vitamin D deficiency and fragility fractures in Bangladeshi elderly patients and efficacy of Vit-D supplementation

The effect of active vitamin D supplementation on body weight and composition: A meta-analysis of individual participant data

Background & aimsObesity is associated with vitamin D (VitD) deficiency. However, previous studies showed mixed effects of VitD (25-hydroxyVitD/calcidiol) supplementation on body weight. The biological actions of VitD require the hydroxylation of inactive VitD into active VitD (1.25-dihydroxyVitD/calcitriol). This step is highly regulated; therefore, supplementing with inactive VitD might not be sufficient to overcome the potential adverse health effects of VitD deficiency. The objective of this study was to conduct a systematic review and individual participant data (IPD) meta-analysis of data acquired from randomised placebo-controlled calcitriol trials (RCTs) to determine the effects of calcitriol on body weight and weight-related parameters. MethodsStudies were identified from MEDLINE, EMBASE, and CENTRAL databases up to January 27, 2024, and excluded those involving dialysis or cancer patients. We obtained IPD from eligible trials and assessed bias using the Cochrane Collaboration risk-of-bias tool and methodological quality using the Heyland Methodological Quality Score. The study was prospectively registered with PROSPERO (CRD42017076202). ResultsAlthough none of the studies reported information regarding our primary objective, we obtained IPD for 411 patients, with 206 randomised to receive calcitriol and 205 to placebo. This dataset enabled us to conduct an IPD meta-analysis with 17,084 person-months of follow-up (median: 11 months). Meta-analysis showed that calcitriol does not alter body weight, BMI, waist circumference, fat mass or lean body mass compared to placebo. Adjusting for age and sex did not alter the outcomes. ConclusionsIn conclusion, this systematic review and IPD meta-analysis indicate that calcitriol does not affect body weight in normal-weight postmenopausal women and lean patients with type 1 diabetes nor in people suffering from obesity, type 2 diabetes and chronic kidney disease. Whether calcitriol lowers body weight in VitD-sufficient people with obesity remains to be elucidated.

Can Vitamin D Supplementation Improve Inflammation in Relapsing-Remitting Multiple Sclerosis Patients?

(1) Background: Studies indicate that vitamin D (VitD) may reduce inflammation in multiple sclerosis (MS). The aim of the study was to assess the effect of supplementation with different doses of VitD on inflammation in relapsing-remitting MS (RRMS) patients. (2) Methods: The effect of 6-month supplementation with different doses of oral VitD (2000 IU/day) in a high-dose group (HD, n = 23) and a low-dose group (15,960 IU/month) (LD, n = 29) on selected markers of inflammation was assessed in 52 RRMS patients. (3) Results: Females constituted the majority of participants (63.46%). The median age [years] was 39.5 [34.5-49.8] and 47 [40.0-55.0] in the HD and LD groups, respectively. Significant differences were observed in age (p = 0.028), body weight (p = 0.014) and height (p = 0.001) between the study groups. Considering the BMI, statistically significant differences were not found (p = 0.496). The median 25(OH)D concentration [ng/mL] increased from 23.023 [15.578-25.76] in the HD group and 28.318 [20.644-32.232] in the LD group to 29.819 [24.937-38.064] and 30.837 [25.382-36.789], respectively (p < 0.01), and the increase was significantly higher in the HD group (p = 0.01). Hypovitaminosis D was found in most patients (71.2%) initially, and serum VitD levels were still <30.0 ng/mL in 46.2% of the participants at the follow-up. A significant increase in the levels of IL-4, IL-6, IL-17A, IL-22, IL-23 and TNF -α [pg/mL] and a decrease in IL-10 levels were reported during the study (p < 0.01). A significant positive correlation was observed between 25(OH)D serum levels and sCD40L (R = 0.33; p < 0.05) and TNF-α (R = 0.28; p < 0.05), and a significant negative correlation was reported between 25(OH)D and IL-23 (R = -0.32; p < 0.01) at the beginning of the study. (4) Conclusions: In RRMS patients, the doses of VitD were probably too low to induce beneficial effects on inflammation. Further studies are warranted to determine the effect of VitD supplementation on inflammatory markers in MS patients.

Sulfated vitamin D metabolites represent prominent roles in serum and in breastmilk of lactating women

BackgroundConcentrations of vitamin D (VitD) and 25-hydroxyvitamin D (25OHD) in breastmilk are low despite the essential role of VitD for normal infant bone development, yet additional metabolic forms of vitamin D may be present. This study evaluates the contribution of sulfated vitamin D metabolites, vitamin D3-sulfate (VitD3-S) and 25-hydroxyvitamin D3-sulfate (25OHD3-S) for lactating women and assesses the response to high-dose VitD3 supplementation. MethodsSerum and breastmilk were measured before and after 28 days with 5000 IU/day VitD3 intake in 20 lactating women. Concentrations of VitD3-S and 25OHD3-S in milk, and 25OHD2, 25OHD3, 25OHD3-S, VitD3 and VitD3-S in serum were determined by mass spectrometry. ResultsBaseline vitamin D status was categorized as sufficient (mean ± SD serum 25OHD3 69 ± 19 nmol/L), and both serum VitD3 and 25OHD3 increased following supplementation (p < 0.001). 25OHD3-S was 91 ± 19 nmol/L in serum and 0.47 ± 0.09 nmol/L in breastmilk. VitD3-S concentrations were 2.92 ± 0.70 nmol/L in serum and 6.4 ± 3.9 nmol/L in breastmilk. Neither sulfated metabolite significantly changed with supplementation in either serum or breastmilk. ConclusionsSulfated vitamin D metabolites have prominent roles for women during lactation with 25OHD3-S highly abundant in serum and VitD3-S distinctly abundant in breastmilk. These data support the notion that 25OHD3-S and VitD3-S may have physiological relevance during lactation and nutritional usage for nursing infants.

Vitamin D affects the risk of disease activity in multiple sclerosis

BackgroundVitamin D (VitD) affects the risk of multiple sclerosis (MS), but the impact on disease activity is controversial. We assessed whether VitD is associated with the No-Evidence of Disease Activity-3...

Can Vitamin D Reduce Inflammation? The Influence of Supplementation on Selected Immunological Markers.

There is increasing evidence that vitamin D (VitD) supplementation may reduce inflammation in individuals with multiple sclerosis (MS). The aim of this study was to evaluate the effect of different doses of VitD on selected markers of inflammation in patients with relapsing-remitting MS (RRMS). Participants were divided depending on the supplemented dose of VitD into a high-dose (2000 IU/d; HD) group and a low-dose (15,960 IU/month; LD) group (n = 23 and n = 29, respectively). The concentration of 25(OH)D and the levels of CXCL16, PTX3, ALCAM, IL-1RA, and OPG were measured initially and after six months of VitD supplementation in blood serum. A significant increase in the concentrations of CXCL16, PTX3, and OPG was observed during the study (p = 0.02, p = 0.01, and p < 0.01, respectively). Furthermore, a higher increase in PTX3 and OPG in the LD group was observed (p = 0.04 and p = 0.03, respectively). A significant positive correlation was observed between the 25(OH)D serum concentration and PTX3 (R = 0.28, p < 0.05) and OPG (R = 0.28, p < 0.05) only at the beginning of the study. In patients with RRMS, such doses of VitD might be too low to induce obvious beneficial effects on the pro-inflammatory and inflammatory balance.

Asthmatic patients with vitamin D deficiency: Can vitamin D supplementation make a difference.

Asthma is a major public health concern due to its persistent inflammation of the airways. The intricate and widely variable epidemiology of asthma among nations and populations is a result of the interplay between genetic, environmental, and socioeconomic factors. This study aims to investigate whether VitD supplementation can reduce the frequency of exacerbations (including the frequency of exacerbations requiring systemic corticosteroids and the frequency of exacerbations necessitating trips to the hospital or emergency room, or both) and improve pulmonary function (clinical indicators such as the FEV1% predicted value). Computers were used to search Pubmed, Medline, ISI Web of Science, Embase, Cachrane Library, CNKI, CBM, VIP, and the Wanfang Database. Asthma/asthma, VitD/VitD, lung function/lung function, retrieval time is from database setup to October 8, 2021, to search all randomized controlled trials (RCTs) on the effect of VitD on human asthma and to retroactively incorporate references to literature were all included in the search criteria. After rigorous screening, quality evaluation, and data extraction of the included literature by two reviewers independently, heterogeneity tests and sensitivity analyses were performed. The findings show that a total of 12 relevant studies meeting the inclusion criteria were finally included, including 649 cases in the experimental group and 646 cases in the control group. VitD intervention reduced the number of asthma exacerbations, including the rate of exacerbations requiring systemic corticosteroid therapy and the rate of acute exacerbations requiring emergency department or hospital visits or both. In the outcome of lung function (FEV1% predicted value), it was shown that VitD supplementation improved lung function; in the outcome of serum 25-hydroxyVitD levels, it was shown that VitD supplementation increased serum 25-hydroxyVitD levels.

Recovery of optimal vitamin D improves responsiveness to phosphodiesterase-5 inhibitors therapy in pulmonary arterial hypertension

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – EU funding. Main funding source(s): R.A. has received funding from the European Union’s Horizon 2020 research and innovation programme under Marie-Curie grant agreement Nº 847635. Introduction Vitamin D (vitD) deficiency is highly prevalent in patients with pulmonary arterial hypertension (PAH). Moreover, PAH-patients with lower levels of vitD have worse prognosis. We demonstrated that in animals with PAH and severe deficit of vitD, restoring vitD levels to an optimal range partially improves some pathophysiological features of PAH. Also, recent evidence suggests that vitD deficiency may cause insufficient response to phosphodiesterase-5 inhibitors (PDE5i), such as sildenafil, in some patients with PAH. Thus, in this study, we hypothesize that the recovery of optimal vitD levels in experimental PAH might help to improve responsiveness to PDE5i therapy. Methods Male Wistar rats were fed a vitD-free diet for five weeks and then received a single dose of Su5416 (20 mg/Kg) and were exposed to vitD-free diet and chronic hypoxia (10% O2) for three weeks to induce PAH. Following this, vitD deficient rats with PAH were housed in room air and divided into two groups: (a) daily tadalafil therapy (oral;10mg/kg) + continued vitD-free diet (n=9) or (b) daily tadalafil therapy (oral;10mg/kg) + single oral dose of 50,000 IU/Kg of vitD plus standard diet (n=9) for four weeks. Animals were then used for exercise capacity evaluation, invasive haemodynamic, pulmonary vascular analysis, and sample collection. Evolution of cardiac (dys)function was assessed by echocardiography. Results Recovering optimal vitD levels improved pulmonary endothelial function, measured by an increase in the endothelium-dependent vasodilator response to acetylcholine. It also increased the vasodilator response to sildenafil. Moreover, pulmonary small artery (&amp;lt;55 µm) remodeling was decreased in vitD-restored group, as measured by a decline in mean lumen/total ratio and mean medial thickness. In a morphometric analysis, vitD treatment attenuated increases in both right ventricle (RV) and right atrial hypertrophy, as well as the fulton index. VitD supplementation also improved the exercise capacity with increases seen in distance run, evaluated by endurance tests in a treadmill set. RV catheterization showed that vitD did not decreased the RV dysfunction, evaluated by end-systolic and end-diastolic pressure. Similar to the RV, no alterations were observed in pulmonary artery pressures. However, echocardiographic analysis revealed an improved pulmonary flow in the vitD-restored group, where pulmonary artery acceleration time normalized to ejection time ratio and pulmonary artery velocity-time integral were increased. It also improved tricuspid annular plane systolic excursion (TAPSE). Conclusion Altogether, these data suggest that in animals with PAH treated with tadalafil, restoring vitD levels to an optimal range improves some pathophysiological features of PAH. Therefore, in addition to recovery of optimal vitD status being indicated to restore calcium homeostasis in those PAH patients with severe deficiency, it might help to improve responsiveness to PDE5i.

#495 Effect of Vit D supplementation on bone mineral density in haemodialysis patients. A comparative study

Abstract Background and Aims Low serum 25(OH) vit D levels are usually observed in haemodialysis patients. In this population, vit D deficiency is associated with secondary hyperparathyroidism (SHPT) and low bone mineral density (BMD). Although, vit D supplements are routinely prescribed in haemodialysis patients, their exact role in preventing bone loss hasn't been studied thoroughly. The primary aim of this study was to estimate the effect of cholecalciferol (vit D3) use on BMD changes of haemodialysis patients. Secondary aim was to evaluate how parathyroid hormone (PTH), phosphorus and calcium levels are affected by vit D3 supplementation. Method Twelve (12) haemodialysis patients with low levels of serum vit D were included. All of them had their bone density measured with Dual - Energy X-Ray Absorptionmetry (DXA). The study population was then divided in two groups. Half of them (6 patients) received oral cholecarciferol (study group) and the rest continued with their standard treatment (control group). Initial dose of cholecalciferol was 25000 iu weekly and titrated upwards until 25 (OH) vit D levels were reaching 20 ng/ml. Then, cholecarciferol was continued in maintenance dose to keep vit D levels between 20 and 40 ng/ml. Thirty (30) months later, DXA was repeated in all patients. BMD in total hip region was evaluated. During the study period, phosphorus, calcium and PTH levels were measured monthly while 25 (OH) vit D levels were measured every three months. Results Patients’ mean age was 61.9 (±8.8) years. There were no differences in age, initial BMD, PTH or vit D levels between the two groups. Overall, initial mean vit D value was 8.5 ng/ml. At the end of the study, vit D levels had increased to 23.6 ng/ml in the study group while remaining unchanged in the control group. At the beginning of the study, mean BMD in the whole population was 0.742 gr/cm3 and it decreased by 0.042 gr/cm3 after 30 months. No differences in BMD change were observed between the two groups (ΔBMD was −0.057 versus -0.029 gr/cm3 in the study and control group respectively, p = 0.12). PTH levels were reduced in the study group and increased in the control group but the observed difference was not significant (p = 0.11). Phosphorus and calcium levels were not affected by vit D supplementation. Of note, three fractures were observed in the study group and one in the control group during the study period. Conclusion Vit D3 supplementation didn't seem to affect the rate of bone loss in haemodialysis patients, at least in the doses received and levels of 25 (OH) achieved above. Its exact effect in PTH levels as well as in the rate of bone fractures needs to be verified by larger studies.

The Role of 24-hydroxylase in Homeostatic Regulation of 1,25-dihydroxyvitamin D

Background. Because of the importance of vitamin D (VitD) in calcium balance and bone health, the body has evolved effective homeostatic mechanisms to maintain 1,25-dihydroxyvitamin D [1,25(OH)2D] — the biologically active form — in a narrow physiological range. Objective and hypothesis. We developed a mathematical model to investigate homeostatic mechanisms regulating VitD metabolism with the objective of elucidating regulatory mechanisms maintaining levels of 1,25(OH)2D within a narrow physiological range despite wide variation in availability of VitD. Methods. We studied 11 otherwise healthy VitD deficient [25(OH)D&lt;20 ng/mL] participants before and after VitD3 supplementation (50,000 IU once or twice a week depending on BMI for 4-6 weeks). We measured 25(OH)D, 1,25(OH)2D, 24,25(OH)2D, PTH, and FGF23. We used a 2-tailed paired Student’s t-test to analyze our data; p=0.05 was selected as the criterion for statistical significance. This represents a secondary analysis of a previously published clinical trial [Shahidzadeh Yazdi et al. (2023) J Clin Endocrinol Metab, doi: 10.1210/clinem/dgad554]. Results. VitD3 supplements induced a significant 2.7-fold increase (p=0.0006) in mean 25(OH)D and a 4.3-fold increase (p=0.0002) in 24,25(OH)2D, but did not change 1,25(OH)2D, PTH, or FGF23. Our model showed that 24-hydroxylase activity was regulated over a 10-fold range — with maximal induction for 25(OH)D&gt;50 ng/mL and maximal suppression for 25(OH)D&lt;10-20 ng/mL). Because 24-hydroxylase catalyzes metabolic clearance of 1,25(OH)2D, high levels protect against VitD toxicity and low levels preserve 1,25(OH)2D when VitD is scarce. Thus, suppression of 24-hydroxylase activity is a homeostatic mechanism reflecting the body’s perception of VitD deficiency. Accordingly, measurements of 24,25(OH)2D levels can contribute to assessment of VitD status. However, measurements of total levels of all VitD metabolites [including 24,25(OH)2D] are confounded by the ~3-fold inter-individual variation in VitD binding protein (VDBP) levels. Fortunately, the ratio of 1,25(OH)2D /24,25(OH)2D is independent of VDBP levels. Our analysis suggests that this ratio provides a superior assessment of VitD status compared to the current recommendation to measure total 25(OH)D. For example, 24-hydroxylase activity is highly correlated with 1,25(OH)2D /24,25(OH)2D (ρ2=0.91) but less well correlated with 25(OH)D (ρ2=0.91). Conclusions. The body has two defense mechanisms to protect against VitD deficiency. The first line of defense is suppression of 24-hydroxylase, which is triggered by mild-moderate VitD deficiency and preserves VitD from degradation. However, at times of severe VitD deficiency, the first line of defense may be insuffcient to maintain 1,25(OH)2D in a physiological range. Therefore, the body triggers a second line of defense — secondary hyperparathyroidism, which in turn upregulates 1-hydroxylation and increases production of 1,25(OH)2D. By better understanding the physiology of homeostatic regulation of VitD metabolism, physicians can advance the state-of-the-art in diagnosing and treating VitD deficiency. Funding: R01DK118942; T32DK098107. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Vitamin D loaded into lipid nanoparticles shows insulinotropic effect in INS-1E cells

Increasing evidence suggests a beneficial role of vitamin D (VitD) supplementation in addressing the widespread VitD deficiency, but currently used VitD3 formulations present low bioavailability and toxicity constrains. Hence, poly(L-lactide-co-glycolide) (PLGA) nanoparticles (NPs), solid-lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were investigated to circumvent these issues. PLGA NPs prepared by emulsification or nanoprecipitation presented 74 or 200 nm, and association efficiency (AE) of 68 % and 17 %, respectively, and a rapid burst release of VitD3. Both SLN and NLCs presented higher polydispersity and larger NPs size, around 500 nm, which could be reduced to around 200 nm by use of hot high-pressure homogenization in the case of NLCs. VitD3 was efficiently loaded in both SLNs and NLCs with an AE of 82 and 99 %, respectively. While SLNs showed burst release, NLCs allowed a sustained release of VitD3 for nearly one month. Furthermore, NLCs showed high stability with maintenance of VitD3 loading for up to one month at 4 °C and no cytotoxic effects on INS-1E cells up to 72 h. A trending increase (around 30 %) on glucose-dependent insulin secretion was observed by INS-1E cells pre-treated with VitD3. This effect was consistently observed in the free form and after loading on NLCs. Overall, this work contributed to further elucidation on a suitable delivery system for VitD3 and on the effects of this metabolite on β cell function.

An Adapted Questionnaire Tailored for Assessing the Risk of Vitamin D Deficiency in Children That Is Proving Useful in Guiding Clinical Interventions.

The identification of vitamin D (VitD) deficiency in pediatric populations is essential for preventive healthcare. We refined and tested the Evaluation of Deficiency Questionnaire (EVIDENCe-Q) for its utility in detecting VitD insufficiency among children. We enrolled 201 pediatric patients (aged between 3 and 18 years). Clinical evaluation and serum vitamin D levels were assessed in all subjects. The EVIDENCe-Q was updated to incorporate factors influencing VitD biosynthesis, intake, assimilation, and metabolism, with scores spanning from 0 (optimal) to 36 (poor). We established scores for severe deficiency (<10 mg/dL) at 20, deficiency (<20 mg/dL) at 22, and insufficiency (<30 mg/dL) at 28. A score of 20 or greater was determined as the optimal cut-off for distinguishing VitD deficient from sufficient statuses, as evidenced by ROC curve analysis AUC = 0.7066; SE = 0.0841; sensitivity 100%, 95% CI 0.561-1. The most accurate alignment was seen with VitD insufficiency, defined as 25-OH-D3 < 20 ng/mL. This study confirms that the EVIDENCe-Q is a valid instrument for assessing the risk of vitamin D deficiency and insufficiency in children. It offers a practical approach for determining the need for clinical intervention and dietary supplementation of VitD in the pediatric population.

Potential Interaction between WNT16 and Vitamin D on Bone Qualities in Adolescent Idiopathic Scoliosis Patients and Healthy Controls.

Adolescent idiopathic scoliosis (AIS) is a three-dimensional spinal deformity that is associated with low bone mineral density (BMD). Vitamin D (Vit-D) supplementation has been suggested to improve BMD in AIS, and its outcomes may be related to genetic factors. The present study aimed to (a) investigate the synergistic effect between a low BMD-related gene (wingless-related integration site 16, WNT16) and two important Vit-D pathway genes (Vit-D receptor, VDR, and Vit-D binding protein, VDBP) on serum Vit-D and bone qualities in Chinese AIS patients and healthy adolescents, and (b) to further investigate the effect of ablating Wnt16 on the cortical bone quality and whether diets with different dosages of Vit-D would further influence bone quality during the rapid growth phase in mice in the absence of Wnt16. A total of 519 girls (318 AIS vs. 201 controls) were recruited, and three selected single-nucleotide polymorphisms (SNPs) (WNT16 rs3801387, VDBP rs2282679, and VDR rs2228570) were genotyped. The serum 25(OH)Vit-D level was significantly associated with VDBP rs2282679 alleles (OR = -4.844; 95% CI, -7.521 to -2.167, p < 0.001). Significant multi-locus models were identified by generalized multifactor dimensionality reduction (GMDR) analyses on the serum 25(OH)Vit-D level (p = 0.006) and trabecular area (p = 0.044). In the gene-edited animal study, Wnt16 global knockout (KO) and wildtype (WT) male mice were provided with different Vit-D diets (control chow (1000 IU/Kg) vs. Vit-D-deficient chow (Nil in Vit-D) vs. high-dose Vit-D chow (20,000 IU/Kg)) from 4 weeks to 10 weeks old. Wnt16 global KO mice had significantly lower serum 25(OH)Vit-D levels and higher liver Vdbp mRNA expression levels than WT mice. In addition, Wnt16 global KO mice showed a decrease in bone density, cortical thickness and cortical area compared with WT mice. Interestingly, high-dose Vit-D chow led to lower bone density, cortical thickness, and cortical area in WT mice, which were less obvious in Wnt16 global KO mice. In conclusion, WNT16 may regulate the serum 25(OH)Vit-D level and bone qualities, which might be associated with VDBP expression. Further investigations with a larger sample size and wider spectrum of scoliosis severity are required to validate our findings regarding the interaction between WNT16 and Vit-D status in patients with AIS.

Highly selective whole-cell 25-hydroxyvitamin D3 synthesis using molybdenum-dependent C25-steroid dehydrogenase and cyclodextrin recycling

BackgroundThe global prevalence of vitamin D (VitD) deficiency associated with numerous acute and chronic diseases has led to strategies to improve the VitD status through dietary intake of VitD-fortified foods and VitD supplementation. In this context, the circulating form of VitD3 (cholecalciferol) in the human body, 25-hydroxy-VitD3 (calcifediol, 25OHVitD3), has a much higher efficacy in improving the VitD status, which has motivated researchers to develop methods for its effective and sustainable synthesis. Conventional monooxygenase-/peroxygenase-based biocatalytic platforms for the conversion of VitD3 to value-added 25OHVitD3 are generally limited by a low selectivity and yield, costly reliance on cyclodextrins and electron donor systems, or by the use of toxic co-substrates.ResultsIn this study, we used a whole-cell approach for biocatalytic 25OHVitD3 synthesis, in which a molybdenum-dependent steroid C25 dehydrogenase was produced in the denitrifying bacterium Thauera aromatica under semi-aerobic conditions, where the activity of the enzyme remained stable. This enzyme uses water as a highly selective VitD3 hydroxylating agent and is independent of an electron donor system. High density suspensions of resting cells producing steroid C25 dehydrogenase catalysed the conversion of VitD3 to 25OHVitD3 using either O2 via the endogenous respiratory chain or externally added ferricyanide as low cost electron acceptor. The maximum 25OHVitD3 titer achieved was 1.85 g L–1 within 50 h with a yield of 99%, which is 2.2 times higher than the highest reported value obtained with previous biocatalytic systems. In addition, we developed a simple method for the recycling of the costly VitD3 solubiliser cyclodextrin, which could be reused for 10 reaction cycles without a significant loss of quality or quantity.ConclusionsThe established steroid C25 dehydrogenase-based whole-cell system for the value-adding conversion of VitD3 to 25OHVitD3 offers a number of advantages in comparison to conventional oxygenase-/peroxygenase-based systems including its high selectivity, independence from an electron donor system, and the higher product titer and yield. Together with the established cyclodextrin recycling procedure, the established system provides an attractive platform for large-scale 25OHVitD3 synthesis.

Vitamin D3 reverses immune tolerance and enhances the cytotoxicity of effector T cells in coal pneumoconiosis

Coal worker's pneumoconiosis (CWP) is a common occupational disease that coal miners are highly susceptible due to long-term exposure to coal dust particles (CDP). CWP can induce the accumulation of immune cells surrounding the bronchioles and alveoli in the lungs, resulting in pulmonary fibrosis and compromised immune function. Using single-cell RNA sequencing (scRNA-Seq), our previous studies disclose that CDP exposure triggers heterogeneity of transcriptional profiles in mouse pneumoconiosis, while Vitamin D3 (VitD3) supplementation reduces CDP-induced cytotoxicity; however, the mechanism by which how VitD3 regulates immune status in coal pneumoconiosis remains unclear. In this study, we elucidated the heterogeneity of pulmonary lymphocytes in mice exposed to CDP and demonstrated the therapeutic efficacy of VitD3 using scRNA-Seq dataset. The validation of key lymphocyte markers and their functional molecules was performed using immunofluorescence. The results demonstrated that VitD3 increased the number of naive T cells by modulating CD4 + T cell differentiation and decreased the number of Treg cells in CDP-exposed mice, thereby enhancing the cytotoxic activity of CD8 + effector T cells. These effects markedly alleviated lung fibrosis and symptoms. Taken together, the mechanism by which VitD3 regulates the functions of lymphocytes in CWP provides a new perspective for further research on the prevention and treatment of CWP.