Forecasting levels of serum 25-hydroxyvitamin D based on dietary intake, lifestyle and personal determinants in a sample of Southern Europeans.

Vitamin D is an essential nutrient to be consumed in the habitual dietary intake, whose deficiency is associated with various disturbances. This study represents a validation of vitamin D status estimation using a semi-quantitative FFQ, together with data from additional physical activity and lifestyle questionnaires. This information was combined to forecast the serum vitamin D status. Different statistical methods were applied to estimate the vitamin D status using predictors based on diet and lifestyle. Serum vitamin D was predicted using linear regression (with leave-one-out cross-validation) and random forest models. Intraclass correlation coefficients, Lin's agreement coefficients, Bland-Altman plots and other methods were used to assess the accuracy of the predicted v. observed serum values. Data were collected in Spain. A total of 220 healthy volunteers aged between 18 and 78 years were included in this study. They completed validated questionnaires and agreed to provide blood samples to measure serum 25-hydroxyvitamin D (25(OH)D) levels. The common final predictors in both models were age, sex, sunlight exposure, vitamin D dietary intake (as assessed by the FFQ), BMI, time spent walking, physical activity and skin reaction after sun exposure. The intraclass correlation coefficient for the prediction was 0·60 (95 % CI: 0·52, 0·67; P < 0·001) using the random forest model. The magnitude of the correlation was moderate, which means that our estimation could be useful in future epidemiological studies to establish a link between the predicted 25(OH)D values and the occurrence of several clinical outcomes in larger cohorts.

The effect of vitamin D supplementation on serum levels of fibroblast growth factor- 23: A systematic review and meta-analysis of randomized controlled trials.

Previous studies of the effect of vtamin D on serum levels of fibroblast growth factor- 23 (FGF-23) have yeilded an inconsistent findings. This systematic review and meta-analysis of randomized controlled trials (RCTs) sought to investigate the effect of vitamin D supplementation on serum levels of FGF-23. PubMed, Scopus, ISI Web of Science, and the Cochrane Library were searched, from database inception to November 2020, for RCTs that evaluated the effects of native or active vitamin D supplementation on serum levels of FGF-23 in adults. Weighted mean difference (WMD) were calculated and random effects meta-analysis was used to estimate the overall effects. Twenty-seven trials were included in the meta-analysis. Supplementation with native vitamin D (23 studies, n = 2247 participants; weighted mean difference [WMD] = 0.5 pg/mL, 95 % CI: -0.52 to 1.51, P = 0.33; I2 = 29.9 %), and active vitamin D (5 studies, n = 342 participants, WMD = 29.45 pg/mL, 95 % CI: -3.9 to 62.81, P = 0.08; I2 = 99.3%) had no significant effects on serum FGF-23 concentration. In subgroup analyses, supplementation with ergocalciferol (3 studies, n = 205 participants; WMD = 18.27 pg/mL, 95 % CI: 5.36-31.17, P = 0.006), and daily dosing regimens (9 studies, n = 1374 participants; WMD = 0.41 pg/mL, 95 % CI: 0.22 to 0.59, P < 0.001) increased serum FGF-23 levels compared to control. Overall, our findings revealed no significan effect of vitamin D supplementation on serum FGF-23 concentration. However, further high quality, large-scale studies are needed to better elucidate this relationship.

Relative Efficacy of Vitamin D2 and Vitamin D3 in Improving Vitamin D Status: Systematic Review and Meta-Analysis.

BACKGROUND: Widespread prevalence of vitamin D deficiency has been documented globally. Commonly used interventions to address this deficiency include supplementation and/or fortification with either ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3), but the relative efficacy of these two vitamers is unclear. The current study aimed to evaluate the relative efficacy of ergocalciferol (vitamin D2) and cholecalciferol (vitamin D3) for raising the serum levels of vitamin D metabolites and functional indicators including serum parathyroid (PTH) levels, isometric muscle strength, hand grip strength and bone mineral density. METHODS: Randomized and non-randomized controlled studies evaluating relative efficacy of ergocalciferol and cholecalciferol were systematically reviewed to synthesize quantitative and qualitative evidence as per the recommendations of according to "Preferred Reporting Items for Systematic reviews and Meta-analysis" guidelines. Search terms were constructed on the basis of the "participants", "intervention", "control", "outcome" and "study type" (PICOS) strategy to systematically search the popular electronic databases. Relevant data from studies meeting inclusion and exclusion criteria were extracted and analyzed. Meta-regression, subgroup and sensitivity analyses were performed to investigate the influence of study-level characteristics including intervention dosage, frequency of dosing, interval between the last dose and test for outcome assessment, participant characteristics and analytical methods. RESULTS: Apparently healthy human participants (n = 1277) from 24 studies were included for meta-analysis. The quantitative analysis suggested higher efficacy of cholecalciferol than ergocalciferol in improving total 25(OH)D (mean difference: 15.69, 95%CI: 9.46 to 21.93 nmol/L) and reducing PTH levels, consistently across variable participant demographics, dosage and vehicle of supplementation. Meta-regression suggested smaller differences in the efficacy of cholecalciferol and ergocalciferol at lower doses. Average daily dose was the single significant predictor of effect size, as revealed by multivariate meta-regression analysis. CONCLUSIONS: Compared to ergocalciferol, cholecalciferol intervention was more efficacious in improving vitamin D status (serum levels of total 25(OH)D and 25(OH)D3) and regulating PTH levels, irrespective of the participant demographics, dosage and vehicle of supplementation.

The impact of CASR A990G polymorphism in response to cinacalcet treatment in hemodialysis patients with secondary hyperparathyroidism.

The objective of this study was to determine the impact of calcium sensing receptor (CASR) A990G genetic polymorphism on parathyroid hormone (PTH) lowering response to cinacalcet treatment when controlling for significant influencing clinical factors. This retrospective study was conducted on 135 Thai hemodialysis (HD) patients with secondary hyperparathyroidism (SHPT). CASR A990G genotypes were determined. The patients were identified as either G carriers (heterozygous or homozygous CASR 990G allele carriers) or noncarriers (homozygous CASR 990A carriers). Tested covariates were baseline PTH level (bPTH), baseline serum phosphate (bPhos), baseline serum calcium (bCa), baseline calcitriol equivalent dose (bCtriol), baseline ergocalciferol dose (bErgo), and age. The ANCOVA showed that intact PTH levels after 12 weeks of cinacalcet treatment (PTHw12) was significantly lower among G carriers compared with noncarriers after controlling for bPTH, bPhos, bCtriol, and bErgo (F(1, 127) = 15.472, p < 0.001), with the adjusted mean difference of 253.7 pg/mL. The logistic regression analysis revealed that the odds of a G carrier achieving 30% PTH reduction after 12-week cinacalcet treatment were 3.968 times greater than the odds for a noncarrier after adjusting for bPhos, bCtriol, and age. In conclusion, the CASR A990G polymorphism significantly influences cinacalcet response in HD patients with SHPT.

Differences in the Concentration of Vitamin D Metabolites in Plasma Due to the Low-Carbohydrate-High-Fat Diet and the Eastern European Diet-A Pilot Study.

Vitamin D deficiency is a global problem with many health consequences, and it is currently recommended to supplement vitamin D. Change of diet should also be considered to ensure adequate vitamin D in the human body. The aim of this study was to assess the concentration of vitamin D metabolites in two different groups: one group on the low-carbohydrate-high-fat (LCHF) diet and the other group on the Eastern European (EE) diet. In the first stage, 817 participants declaring traditional EE diet or LCHF diet were investigated. Nutrition (self-reported 3-day estimated food record) and basic anthropometric parameters were assessed. After extra screening, 67 participants on the EE diet and 41 on the LCHF diet were qualified for the second stage. Plasma 25-hydroxycholecalciferol (25(OH)D3) and (25(OH)D2) concentration was measured by the validated HPLC-MS/MS method. Plasma 25(OH)D3 concentration was significantly higher in the group on the LCHF diet (34.9 ± 15.9 ng/mL) than in the group on the EE diet (22.6 ± 12.1 ng/mL). No statistical differences were observed in plasma 25(OH)D2 concentration between the study groups (p > 0.05). Women had a higher plasma 25(OH)D2 concentration than men regardless of diet type. The LCHF diet had a positive influence on plasma vitamin D concentration. However, long-term use of the LCHF diet remains contentious due to the high risk of cardiovascular disease. This study confirmed that the type of diet influences the concentration of vitamin D metabolites in the plasma.

Vitamin D Metabolites and Clinical Outcome in Hospitalized COVID-19 Patients.

(1) Background: Vitamin D, a well-established regulator of calcium and phosphate metabolism, also has immune-modulatory functions. An uncontrolled immune response and cytokine storm are tightly linked to fatal courses of COVID-19. The present retrospective study aimed to inves-tigate vitamin D status markers and vitamin D degradation products in a mixed cohort of 148 hospitalized COVID-19 patients with various clinical courses of COVID-19. (2) Methods: The serum concentrations of 25(OH)D3, 25(OH)D2, 24,25(OH)2D3, and 25,26(OH)2D3 were determined by a validated liquid-chromatography tandem mass-spectrometry method in leftover serum samples from 148 COVID-19 patients that were admitted to the University Hospital of the Medical Uni-versity of Graz between April and November 2020. Anthropometric and clinical data, as well as outcomes were obtained from the laboratory and hospital information systems. (3) Results: From the 148 patients, 34 (23%) died within 30 days after admission. The frequency of fatal outcomes did not differ between males and females. Non-survivors were significantly older than survivors, had higher peak concentrations of IL-6 and CRP, and required mechanical ventilation more frequently. The serum concentrations of all vitamin D metabolites and the vitamin D metabolite ratio (VMR) did not differ significantly between survivors and non-survivors. Additionally, the need for res-piratory support was unrelated to the serum concentrations of 25(OH)D vitamin D and the two vitamin D catabolites, as well as the VMR. (4) Conclusion: The present results do not support a relevant role of vitamin D for the course and outcome of COVID-19.

Increased 1,25(OH)2-Vitamin D Concentrations after Energy Restriction Are Associated with Changes in Skeletal Muscle Phenotype.

The influence of energy restriction (ER) on muscle is controversial, and the mechanisms are not well understood. To study the effect of ER on skeletal muscle phenotype and the influence of vitamin D, rats (n = 34) were fed a control diet or an ER diet. Muscle mass, muscle somatic index (MSI), fiber-type composition, fiber size, and metabolic activity were studied in tibialis cranialis (TC) and soleus (SOL) muscles. Plasma vitamin D metabolites and renal expression of enzymes involved in vitamin D metabolism were measured. In the ER group, muscle weight was unchanged in TC and decreased by 12% in SOL, but MSI increased in both muscles (p < 0.0001) by 55% and 36%, respectively. Histomorphometric studies showed 14% increase in the percentage of type IIA fibers and 13% reduction in type IIX fibers in TC of ER rats. Decreased size of type I fibers and reduced oxidative activity was identified in SOL of ER rats. An increase in plasma 1,25(OH)2-vitamin D (169.7 ± 6.8 vs. 85.4 ± 11.5 pg/mL, p < 0.0001) with kidney up-regulation of CYP27b1 and down-regulation of CYP24a1 was observed in ER rats. Plasma vitamin D correlated with MSI in both muscles (p < 0.001), with the percentages of type IIA and type IIX fibers in TC and with the oxidative profile in SOL. In conclusion, ER preserves skeletal muscle mass, improves contractile phenotype in phasic muscles (TC), and reduces energy expenditure in antigravity muscles (SOL). These beneficial effects are closely related to the increases in vitamin D secondary to ER.

Assessing the impact of a mushroom-derived food ingredient on vitamin D levels in healthy volunteers.

BACKGROUND: Prevalence of vitamin D insufficiency/deficiency has been noted in athletic populations, although less is known about recreationally active individuals. Biofortification of natural food sources (e.g. UV radiated mushrooms) may support vitamin D status and is therefore of current scientific and commercial interest. The aim of this study was to assess the impact of a mushroom-derived food ingredient on vitamin D status in recreationally active, healthy volunteers. METHODS: Twenty-eight participants were randomly assigned to either: 25 µg (1000 IU) encapsulated natural mushroom-derived vitamin D2; matched-dose encapsulated vitamin D3 or placebo (PL) for 12 weeks. Venous blood samples were collected at baseline, week 6 and 12 for analysis of serum 25(OH)D2 and 25(OH)D3 using liquid chromatography mass spectrometry. Habitual dietary intake and activity were monitored across the intervention. RESULTS: Vitamin D status (25(OH)DTOTAL) was significantly increased with vitamin D3 supplementation from 46.1 ± 5.3 nmol·L- 1 to 88.0 ± 8.6 nmol·L- 1 (p < 0.0001) across the intervention, coupled with an expected rise in 25(OH)D3 concentrations from 38.8 ± 5.2 nmol·L- 1 to 82.0 ± 7.9 nmol·L- 1 (p < 0.0001). In contrast, D2 supplementation increased 25(OH)D2 by + 347% (7.0 ± 1.1 nmol·L- 1 to 31.4 ± 2.1 nmol·L- 1, p < 0.0001), but resulted in a - 42% reduction in 25(OH)D3 by week 6 (p = 0.001). A net + 14% increase in 25(OH)DTOTAL was established with D2 supplementation by week 12 (p > 0.05), which was not statistically different to D3. Vitamin D status was maintained with PL, following an initial - 15% reduction by week 6 (p ≤ 0.046 compared to both supplement groups). CONCLUSIONS: The use of a UV radiated mushroom food ingredient was effective in maintaining 25(OH)DTOTAL in healthy, recreationally active volunteers. This may offer an adjunct strategy in supporting vitamin D intake. However, consistent with the literature, the use of vitamin D3 supplementation likely offers benefits when acute elevation in vitamin D status is warranted.

Vitamin D3 deficiency is associated with more severe insulin resistance and metformin use in patients with type 2 diabetes.

BACKGROUND: Vitamin D3 (vit. D3) deficiency is considered as one of the main factors involved in the development of type 2 diabetes (T2D). We assessed insulin resistance (IR), ß-cell functional activity and metabolic profile according to 25(OH) vit. D3 status in patients with T2D. METHODS: The study included 109 patients with T2D, divided in 3 groups: group 1 (N.=11) with normal levels of vit. D3 (>30 ng/mL); group 2 (N.=38) with vit. D3 insufficiency (21-29 ng/mL); and group 3 (N.=60) with vit. D3 deficiency (<20 ng/mL). IR and ß-cell functional activity were assessed as change in C-peptide concentration and homeostasis model assessment-estimated (HOMA) ß-cell function which was calculated using HOMA2 calculator. RESULTS: Patients with vit. D3 deficiency presented significantly higher C-peptide concentration compared to other groups. HOMA2 (3.29±1.89 vs. 2.12±0.71; P=0.049) and hemoglobin (H8b)A1c (9.11±1.63 vs. 7.75±1.06; P=0.016) levels changed significantly only in patients with vit. D3 deficiency compared to diabetics with normal vit. D3 levels. Furthermore, in univariate Pearson's correlation analysis, we observed significant association between vit. D3 levels and C-peptide, insulin sensitivity, HOMA2, triglyceride-glucose index, HbA1c and Body Mass Index, only in the vit. D3 deficiency group. In multivariate logistic regression analysis, poor glycemic control, as defined by HbA1c levels, was independent from metformin use while high density lipoprotein-cholesterol levels were associated with vit. D3 deficiency. CONCLUSIONS: Our study demonstrated that vit. D3 deficiency in patients with T2D was associated with more severe IR, poor glycemic control and obesity compared to normal status or vit. D3 insufficiency.

Association of vitamin D2 and D3 with type 2 diabetes complications.

AIMS: Vitamin D measurement is a composite of vitamin D2 (25(OH)D2) and D3 (25(OH)D3) levels, and its deficiency is associated with the development of type 2 diabetes (T2DM) and diabetic complications; vitamin D deficiency may be treated with vitamin D2 supplements. This study was undertaken to determine if vitamin D2 and D3 levels differed between those with and without T2DM in this Middle Eastern population, and the relationship between diabetic microvascular complications and vitamin D2 and vitamin D3 levels in subjects with T2DM. METHODS: Four hundred ninety-six Qatari subjects, 274 with and 222 without T2DM participated in the study. Plasma levels of total vitamin D2 and D3 were measured by LC-MS/MS analysis. RESULTS: All subjects were taking vitamin D2 and none were taking D3 supplements. Vitamin D2 levels were higher in diabetics, particularly in females, and higher levels were associated with hypertension and dyslipidemia in the diabetic subjects (p < 0.001), but were not related to diabetic retinopathy or nephropathy. Vitamin D3 levels measured in the same subjects were lower in diabetics, particularly in females (p < 0.001), were unrelated to dyslipidemia or hypertension, but were associated with retinopathy (p < 0.014). Neither vitamin D2 nor vitamin D3 were associated with neuropathy. For those subjects with hypertension, dyslipidemia, retinopathy or neuropathy, comparison of highest with lowest tertiles for vitamin D2 and vitamin D3 showed no difference. CONCLUSIONS: In this Qatari cohort, vitamin D2 was associated with hypertension and dyslipidemia, whilst vitamin D3 levels were associated with diabetic retinopathy. Vitamin D2 levels were higher, whilst vitamin D3 were lower in diabetics and females, likely due to ingestion of vitamin D2 supplements.

Vitamin D Status in Egyptian Children With Allergic Rhinitis.

Objective: This study aimed to assess the serum levels of vitamin D in an Egyptian cohort of children with allergic rhinitis (AR) and to evaluate any correlation of vitamin D status with the disease severity. Patient and methods: One hundred twenty children with AR and 100 healthy children were included in our study. We studied the serum levels of vitamin D 25(OH)D and 1,25(OH)2D in all participants. The associations between vitamin D levels and clinical characteristics of AR were examined. Results: In AR group, the serum levels of calcium, (25(OH)D and 1,25(OH)2D levels were significantly lower (p < .0001, p < .001, and p < .0001, respectively) in AR children than in controls. Furthermore, the mean 25-OHD3 levels in patients with moderate/severe AR were significantly lower than those with mild AR (p < .001). We found significant negative correlations between mean 25(OH)D levels and total nasal symptom score (r = -.62, p = .002) and total immunoglobulin E levels (r = -.27, p = .013) in AR group. Conclusions: Vitamin D deficiency is a frequent finding among Egyptian children with AR when compared to the healthy group. A significant inverse association was observed between vitamin D levels and AR disease severity.

Free vitamin D levels in steroid-sensitive nephrotic syndrome and healthy controls.

INTRODUCTION: Body stores of vitamin D are measured as "total" serum 25-hydroxy vitamin D (25(OH)D). Its largest component is protein bound and lost in urine in nephrotic syndrome (NS). Our study investigates whether "free" 25(OH)D levels are a better guide to bone health and need for vitamin D supplementation in patients with steroid-sensitive NS (SSNS). METHODS: A cross-sectional study was performed in children with SSNS and healthy controls. Blood was tested for albumin, creatinine, calcium, phosphate, ALP, total and free (by direct ELISA) 25(OH)D, iPTH, and urine for protein-creatinine ratio. RESULTS: Seventy-nine NS patients (48 in relapse, 31 in remission) and 60 healthy controls were included. The levels of total 25(OH)D were significantly different (lowest in NS relapse and highest in controls) (p < 0.001). Corrected calcium and phosphate levels were normal, and there were no differences in free 25(OH)D, ALP, or iPTH levels between groups. Only total and not free 25(OH)D correlated significantly and negatively with urinary protein creatinine ratios (rs = - 0.42 vs. 0.04). Free 25(OH)D values of 3.75 and 2.85 pg/ml corresponded to total 25(OH)D levels of 20 and 12 ng/ml, respectively, in healthy controls. CONCLUSION: These results confirm that total 25(OH)D levels are low in NS and related to degree of proteinuria. However levels of free 25(OH)D, ALP, and iPTH did not change in relapse or remission in comparison with healthy controls. Our results suggest that in proteinuric renal diseases, free 25(OH)D rather than total 25(OH)D levels should be used to diagnose vitamin D deficiency and guide therapy.

[Biotin analytical interference on Siemens immunoanalysis on Dimension EXL®: impact on cardiac troponin I and total vitamin D (D2+D3) assays]. / Étude de l'interférence analytique de la biotine avec les immunoanalyses Siemens sur l'automate Dimension EXL® : impact sur les dosages de troponine I cardiaque et de vitamine D totale (D2+D3).

Several hyperthyroidism misdiagnoses cases have been recently described due to biotin intake. Biotin used in immuno-analysis assays which rely on biotin/streptavidin binding properties. In these assays, high plasmatic biotin levels can lead to major analytical interferences resulting in falsely higher (competition tests) or falsely reduced determinations (for sandwiches assays). We performed a simulation test of biotin intake with patient's samples. We studied the effect of biotin on cardiac troponin I and total vitamin D (D2+D3) assays that are using biotin-streptavidin binding on Dimension EXL®. Increasing doses of biotin were added (28 samples for each parameter) before the assays. The results evidenced a significant negative interference of biotin on cardiac troponin I determinations for concentrations of 100 ng/mL and above, with a total loss of signal for higher biotin additions. Such interference may lead to inappropriate therapeutic decisions. Positive interferences were observed on total vitamin D (D2+D3) with less impact for therapeutic decisions.

Multiple Sclerosis Patients Show Lower Bioavailable 25(OH)D and 1,25(OH)2D, but No Difference in Ratio of 25(OH)D/24,25(OH)2D and FGF23 Concentrations.

Vitamin D (VitD) insufficiency is common in multiple sclerosis (MS). VitD has possible anti-inflammatory effects on the immune system. The ratio between VitD metabolites in MS patients and the severity of the disease are suggested to be related. However, the exact effect of the bone-derived hormone fibroblast-growth-factor-23 (FGF23) and VitD binding protein (VDBP) on this ratio is not fully elucidated yet. Therefore, the aim is to study differences in total, free, and bioavailable VD metabolites and FGF23 between MS patients and healthy controls (HCs). FGF23, vitD (25(OH)D), active vitD (1,25(OH)2D), inactive 24,25(OH)D, and VDBP were measured in 91 MS patients and 92 HCs. Bioavailable and free concentrations were calculated. No difference in FGF23 (p = 0.65) and 25(OH)D/24.25(OH)2D ratio (p = 0.21) between MS patients and HCs was observed. Bioavailable 25(OH)D and bioavailable 1.25(OH)2D were lower (p < 0.01), while VDBP concentrations were higher in MS patients (p = 0.02) compared with HCs, specifically in male MS patients (p = 0.01). In conclusion, FGF23 and 25(OH)D/24.25(OH)2D did not differ between MS patients and HCs, yet bioavailable VitD concentrations are of potential clinical relevance in MS patients. The possible immunomodulating role of VDBP and gender-related differences in the VD-FGF23 axis in MS need further study.

[Vitamin D deficiency in Spanish population. Importance of egg on nutritional improvement]. / Deficiencia en vitamina D de la población española. Importancia del huevo en la mejora nutricional.

INTRODUCTION: Vitamin D is an essential nutrient whose deficiency has been associated with the risk of various chronic diseases such as osteoporosis, hypertension, cardiovascular disease, diabetes, some types of cancer and even overweight and obesity. Although vitamin D can be synthesized at the skin from exposure to sunlight, this source is not always sufficient to meet the needs. For example, the use of sunscreen or the low exposition to the sunlight limits the syntheses. In fact, studies have found that at least half of the Spanish population has vitamin D deficits. Therefore, the dietary contribution is fundamental. Although there are different foods fortified in this vitamin, few products are natural source of it, as fatty fish and eggs. However, according to different studies carried out in the Spanish population, there is a low consumption of this food group. In this way, it would be advisable to promote egg consumption among the population, since this food, in addition to having many nutrients, contains a high amount of vitamin D, which contributes to avoid the appearance of deficiencies and the consequences health consequences that this implies.

INTRODUCCIÓN: La vitamina D es un nutriente esencial cuya deficiencia se ha asociado con el riesgo de aparición de diversas enfermedades crónicas, como la osteoporosis, la hipertensión arterial, la enfermedad cardiovascular, la diabetes, algunos tipos de cáncer e incluso el padecimiento de sobrepeso y obesidad. A pesar de que la vitamina D puede sintetizarse a nivel cutáneo a partir de la exposición a la luz solar, esta fuente no es siempre suficiente para cubrir las necesidades debido al uso de cremas de protección solar y a la baja exposición que se produce durante el invierno, o, como en el caso de las personas enfermas, que salen poco a la calle o se exponen poco a la luz del sol. De hecho, estudios han constatado que al menos la mitad de la población española presenta déficit de vitamina D. Por ello, el aporte dietético es fundamental. Aunque existen diferentes alimentos fortificados con esta vitamina, son pocos los productos que son una fuente natural, entre los que se encuentran los pescados grasos y los huevos. Sin embargo, de acuerdo con diferentes estudios realizados en la población española, existe un bajo consumo de este último grupo de alimentos. De esta manera, sería recomendable fomentar el consumo de huevo entre la población, ya que este alimento, además de tener numerosos nutrientes, contiene una cantidad elevada de vitamina D, lo que contribuye a evitar la aparición de deficiencias y las consecuencias negativas para la salud que ello implica.

Sources of variation evaluation of 24,25(OH)2D levels and the ratio of 25OHD to 24,25(OH)2D in apparently healthy Chinese adults: a multicenter cross-sectional study.

24,25(OH)2D and the 25OHD/24,25(OH)2D ratio have recently been shown to be useful for screening for hypercalcemia caused by CYP24A1 mutations. However, no population-based data on 24,25(OH)2D have been published for Chinese populations, and few studies evaluated the sources of variation on 24,25(OH)2D levels and the 25OHD/24,25(OH)2D ratio. Hence, in 2018, we enrolled 1211 apparently healthy adults without systematic diseases from six representative cities in China (Beijing, Dongying, Guiyang, Urumqi, Shenzhen, and Qiqihar). 24,25(OH)2D and 25OHD levels were measured using isotope dilution liquid chromatography tandem mass spectrometry. Multiple regression analysis showed that sex contributed the most to variations in 24,25(OH)2D, 25OHD, and 25OHD/24,25(OH)2D (rp= -0.255, -0.253, and 0.141, respectively), and age also contributed to variations in 25OHD but not 24,25(OH)2D or 25OHD/24,25(OH)2D. Men had significantly higher 24,25(OH)2D and 25OHD levels than women, but had significantly lower 25OHD/24,25(OH)2D values. Individuals from Dongying had the highest 24,25(OH)2D and 25OHD values, whereas individuals from Urumqi had the lowest values. The median(2.5-97.5%) values for 24,25(OH)2D, 25OHD, and 25OHD/24,25(OH)2D were 1.2(0.36-2.65) ng/mL, 18.9(8.6-32.5) ng/mL, and 16.0 (9.8-30.8), respectively. 24,25(OH)2D was significantly correlated with 25OHD (r = 0.838, p <  0.001), and 25OHD/24,25(OH)2D was significantly negatively correlated with 24,25(OH)2D (r = -0.758, P < 0.001) and 25OHD (r = -0.310, P < 0.001). In conclusion, in this nationwide, multicenter, cross-sectional study, we evaluated the levels of 24,25(OH)2D and the 25OHD/24,25(OH)2D ratio in the Chinese population. Sex contributed the most to variations in 24,25(OH)2D, 25OHD, and 25OHD/24,25(OH)2D.

Free versus total serum 25-hydroxyvitamin D in a murine model of colitis.

Inflammatory bowel diseases (IBD) such as ulcerative colitis and Crohn's disease have been linked to vitamin D-deficiency. Using a dextran sodium sulphate (DSS)-induced model of IBD we have shown previously that mice raised on vitamin D-deficient diets from weaning have lower serum 25-hydroxyvitamin D (25OHD) levels and develop more severe colitis compared to vitamin D-sufficient counterparts. We have also shown in vitro that immune responses to 25OHD may depend on 'free' rather than total serum concentrations of 25OHD. To investigate the possible effects of free versus total 25OHD on anti-inflammatory immune responses in vivo we have studied DSS-induced colitis in wild type C57BL/6 mice raised from weaning on diets containing vitamin D2 (D2) or vitamin D3 (D3) only (both 1000 IU/kg feed). 25OHD2 has lower binding affinity for the vitamin D binding protein than 25OHD3 which results in higher levels of free 25OHD2 relative to free 25OHD3 in mice raised on a D2-only diet. Total serum 25OHD concentrations, measured by liquid chromatography-tandem mass spectrometry (LC-MS/MS), showed that D2 mice had significantly lower levels of 25OHD than D3 mice (6.85 ± 2.61 nmol/L vs. 49.16 ± 13.8 nmol/L for D2 and D3 respectively). Despite this, direct ELISA measurement showed no difference in free serum 25OHD levels between D2 and D3 mice (13.62 ± 2.26 pmol/L vs. 14.11 ± 2.24 pmol/L for D2 and D3 respectively). Analysis of DSS-induced colitis also showed no difference in weight loss or disease progression between D2 and D3 mice. These data indicate that despite D2-fed mice being vitamin D-deficient based on serum total 25OHD concentrations, these mice showed no evidence of increased inflammatory colitis disease relative to vitamin D-sufficient D3 mice. We therefore propose that free, rather than total serum 25OHD, may be a better marker of immune responses to vitamin D in vivo.

Vitamin-D2 treatment-associated decrease in 25(OH)D3 level is a reciprocal phenomenon: a randomized controlled trial.

BACKGROUND: Vitamin-D2 (D2) treatment has been associated with a decrease in 25-hydroxy (25(OH)) vitamin-D3 (D3) level, suggesting that D3 treatment would be preferred to raise total 25(OH) vitamin-D (D) level. We postulated that D2 treatment-associated decrease in 25(OH)D3 level is related to the increase in 25(OH)D level rather than being D2-specific, and thus there would be a similar D3 treatment-associated decrease in 25(OH)D2 level. METHODS: Fifty volunteers were block-randomized to 50,000 IU D2 or placebo orally once (study-1) and fifty volunteers received 50,000 IU D2 orally once and 4 days later block-randomized to 50,000 IU D3 or placebo orally once (study-2). Interventions were concealed from volunteers and research coordinators and blindly-administered. Serum 25(OH)D2 and 25(OH)D3 levels were blindly-determined at baseline and days 14, 28, 42, and 56, post-randomization by high performance liquid chromatography assay. Results of 97 participants were analyzed. Primary outcome measure was day-28 D2-associated change in 25(OH)D3 level in study-1 and D3-associated change in 25(OH)D2 level in study-2, adjusted for baseline levels. RESULTS: Mean (95% confidence interval) difference between the active and placebo arms in the decrease in day-28 25(OH)D3 (study-1) and 25(OH)D2 (study-2) levels was 13.2 (9.7 to 16.6) and 9.8 (5.2 to 14.4) nmol/L, respectively. Corresponding differences at day-56 were 10.8 (6.8 to 14.8) and 1.7 (- 7.6 to 11.1) nmol/L, respectively. The difference between the placebo and active arms in area-under-the-curve at day-28 (AUC28) and day-56 (AUC56) were 262.3 (197.8 to 326.7) and 605.1 (446.3 to 784.0) for 25(OH)D3 (study-1) and 282.2 (111.2 to 453.3) and 431.2 (179.3 to 683.2) nmol.d/L for 25(OH)D2 (study-2), respectively. There were significant correlations between day-28 changes in 25(OH)D2 and 25(OH)D3 levels in study-1 (rho = - 0.79, p < 0.001) and study-2 (rho = - 0.36, p = 0.01), and between day-28 changes in 25(OH)D2 level and baseline 25(OH)D level in study-2 (rho = - 0.42, p = 0.003). CONCLUSIONS: Compared to placebo, D3 treatment is associated with a decrease in 25(OH)D2 level similar in magnitude to D2-treatment associated decrease in 25(OH)D3 level; however, the D3-placebo difference in 25(OH)D2 level is shorter-lasting. Changes in 25(OH)D2 and 25(OH)D3 levels are correlated with each other and with baseline 25 (OH) D levels, suggesting a common regulatory mechanism. TRIAL REGISTRATION: ClinicalTrial.gov identifier: NCT03035084 (registered January 27, 2017).

Rapid liquid chromatography-tandem mass spectrometry method for determination of 24,25(OH)2D and 25OHD with efficient separation of 3-epi analogs.

This study establishes and validates a rapid method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) without derivatization steps to simultaneously measure of 24,25(OH)2D2, 24,25(OH)2D3, 25OHD2, and 25OHD3, while efficiently separating the 3-epi analogs. Samples were prepared by precipitation and liquid-liquid extraction. The linearity, precision, accuracy, recovery and matrix effect of the method were thoroughly evaluated according to the Clinical & Laboratory Standards Institute guidelines. Additionally, the four vitamin D metabolites in the serum of 38 apparently healthy Chinese volunteers were evaluated. The total analysis time was 8.0 min, with efficient separation of 3-epi 24,25(OH)2D3 and 3-epi 25OHD3, without interference from isomers such as 23,25(OH)2D3 or 1,25(OH)2D2, 1,25(OH)2D3. Good reproducibility was obtained for all four metabolites with within-run coefficient variations (CVs) of 4.07%-6.55%, 4.26%-7.84%, 2.46%-7.21%, and 4.90%-6.87% for 25OHD3, 25OHD2, 24,25(OH)2D3, and 24,25(OH)2D2, respectively, and the total CVs were 4.29%-6.64%, 6.14%-7.84%, 4.33%-7.21%, 5.82%-9.90%, respectively. The limit of quantification was 0.625 ng/mL for 25OHD3 and 25OHD2, and 0.5 ng/mL for 24,25(OH)2D3 and 24,25(OH)2D2. The relative bias of the LC-MS/MS method compared to the certified results of SRM 972a for 25OHD3, 25OHD2 and 24,25(OH)2D3 was -2.21% to 1.01%, 3.38% to 6.73%, and -7.72% to -3.9%, respectively. The mean±SD values for 25OHD, 24,25(OH)2D and 25OHD/24,25(OH)2D in the volunteers were 13.5±4.4 ng/mL(range:7.6-27.5 ng/mL), 0.84±0.42 ng/mL (range:0.26-2.1 ng/mL), and 18±7(range:8-37), respectively. Thus, a simple, precise LC-MS/MS method for appropriate retention and separation of vitamin D metabolites and their epi analogs was developed.