Search

Background: Deficiency in vitamin D is widely prevalent around the world. Oral vitamin D supplementation is suggested for older adults to sustain appropriate 25-hydroxyvitamin D (25(OH)D) levels throughout the year. At present, cholecalciferol (vitamin D3) and ergocalciferol (vitamin D2) are the most commonly used compounds. Supplementation with calcifediol (25OHD3) rather than vitamin D itself should also be considered for the treatment. We performed a systematic review of the literature with a meta-analysis to assess the effects of cholecalciferol (vitamin D3) compared to calcifediol (25OHD3) on increasing serum 25(OH)D levels., Methods: A search of online databases was performed electronically for all relevant observational published population-based studies until November 2023, without geographical restrictions. We included studies that directly compared the effects of cholecalciferol and calcifediol on increasing concentrations of serum 25(OH)D. Only papers in English or French languages were considered. Records were screened and data were retrieved through a standardized extraction process., Results: Seventeen studies including 1575 participants were reviewed. Twelve intervention trials showed that, in spite of the dosage or the frequency of administration, calcifediol supplementation was more efficacious in raising serum 25(OH)D concentrations compared with cholecalciferol. Two studies showed that calcifediol and cholecalciferol were identically potent. According to three studies, cholecalciferol was more effective than calcifediol in raising 25(OH)D concentrations. A meta-analysis including randomized controlled trials (RCTs) and non-randomized trials revealed that calcifediol supplementation had a better impact on elevating serum 25(OH)D concentrations compared with the effect of cholecalciferol., Conclusion: This meta-analysis suggests that calcifediol is more effective in increasing serum 25(OH)D concentrations compared to cholecalciferol. Consequently, calcifediol may emerge as the preferred option for supplementation., (© 2024. The Author(s), under exclusive licence to Springer Nature Limited.)

Background/objectives: To investigate the correlation between serum 25-hydroxyvitamin D (25(OH)D) and brachial-ankle pulse wave velocity (baPWV) and mortality among peritoneal dialysis (PD) patients.Subjects/methods: We retrospectively reviewed the data of 269 PD patients in our center from January 1, 2013, to December 31, 2018. Subjects were divided into groups according to serum 25(OH)D level based on a cut-off of 20 ng/ml. The general linear regression model was employed to explore the correlation between 25(OH)D and baPWV. The correlation between 25(OH)D and mortality was examined in Cox proportional hazards models.Results: The mean (±SD) concentration of serum 25(OH)D was 17 (±7.2) ng/ml. Using linear regression analysis, and after adjusting for possible confounders, serum 25(OH)D concentration was found to be negatively associated with baPWV(β = -0.35, p < 0.001). Multivariate analysis showed that lower 25(OH)D level was significantly associated with higher total mortality in PD patients(< 20 ng/ml vs. ≥ 20 ng/ml; HR, 2.27; 95% CI, 1.04-4.93; P = 0.04)(as a continuous variable; HR, 0.94; 95% CI, 0.90-0.98; P = 0.01).Conclusions: Serum 25(OH)D concentration was a significant factor associated with baPWV and mortality among patients with PD. Further studies with larger sample sizes will be needed to confirm this correlation. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to determine the influence of polymorphisms in some key gene actors of the vitamin D (vitD) metabolic pathway on supplementation efficacy. Methods: In total, 245 healthy participants were recruited from occupational medicine service in Sahloul University Hospital with vitD deficiency [25(OH)D ≤ 30 ng/ml]. After giving an informed consent, all participants were asked to complete a generalized questionnaire and to follow a detailed personalized supplementation protocol. Genetic study was performed by PCR-RFLP for 15 single nucleotide polymorphisms (SNPs) belonging to DBP, CYP2R1, CYP27B14, CYP24A1 and VDR genes. Statistical study was carried out with SPSS23.0. Results: Among the studied SNPs, non-response was significantly associated with variant alleles of rs4588 (OR* = 11.51; p < 0.001), rs10766197 (OR* = 6.92; p = 0.008) and rs12794714 (OR* = 5.09; p = 0.004). These three SNPs contributed in 18.8% in response variability with rs4588 being the most influential (10.3%). There was a significant linear negative correlation between baseline 25(OH)D and post supplementation 25(OH)D concentration (r = −0.437; p < 0.001) as well as a linear negative association between the increase in 25(OH)D concentration and GRS (GRS: genetic risk score = the sum of risk alleles) (r = −0.149; p = 0.033). Conclusions: DBP-rs4588, CYP2R1-rs10766197 and rs12794714 variants are associated with variations in serum 25(OH)D concentrations and efficacy of response to vitD supplementation in Tunisian adults. Taking into account these variations can help to better adapt vitD intake to ensure a higher response to supplementation. [ABSTRACT FROM AUTHOR]

It remains debatable whether vitamin D plays any role as a risk factor for type 1 diabetes mellitus (T1DM). We have summarized the effect of circulating 25-hydroxy vitamin D [25(OH)D] concentration on the risk of developing T1DM via a dose-response meta-analysis. We undertook a database search on PubMed, Embase, and Cochrane Library from inception to January 2020. A meta-analysis based on random-effects model was applied. Subgroup analysis and meta-regression were performed to inspect the source of heterogeneity. Dose-response data were examined using the generalized least squares trend estimation method. This study was registered with the PROSPERO (ID: CRD42020166174). In total, 16 studies including 10,605 participants (3913 case patients) were included. The pooled odds ratios (OR) and 95% confidence intervals (95% CI) for the highest versus the lowest 25(OH)D concentration was 0.39 (0.27, 0.57), with a high heterogeneity (I2 = 76.7%, P < 0.001). Meta-regression analysis identified latitude (P = 0.02), adjustment for gender (P = 0.001), and 25(OH)D stratification (P < 0.001) as sources of heterogeneity. Furthermore, the nonlinear dose-response analysis determined the OR (95% CI) of T1DM to be 0.91 (0.90, 0.93) per 10 nmol/L increase in the 25(OH)D concentration. A 'U'-shaped association was found between serum 25(OH)D concentration and risk of T1DM. The present study highlights the significant inverse association between the circulating 25(OH)D concentration and the risk of T1DM. [ABSTRACT FROM AUTHOR]

Background/objectives: Our objective was to evaluate the degree of tracking for serum levels of 25-hydroxyvitamin D [25(OH)D] over time, by using data from three previously conducted surveys of the Tromsø study collected in the years 1994/1995 (Tromsø 4), 2007/2008 (Tromsø 6), and 2015/2016 (Tromsø 7).Subjects/methods: Subjects with valid 25(OH)D measurements in all three surveys were included. 25(OH)D z-scores were used to adjust for seasonal variation. Z-scores and sextiles were used to illustrate tracking of 25(OH)D.Results: 1702 subjects (572 males, 1130 females) fulfilled the inclusion criteria. Median (5th, 95th percentiles) age for these subjects was 55 (33, 65) years in Tromsø 4, and mean (SD) 25(OH)D levels were 57 (18) nmol/L, 59 (19) nmol/L, and 72 (21) nmol/L for Tromsø 4, Tromsø 6, and Tromsø 7, respectively. There was significant tracking of serum 25(OH)D over the 21 years period between the surveys of the Tromsø study. The correlation coefficient r between 25(OH)D z-scores from Tromsø 4 and Tromsø 6 was 0.40, and declined to 0.29 for the correlation between Tromsø 4 and Tromsø 7. Twenty-six percent of the subjects in the lowest 25(OH)D z-score sextile in Tromsø 4 were in the three highest sextiles of 25(OH)D in Tromsø 7. Similarly, 35% of those in the highest sextile in Tromsø 4 were in the lowest three sextiles in Tromsø 7.Conclusions: The degree of tracking for serum 25(OH)D declines over time, and the use of a single serum 25(OH)D measurement as an indicator of the vitamin-D status is questionable if used in long-lasting observational studies. [ABSTRACT FROM AUTHOR]

Objectives: To study the effect of vitamin D supplementation and the impact of summer season on serum 25-hydroxyvitamin D (S-25(OH)D) in Finnish 9-15-y-old girls. Design: Three-year follow-up study with vitamin D[sub 2] supplementation using D[sub 2] 10 µg daily from October to January for the first and from October to February for the second winter as well as 20 µg daily from October to March for the third winter. Setting: Paavo Nurmi Centre, University of Turku, Turku, Finland. Subjects: A total of 171 female volunteers aged 9-15 y. Methods: Vitamin D and calcium intakes were estimated by a semi-quantitative food frequency questionnaire (FFQ). S-25(OH)D was measured by radioimmunoassay. Results: The median daily dietary intakes of vitamin D and calcium were 3.8 µg (interquartile range (IQR) 2.7-5.0) and 1451 mg (IQR 1196-1812), respectively, over 3 y. The prevalence of severe hypovitaminosis D (S-25(OH)D < 20 nmol/I) was 14% and of moderate hypovitaminosis D (20 nmol/I ≤ S-25(OH)D ≤ 37.5 nmol/I) 75% at baseline in winter. None of the participants had severe hypovitaminosis D in summer. The effect of 10 µg of D[sub 2] daily was insufficient to raise S-25(OH)D from baseline. The daily supplementation of 20 µg of D[sub 2] increased S-25(OH)D significantly in wintertime compared with the nonsupplement users (to 45.5 vs 31.8 nmol/l; P < 0.001 ). None Of the subjects with vitamin D[sub 2] supplementation approximately 20 µg daily had severe hypovitaminosis D; however, 38% of those participants had moderate hypovitaminosis D at 36 months. Sun exposure in summer raised mean S-25(OH)D to 62.0 nmol/L Both the daily supplementation of approximately 20 µg of D[sub 2] and summer sunlight exposure had more effect on those who had severe hypovitaminosis than those who had a normal vitamin D status (increase of 24.2 vs 0.9 nmol/I (P < 0.001 ), and 38.8 vs 18.2 nmol/I (P < 0.001 ), respectively). Conclusion: Vitamin D... [ABSTRACT FROM AUTHOR]

Background/objectives: In observational, but not interventional, studies there are strong associations between serum 25-hydroxyvitamin D (25(OH)D) and serum lipids. The purpose of the present study was to examine potential causes of this association.Subjects/methods: A total of 17,411 subjects participating in the seventh survey of the Tromsø Study were included in the cross-sectional study; 5384 subjects who participated in both the sixth and seventh survey were included in the longitudinal study; 2365 subjects who participated in both the fourth and seventh survey were included in the genetic study; and 479 subjects with impaired glucose tolerance were included in the vitamin D binding protein (DBP) analyses.Results: For serum 25(OH)D, there were strong and positive associations with LDL-, HDL-, and total-cholesterol, and a negative association with triglycerides that remained after adjustment for gender, age, BMI, diet, supplements, and lifestyle factors. These associations were seen in winter as well as summer. Except for serum cholesterol, change of season for blood sampling did not affect lipid levels. However, when analyzing separately, subjects with low or no intake of vitamin D supplements, fish oil and fat fish, only the association between 25(OH)D and HDL-cholesterol remained significant. Serum DBP or single-nucleotide polymorphisms related to 25(OH)D had no relation to lipid levels.Conclusions: The associations between 25(OH)D and lipids (except for HDL-cholesterol) can be explained by known confounding factors. However, for HDL-cholesterol, the cause of the association with 25(OH)D still remains unknown. [ABSTRACT FROM AUTHOR]

Short telomere length is associated with chronic diseases and decreased lifespan. Vitamin D and its binding protein (DBP) may maintain telomeres through anti-inflammatory actions, yet the role of vitamin D on telomere length is uncertain, especially in children. We assessed the cross-sectional associations of plasma 25-hydroxy vitamin D (25(OH)D) and DBP with leukocyte telomere length (LTL) in a group of 447 children ages 5-12 years from the Bogotá School Children Cohort. We compared the distribution of age-standardized LTL (z-score) between 25(OH)D categories and between DBP quartiles overall and by sex. Overall, 25(OH)D was not significantly associated with LTL. Nonetheless, among boys, 25(OH)D < 50 nmol/L was related to an adjusted 0.36 shorter LTL z-score (95% CI: -0.71, -0.01; P = 0.046) compared with 25(OH)D ≥ 75 nmol/L. There was no association among girls. DBP was not significantly related to LTL. Intervention studies are warranted to determine whether increasing vitamin D status enhances telomere length. [ABSTRACT FROM AUTHOR]

Vitamin D deficiency and insufficiency has become a pandemic health problem with a consequent increase of requests for determining circulating levels of 25-hydroxyvitamin D [25(OH)D]. However, the analytical performance of these immunoassays, including radioimmunoassay and ELISA, is highly variable, and even mass spectrometric methods, which nowadays serves as the gold standard for the quantitatively determination of 25(OH)D, do not necessarily produce comparable results, creating limitations for the definition of normal vitamin D status ranges. To solve this problem, great efforts have been made to promote standardization of laboratory assays, which is important to achieve comparable results across different methods and manufacturers. In this review, we performed a systematic analysis evaluating critically the advantages and limits of the current assays available for the measure of vitamin D status, i.e., circulating 25(OH)D and its metabolites, making suggestions that could be used in the clinical practice. Moreover, we also suggest the use of alternatives to blood test, including standardized surveys that may be of value in alerting health-care professionals about the vitamin D status of their patients. [ABSTRACT FROM AUTHOR]

Background: Vitamin D is an important regulator of calcium. Mendelian randomization (MR) studies exclusively focused on the circulating total 25-hydroxyvitamin D (25(OH)D) as a biomarker of vitamin D status, and have found the causal association between 25(OH)D and the risk of multiple sclerosis (MS). However, it currently remains unclear about the causal association of the 25(OH)D subtypes including 25(OH)D3 and C3-epi-25(OH)D3, as well as calcium with the risk of MS. Methods: We performed a two-sample MR study to evaluate the causal association of circulating total 25(OH)D, 25(OH)D3, C3-epi-25(OH)D3, and calcium with the risk of MS using large-scale genome-wide association studies (GWAS) datasets from total 25(OH)D (n = 417,580), 25(OH)D3 (n = 40,562), C3-epi-25(OH)D3 (n = 40,562), calcium (n = 305,349), and MS (14,802 MS and 26,703 controls). We selected five MR methods including inverse-variance weighted (IVW), simple median, weighted median, MR-Egger, MR-PRESSO (Mendelian Randomization Pleiotropy Residual Sum and Outlier), and contamination mixture method. Results: IVW showed that the genetically increased circulating 25(OH)D level (OR = 0.81, 95% CI: 0.70–0.94, P = 4.00E-03), circulating 25(OH)D3 level (OR = 0.85, 95% CI: 0.76–0.95, P = 5.00E-03), and circulating C3-epi-25(OH)D3 level (OR = 0.85, 95% CI: 0.74–0.98, P = 2.30E-02) were causally associated with reduced risk of MS. However, IVW showed no causal association between circulating calcium level and the risk of MS with OR = 2.85, 95% CI: 0.42–19.53, P = 2.85E-01. Conclusions: Our current findings together with evidence from other MR studies support the use of vitamin D but not calcium supplementation for the prevention of MS. [ABSTRACT FROM AUTHOR]

Objectives: To determine the prevalence and risk factors of vitamin D deficiency in pregnant women and their infants at birth (cord blood) and at six months of age in Turkey, as well as to assess the compliance rates of families with vitamin D supplementation. Methods: Serum 25-hydroxyvitamin D [25(OH)D] level was measured of the mothers before delivery and of the infants both at birth (cord blood) and at six months of age. Infants who received and did not take regular vitamin D supplements were compared in terms of 25(OH) levels. Independent risk factors were determined by multiple logistic regression analysis. Results: The study included a total of 140 pregnant women and their infants. Vitamin D deficiency was found in 95.7% of the mothers. The prevalence of vitamin D deficiency was 87.1% in infants at birth but decreased to 5.8% at sixth month. 65.7% of infants received vitamin D supplements regularly. Despite regular vitamin D use, it was determined that 2.2% of the infants in the supplementation compliant group had vitamin D deficiency. Maternal age, maternal education level, and the number of siblings were determined to be determining factors on infants' 25(OH)D levels at six months (p < 0.05). Conclusions: In Turkey, vitamin D deficiency still exists in both pregnant women and infants. Healthcare professionals and the public need to be more educated about the importance of regular supplementation. Serum 25(OH)D levels of infants should be tested periodically and personalized vitamin D supplementation planning is required based on test results. [ABSTRACT FROM AUTHOR]

Background/objectives: Vitamin D deficiency remains a global public health issue, particularly in minority ethnic groups. This review investigates the vitamin D status (as measured by 25(OH)D and dietary intake) of the African-Caribbean population globally.Subjects/methods: A systematic review was conducted by searching key databases (PUBMED, Web of Science, Scopus) from inception until October 2019. Search terms included 'Vitamin D status' and 'African-Caribbean'. A random effects and fixed effects meta-analysis was performed by combining means and standard error of the mean.Result: The search yielded 19 papers that included n = 5670 African-Caribbean participants from six countries. A meta-analysis found this population to have sufficient (>50 nmol/L) 25(OH)D levels at 67.8 nmol/L, 95% CI (57.9, 7.6) but poor dietary intake of vitamin D at only 3.0 µg/day, 95% CI (1.67,4.31). For those living at low latitudes 'insufficient' (as defined by study authors) 25(OH)D levels were found only in participants with type 2 diabetes and in those undergoing haemodialysis. Suboptimal dietary vitamin D intake (according to the UK recommended nutrient intake of 10 µg/day) was reported in all studies at high latitudes. Studies at lower latitudes, with lower recommended dietary intakes (Caribbean recommended dietary intake: 2.5 µg/day) found 'sufficient' intake in two out of three studies.Conclusions: 25(OH)D sufficiency was found in African-Caribbean populations at lower latitudes. However, at higher latitudes, 25(OH)D deficiency and low dietary vitamin D intake was prevalent. [ABSTRACT FROM AUTHOR]

Objectives: Arterial stiffness (AS), one of the complications of diabetes, associated with many metabolic factors. This study aimed to investigate the association between 25-hydroxyvitamin D(25(OH)D) and AS in type 2 diabetes mellitus (T2DM).Methods: We identified 1335 diabetic patients from the Department of Endocrinology, Shanghai Tenth People's Hospital. Finally, 603 T2DM patients were included in the study. They were divided into two groups: AS group (baPWV ≥ 15,500 cm/s) and the control group (baPWV < 1550 cm/s).Results: (1) Heart rate (HR) and systolic pressure (SBP) were higher while body weight and body mass index (BMI) were smaller in AS group than the control group (all P < 0.05). (2) Compared to patients without AS, patients with AS showed lower 25(OH)D and higher rate of 25(OH)D deficiency (42 ± 16 vs. 45 ± 17 mol/l, 68% vs. 64%, all P < 0.05). (3) BaPWV was negatively associated with 25(OH)D (r = -0.12, P = 0.004), while positively associated with age, duration of diabetes, HR, SBP, and low-density lipoprotein cholesterol and negatively associated with body weight and BMI (all P < 0.05). (4) Multiple linear regression showed that 25(OH)D was the negatively influencing factor of baPWV (β = -2.2, P = 0.01). Logistic regression showed that age and SBP were risk factor of AS (OR:1.07, 95% CI: 1.05-1.10, P < 0.001; OR:1.03, 95% CI: 1.02-1.04, P < 0.001) while 25(OH)D was protective factor of AS (OR:0.987, 95% CI: 0.976-0.998, P = 0.024).Conclusions: T2DM patients with AS had lower 25(OH)D and higher rate of 25(OH)D deficiency. There was a negative relationship between 25(OH)D and AS assessed by baPWV. [ABSTRACT FROM AUTHOR]

Background/objectives: Optimal doses of vitamin D (VitD) supplement in different populations are unclear. We aim to evaluate the relationship between VitD supplementation and post-intervention serum 25-hydroxyvitamin D [25(OH)D] concentration, to provide a recommended dosage of VitD for achieving an optimal 25(OH)D concentration for different populations.Subjects/methods: Literature search was conducted in Embase, etc. Randomized controlled trials about VitD supplemental intakes and their effect on 25(OH)D concentration were enrolled. The effect on 25(OH)D concentration between different supplementation doses in each population group was compared by meta-analysis. Multivariate meta-regression model is utilized to establish reference intake dosage of VitD.Results: A total of 136 articles were included about children (3-17 years), adults (18-64 years), postmenopausal women, the elderly ( >64 years), pregnant, or lactating women. Overall, intervention groups obtained higher 25(OH)D concentration than controls and there was obvious dose-response effect between intake dose and 25(OH)D concentration. Baseline 25(OH)D concentration and age were significant indicators for 25(OH)D concentration. To reach sufficient 25(OH)D concentration (75 nmol/L), the recommended VitD supplemental intakes was 1340 and 2250 IU/day for children and pregnant women, 2519 and 797 IU/day for European adults aged 18-64 and 65-85 years, 729, 2026, and 1229 IU/day for adults in North America, Asia and Middle East and Africa, respectively.Conclusions: Regional- and age-specific recommended dosages of VitD supplements for population to achieve optimal 25(OH)D concentrations have been suggested. [ABSTRACT FROM AUTHOR]

Background/objectives: To provide age- and sex-specific percentile curves of serum 25-hydroxyvitamin D (25(OH)D) by determinants from 3-<15 year-old European children, and to analyse how modifiable determinants influence 25(OH)D.Subjects/methods: Serum samples were collected from children of eight European countries participating in the multicenter IDEFICS/I.Family cohort studies. Serum 25(OH)D concentrations were analysed in a central lab by a chemiluminescence assay and the values from 2171 children (N = 3606 measurements) were used to estimate percentile curves using the generalized additive model for location, scale and shape. The association of 25(OH)D with time spent outdoors was investigated considering sex, age, country, parental education, BMI z score, UV radiation, and dietary vitamin D in regressions models.Results: The age- and sex-specific 5th and 95th percentiles of 25(OH)D ranged from 16.5 to 73.3 and 20.8 to 79.3 nmol/l in girls and boys, respectively. A total of 63% had deficient (<50 nmol/l), 33% insufficient (50-<75 nmol/l) and 3% sufficient (≥75 nmol/l) levels. 25(OH)D increased with increasing UV radiation, time spent outdoors, and vitamin D intake and slightly decreased with increasing BMI z score and age. The odds ratio (OR) for a non-deficient 25(OH)D status (reference category: deficient status) by one additional hour spent outdoors was 1.21, 95% CI [1.12-1.31], i.e., children who spent one more hour per day outdoors than other children had a 21% higher chance of a non-deficient than a deficient status.Conclusion: A majority of children suffer from deficient 25(OH)D. UV radiation, outdoor time, and dietary vitamin D are important determinants of 25(OH)D. [ABSTRACT FROM AUTHOR]

Background: Mendelian randomization (MR) analyses from the West provide evidence that obesity causes lower 25-hydroxyvitamin D [25(OH)D]. As Asian populations are prone to metabolic disorders at a lower body mass index (BMI), whether the association remains in Asian is unclear. We studied whether obesity causes vitamin D deficiency using MR analysis in Chinese.Methods: We used data from the Guangzhou Biobank Cohort Study. A genetic score including seven BMI-related single-nucleotide polymorphisms (n = 15,249) was used as the instrumental variable (IV) for BMI. Two-stage least square regression and conventional multivariable linear regression in 2,036 participants with vitamin D data were used to analyze association of BMI with vitamin D.Results: Proportion of variation explained by the genetic score was 0.7% and the first stage F-statistic for MR analysis was 103. MR analyses showed that each 1 kg/m2 higher BMI was associated with lower 25(OH)D by -2.35 (95% confidence interval (CI) -4.68 to -0.02) nmol/L. In conventional multivariable linear regression, higher BMI was also associated with lower 25(OH)D (β = -0.26 nmol/L per 1 kg/m2 increase in BMI, 95% CI -0.46 to -0.06). Sensitivity analyses using two-sample IV analysis and leave-one-out method showed similar results.Conclusion: We have first shown by MR and conventional multivariable linear regression that higher BMI causes vitamin D deficiency in Chinese. Our findings highlight the importance of weight control and suggest that vitamin D supplementation may be needed in individuals with overweight or obesity. [ABSTRACT FROM AUTHOR]

Background/objectives: To assess the prevalence of vitamin D deficiency in Dutch athletes and to define the required dosage of vitamin D3 supplementation to prevent vitamin D deficiency over the course of a year.Subjects/methods: Blood samples were collected from 128 highly trained athletes to assess total 25(OH)D concentration. Of these 128 athletes, 54 male and 48 female athletes (18-32 years) were included in a randomized, double blind, dose-response study. Athletes with either a deficient (<50 nmol/l) or an insufficient (50-75 nmol/l) 25(OH)D concentration were randomly assigned to take 400, 1100 or 2200 IU vitamin D3 per day orally for 1 year. Athletes who had a total 25(OH)D concentration above 75 nmol/l at baseline continued with the study protocol without receiving vitamin D supplements. Serum total 25(OH)D concentration was assessed every 3 months, as well as dietary vitamin D intake and sunlight exposure.Results: Nearly 70% of all athletes showed an insufficient (50-75 nmol/l) or a deficient (<50 nmol/l) 25(OH)D concentration at baseline. After 12 months, serum 25(OH)D concentration had increased more in the 2200 IU/day group (+50±27 nmol/l) than the sufficient group receiving no supplements (+4±17 nmol/l; P<0.01) and the 1100 IU/day group (+25±23 nmol/l; P<0.05). Supplementation with 2200 IU/day vitamin D resulted in a sufficient 25(OH)D concentration in 80% of the athletes after 12 months.Conclusions: Vitamin D deficiency is highly prevalent in athletes. Athletes with a deficient or an insufficient 25(OH)D concentration can achieve a sufficient 25(OH)D concentration within 3 months by taking 2200 IU/day. [ABSTRACT FROM AUTHOR]

Over the past two decades, many studies reported the benefits of higher 25-hydroxyvitamin D [25(OH)D] concentrations for nonskeletal effects. Researchers found significant benefits in reducing risk of acute respiratory tract infections, many types of cancer, type 2 diabetes mellitus, premature death, and adverse pregnancy and birth outcomes. In addition, 25(OH)D concentrations are low for various reasons in several categories of people, including the obese, those with dark skin living at higher latitudes, the elderly, and those who do not eat much eggs, fish, meat, or vitamin D fortified milk. Measuring 25(OH)D concentrations is one way to both increase the awareness of vitamin D's importance in maintaining good health and to encourage vitamin D supplementation or increased solar ultraviolet-B exposure to sustain well-being throughout life by reducing disease incidence. Although 20 ng/ml seems adequate to reduce risk of skeletal problems and acute respiratory tract infections, concentrations above 30 ng/ml have been associated with reduced risk of cancer, type 2 diabetes mellitus, and adverse pregnancy and birth outcomes. Thus, judicious testing of 25(OH)D concentrations could reduce disease incidence and make treatment expenditures more cost-effective. [ABSTRACT FROM AUTHOR]

Background: Vitamin D is critical for skeletal health, and is increasingly associated with other pathologies encompassing gastrointestinal, immunological and psychological effects. A significant proportion of the population exhibits suboptimal levels of vitamin D, particularly in Northern latitudes in winter. Supplementation is advocated, but few data are available on achievable or typical rates of change. There has been considerable interest in the potential use of sublingual sprays for delivery of nutrient supplements, but data on efficacy remain sparse.Methods: A randomised, placebo-controlled, three-arm parallel design study was conducted in healthy volunteers (n = 75) to compare the rate of change of vitamin D status in response to vitamin D3 (3000 IU/day) supplementation in capsule and sublingual spray preparations over a 6-week period between January and April 2017. Blood 25(OH)D concentrations were measured after day 0, 3, 7, 14, 21 and 42 days of supplementation with 3000 IU per diem.Results: Baseline measurements show 25(OH)D deficiency (<30 nmol/l), insufficiency (31-46 nmol/l) and sufficiency (> 50 mmol/l) in 14.9, 44.6 and 40.5% of the participants, respectively. There was a significant elevation in blood concentrations of 25(OH)D in both of the treatment arms (capsule p = 0.003, spray p = 0.001) compared with control. The capsule and spray were equally efficacious. The rate of change ranged from 0.69 to 3.93 (capsule) and 0.64 to 3.34 (spray) nmol/L day with average change in blood 25(OH)D levels of 2 nmol/l/day. Rates followed a simple normal distribution in the study population (ks = 0.94 and 0.82 for capsule and spray, respectively). The data suggest that rates of change are higher in individuals with lower levels of 25(OH)D.Conclusions: A sublingual vitamin D spray is an effective mode of delivery for supplementation in a healthy population. The data provide reference values and ranges for the rate of change of 25(OH)D for nutrikinetic analyses. [ABSTRACT FROM AUTHOR]

Background/objectives: Familial correlation of serum 25-hydroxyvitamin D concentration (25(OH)D) was reported in twin- or parent-offspring studies. However, data on relative contribution of environmental factors on familial clustering of 25(OH)D in extended families are limited.Subjects/methods: We performed cross-sectional study using data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2008-2012. Familial correlations of 25(OH)D were estimated in 28,551 subjects from 10,882 families. The variance component method was used to assess the relative contribution of additive genetic or environmental contributions to the variation in 25(OH)D level. Logistic regression models with interaction term were built to evaluate the differential influence of parental vitamin D status on the adolescents and adults offspring.Results: Mean serum 25(OH)D concentration of subjects was 44.6 nmol/L (vitamin D insufficiency (30-50 nmol/L), 51%; vitamin D deficiency ( < 30 nmol/L), 17%). Familial clustering explained 40% of the total variation in 25(OH)D. In the variance component model, 4%, 39%, and 57% of the variation in serum 25(OH)D level was attributed to additive genetic, common shared environmental, and individual environmental factors, respectively. The odds of vitamin D deficiency in offspring with both parents with vitamin D deficiency compared with those with both parents with sufficient vitamin D levels was greater in adolescents ( < 19 years) than in adults ( ≥ 19 years) (odds ratio = 41.1 vs. 12.5; p for interaction = 0.03).Conclusions: We found a familial clustering of vitamin D deficiency in a large family-based cohort. Parental influence on vitamin D status of offspring was greater in adolescents than in adults. [ABSTRACT FROM AUTHOR]

Background: Vitamin D [25(OH)D] is essential for normal bone development and maintenance. Furthermore, its deficiency has been associated with obesity, cardiovascular diseases, insulin resistance, autoimmune diseases, and certain cancers.Objective: To determine the incidence of serum 25(OH)D deficiency (<20 ng/ml) among apparently healthy Chilean children (4-14 years old) from three Chilean geographic areas during May-September 2018.Materials and Methods: Serum 25(OH)D levels were measured by a competitive protein-binding ELISA assay in 1134 children, and correlations between serum 25(OH)D levels, BMI, and geographic area were calculated. Individuals were grouped according to their serum 25-hydroxyvitamin D levels (ng/ml): severe deficiency: <5; moderate deficiency: 5-10.9; mild deficiency: 11-20.9; insufficiency: 21-29.9 and sufficiency: 30-100.Results: We found 80.4% of children had serum 25(OH)D deficiency, with 1.7% severe, 24.6% moderate, and 54.1% mild. In the three cities, the percentage of serum 25(OH)D deficit was increased when comparing overweight or obesity with a healthy weight. Additionally, an interaction effect was observed between geographic area, nutritional status, and serum 25(OH)D levels using the factorial ANOVA test (p = 0.038). In Antofagasta, there were more overweight children and also a higher percentage of children with VitD deficiency (<30 ng/ml) compared to Santiago or Concepción.Conclusion: This study revealed a high prevalence of serum 25(OH)D deficiency in children between 4 and 14 years old in Chile (80.4%) during May-September 2018. Obese and overweight children had the highest prevalence of serum 25(OH)D deficiency. [ABSTRACT FROM AUTHOR]

We examined the association of baseline serum 25-hydroxyvitamin D (25(OH)D) with change in weight and total body fat in a cohort of community-dwelling older adults from Southern Germany. A total of 735 participants of the population-based KORA-Age Study (2009-2012), aged 65-90 years, were followed for 2.9±0.1 years. Body fat was assessed with bioelectrical impedance analysis. Linear and multinomial logistic models, adjusted for baseline covariables, were used to examine the association of 25(OH)D with percentage weight and body fat change during follow-up. 25(OH)D levels were not associated with overall weight change or body fat loss. Higher 25(OH)D levels were associated with a lower likelihood of having gained >3% of body fat in women but not in men. As we cannot exclude residual confounding by outdoor physical activity and diet, our results are not sufficient to support a causal role of 25(OH)D in the etiology of obesity in Caucasian older adults. [ABSTRACT FROM AUTHOR]

Background/objectives: Evidence is lacking on how variation in vitamin D concentrations during gestation affects perinatal outcomes. Therefore, we evaluated the association between vitamin D serum concentrations during pregnancy and neonatal outcomes.Methods: A prospective cohort of 180 healthy Brazilian pregnant women was followed and plasma 25-hydroxyvitamin [25(OH)D, nmol/L] was measured at 5-13 (baseline), 20-26 and 30-36 gestational weeks. Birth weight (BW), birth length (BL), BW z-scores, BL z-scores, first minute Apgar, small for gestational age (SGA), large for gestational age (LGA) and preterm birth were the outcomes. Multiple linear and Poisson regression models were estimated. Best linear unbiased prediction of random coefficients model was used to determine the association between the mean rate of change in vitamin D during pregnancy concentrations and neonatal outcomes.Results: Mean (SD) BW was 3300 (600) g, BW z-score 0.34 (1.11), BL 49.3 (3.3) cm, BL z-score 0.44 (1.5), and first minute Apgar score 8.2 (1.4). Prevalence of SGA, LGA and preterm birth were 6%, 18% and 13%, respectively. 25(OH)D was directly associated with the risk of preterm birth at all trimesters. Incidence-rate ratios were 1.02, 1.05 and 1.04 for the 1st, 2nd and 3rd trimester, respectively. Mean rate of change during pregnancy in 25(OH)D was directly associated with BW z-score (β: 0.36, 95% CI 0.07; 0.65), LGA risk (IRR: 1.97, 95% CI 1.07; 3.63) and preterm birth (IRR: 7.35, 95% CI 2.99; 18.07).Conclusions: Mean 25(OH)D rate of change during pregnancy was directly associated with BW z-scores, and increased LGA and preterm birth risk. [ABSTRACT FROM AUTHOR]

Background: The gastrointestinal microbiota is emerging as an important mediator in intestinal metabolism, such as vitamin D absorption.Methods: To elucidate the causality of microbiota and vitamin D, we used linkage disequilibrium score (LDSC) regression and two-sample Mendelian randomization (MR) methods with largest genome-wide association study (GWAS) summary statistics to identify specific taxa that are linked to serum 25-hydroxyvitamin D (25(OH)D).Results: We found that Ruminiclostridium9 was significantly genetically correlated with 25(OH)D at nominal significance (rg = 0.43, P = 0.04). Applying the inverse variance weighted (IVW) method, we identified that doubling the genetic liability of abundance of Erysipelotrichia, Erysipelotrichaceae and Erysipelotrichales reduced the concentration of 25(OH)D by 0.06 standard deviation (SD) (βIVW = -0.06, s.e. = 0.01, P = 1.48 × 10-6, PFDR = 1.93 × 10-4) and, in turn, one SD increment in genetically determined serum 25(OH)D caused a 0.16 SD decrease in the relative abundance of Phascolarctobacterium (βIVW = -0.16, s.e. = 0.04, P = 2.48 × 10-4, PFDR = 0.02) after removing pleiotropic instruments and outliers. Moreover, four MR methods were also used to evaluate causality, the results of which supported these findings. Leave-one-out analyses showed that the results were robust with regard to alterations in the single nucleotide polymorphisms (SNPs) we selected.Conclusions: In conclusion, our results support the hypothesis that the gut microbiota mediates the absorption of serum vitamin D supplementation and interacts with it closely. These microbiota are potential therapeutic targets for promoting serum vitamin D homeostasis. [ABSTRACT FROM AUTHOR]

Background/Objectives:Middle Eastern female immigrants are at an increased risk of vitamin D deficiency and their response to prescribed vitamin D dosages may not be adequate and affected by other factors. The objectives were to determine vitamin D deficiency and its determinants in Middle Eastern women living in Auckland, New Zealand (Part-I), and to determine serum 25-hydroxyvitamin D (serum-25(OH)D) response to two prescribed vitamin D dosages (Part-II) in this population.Participants/Methods:Women aged ⩾20 (n=43) participated in a cross-sectional pilot study during winter (Part-I). In Part-II, women aged 20-50 years (n=62) participated in a randomised, double-blind placebo-controlled trial consuming monthly either 50 000, 100 000 IU vitamin D3 or placebo for 6 months (winter to summer).Results:All women in Part-I and 60% women in Part-II had serum-25(OH)D<50 nmol/l. Serum-25(OH)D was higher in prescribed vitamin D users than nonusers (P=0.001) and in Iranians than Arab women (P=0.001; Part-I). Mean (s.d.) serum-25(OH)D increased in all groups (time effect, P<0.001) and differed between groups (time × dosage interaction, P<0.001; 50 000 IU: from 44.0±16.0 to 70.0±15.0 nmol/l; 100 000 IU: 48.0±11.0 to 82.0±17.0 nmol/l; placebo: 45.0±18.0 to 54.0±18.0 nmol/l). Only 32% and 67% achieved serum-25(OH)D⩾75 nmol/l with 50 000 and 100 000 IU/month, respectively. Predictors of 6-month change in serum-25(OH)D were dose (B-coefficient±s.e.; 14.1±2.4, P<0.001), baseline serum-25(OH)D (−0.6±0.1, P<0.001) and body fat percentage (−0.7±0.3, P=0.01).Conclusions:Vitamin D deficiency/insufficiency is highly prevalent in this population. Monthly 100 000 IU vitamin D for 6 months is more effective than 50 000 IU in achieving serum-25(OH)D ⩾75 nmol/l; however, a third of women still did not achieve these levels. [ABSTRACT FROM AUTHOR]

Background/objectives: Maternal vitamin D deficiency during pregnancy may influence offspring kidney health. We aimed to examine the associations of 25-hydroxyvitamin D (25(OH)D) blood levels during fetal life with kidney outcomes at school age.Subjects/methods: This study was embedded in a population-based prospective cohort study among 4212 mother-child pairs. We measured maternal second trimester (18-25 weeks) and fetal cord blood (at birth) 25(OH)D levels. At a median age of 6.0 years, we measured children's combined kidney volume, glomerular filtration rate (eGFR) from creatinine and cystatin C serum levels, and microalbuminuria from albumin and creatinine urine levels.Results: Of all mothers, 21.9% had severely deficient levels (25(OH)D <25.0 nmol/l), 25.7% had deficient levels (25.0-49.9 nmol/l), 25% had sufficient levels (50.0-74.9 nmol/l) and 27.4% had optimal levels (⩾75.0 nmol/l). Maternal 25(OH)D levels were not consistently associated with childhood combined kidney volume. Higher maternal 25(OH)D levels were associated with lower childhood eGFR (difference -0.94 ml/min per 1.73 m(2) (95% confidence interval, -1.73; -0.15) per 1 standard deviation (s.d.) increase in 25(OH)D). Maternal 25(OH)D levels were not associated with microalbuminuria. Cord blood 25(OH)D levels were not associated with childhood kidney outcomes. The associations of maternal 25(OH)D levels with childhood eGFR were partly explained by childhood vitamin D status.Conclusions: Our findings suggest that maternal 25(OH)D levels during pregnancy may influence childhood kidney outcomes. These results should be considered hypothesis generating. Further studies are needed to replicate the observations, to examine the underlying mechanisms and to identify the long-term clinical consequences. [ABSTRACT FROM AUTHOR]

Background/objectives: The association between active lifestyle components and vitamin D status in adolescents remains relatively unexplored. We aimed to investigate independent and joint associations of moderate-to-vigorous physical activity (MVPA) and screen time with serum 25-hydroxyvitamin D [25(OH)D] concentrations in adolescents.Methods: This multicenter cross-sectional study involved 1152 Brazilian adolescents (age 12-17 years). Serum 25(OH)D was measured in a single laboratory and categorized as ≤20, 21-29, or ≥30 ng/mL. Demographic and lifestyle characteristics were assessed by self-reports. Ordered logistic regression was used to investigate potential associations of being physically active (MVPA ≥ 300 min/week) and excessive screen time (>2 h/day) with serum 25(OH)D concentrations.Results: The prevalence of higher serum 25(OH)D concentrations (≥30 ng/mL) was 36.4%. In adjusted models, being physically active was associated with higher serum 25(OH)D concentrations only in boys [proportional odds ratio (POR) = 2.04, 95% CI 1.42-2.93], while excessive screen time was not associated with serum 25(OH)D. Adolescents who were physically active and limited their screen time had higher odds of a higher serum 25(OH)D concentration, but the association was significant only for boys (POR = 2.11, 95% CI 1.19-3.74).Conclusions: MVPA may play an important role in increasing serum 25(OH)D concentrations in adolescence, especially for boys, regardless of screen time. [ABSTRACT FROM AUTHOR]

Background/Objectives:The increase of bone disease in adult cystic fibrosis (CF) patients is partly attributed to inadequate serum concentrations of 25-OH cholecalciferol (25 (OH) D) blamed on fat malabsorption. Based on physiological, clinical and biochemical observations this pathogenesis is debatable. The objective was to ascertain the relative importance of different 25 (OH) D sources.Subjects/Methods:Over 4 consecutive years, 474 annual 25 (OH) D serum concentrations from 141 CF patients of all ages were compared with values of healthy peers and weighed against annual ultraviolet B (UVB) exposure.Results:Ranked per month, 25 (OH) D concentrations depicted a curve strikingly parallel to the amount of UVB exposure in the preceding months. A significant difference exists between 25 (OH) D concentrations in the 'Months with high UVB exposure' (May-October) and the 'Months with low UVB exposure' (November-April) but not with healthy controls in the same period.Conclusions:25 (OH) D concentrations clearly respond to the amount of sunshine in preceding months. They are not clearly influenced by daily oral supplements of 800 IU of cholecalciferol. Sun exposure should be encouraged, and the recommended dosage of oral supplements increased. [ABSTRACT FROM AUTHOR]

Background/objectives: To evaluate serum 25(OH)D concentrations and determine a cutoff point for cardiometabolic risk in children.Subject/methods: This is a cross-sectional study with a representative sample of 378 8-9-year-old children from all urban schools in the city of Viçosa, MG, Brazil. Sociodemographic data and information on lifestyle, and food consumption were collected. Biochemical evaluation included glucose, triglycerides, leptin, calcidiol [25(OH)D], and parathormone. Body composition was assessed by dual energy X-ray absorptiometry. Cardiometabolic risk was considered when nontraditional risk markers were detected, including triglyceride × glycemia index (TyG index), hyperleptinemia, and hypertriglyceridemic waist phenotype (HWP). The receiver operating characteristic curve (ROC) was used to define the cutoff point for serum 25(OH)D to predict cardiometabolic risk.Results: 25(OH)D showed better predictive capacity for grouping of cardiometabolic risk markers than for either single or paired markers. The area under the curve for grouping of risk markers was 0.636 (95% CI: 0.585, 0.685, P < 0.001). The cutoff point to predict cardiometabolic risk was defined as 32.0 ng/mL.Conclusion: 25(OH)D presented good predictive capacity for cardiometabolic risk and 25(OH)D concentration higher than 32 ng/mL was associated with a 49% reduction of cardiometabolic risk prevalence in prepubertal Brazilian children. [ABSTRACT FROM AUTHOR]

Inadequate vitamin D nutritional status is prevalent worldwide and has been associated with autoimmune disorders, heart disease, deadly cancers, insulin resistance, inflammation, neurological disorders, adverse outcomes in pregnancy, and increased risk for mortality. Expert recommendations for vitamin D intake differ between governmental agencies and practice guidelines from medical societies due to differences in the definition of vitamin D deficiency, insufficiency and sufficiency based on serum 25-hydroxyvitamin D [25(OH)D] concentrations. In addition, separate health promotion bodies also provide targeted recommendations for the prevention of specific disorders such as reducing risk for developing some cancers and autoimmune diseases. We review and provide perspectives regarding various recommendations from the Institute of Medicine (IOM, United States) and Health Canada, the European Food Safety Authority (EFSA), the Scientific Advisory Committee on Nutrition (SACN; United Kingdom), the World Health Organization, the Endocrine Society and other expert groups by life stage as a guide intended for clinician use. [ABSTRACT FROM AUTHOR]

Studies have indicated that 25-hydroxyvitamin D (25(OH)D) level in obese is lower than normal weight subjects; however, results of studies that investigated relationship between 25(OH)D and fat mass are inconsistent. In addition, several randomized clinical trials (RCTs) have studied the influence of cholecalciferol supplement on percentage fat mass (PFM) but their results are conflicting. The objectives were to investigate the association between vitamin D3 and PFM pooling together observational studies and RCTs. PubMed/MEDLINE, Cochrane, and Scopus were comprehensively searched from inception to September 2016. The Fisher's Z (SE) of correlation coefficient and mean (SD) of changes in PFM from baseline were used to perform meta-analysis in observational studies and RCTs, respectively. To determine potential source of heterogeneity, subgroup and meta-regression analyses were conducted. Pooling correlation coefficients showed an inverse association between PFM (Fisher's Z: - 0.24, 95% CI: - 0.30 to -0 .18) and FM (Fisher's Z: - 0.32, 95% CI: - 0.43 to - 0.22) and 25(OH)D. Subgroup analysis revealed continent but not gender influence on the effect size. Meta-regression analysis indicated that age, latitude, and longitude are not sources of heterogeneity. Combining trials showed vitamin D3 supplementation had a mild but insignificant effect on PFM (- 0.31%, 95% CI: - 1.07 to 0.44). Subgroup analyses indicated that type of cholecalciferol and treatment regimens explain source of heterogeneity. Age, baseline body mass index, dose of cholecalciferol, length of study, female (%), and baseline 25(OH)D are not source of heterogeneity. In conclusion, our results state that 25(OH)D level is inversely correlated with PFM but cholecalciferol supplementation had no effect on PFM. [ABSTRACT FROM AUTHOR]