Vitamin D3 dose requirement to raise 25-hydroxyvitamin D to desirable levels in adolescents: results from a randomized controlled trial

Oral vitamin D supplementation and body weight in children and adolescents: a systematic review and meta-analysis of randomized controlled trials

This study was designed to ascertain whether oral vitamin D supplementation (oral supplementation and fortified foods) is associated with changes in body weight measures in children and adolescents, using a systematic review and meta-analysis of randomized controlled trials (RCTs). PubMed, Scopus, Cochrane, and Web of Science databases were searched from inception to October 28, 2022. The mean difference and corresponding 95% confidence interval (CI) of interested outcomes were pooled using a random-effects model. Twenty-one RCTs were included in the meta-analysis, and the results showed a significant decrease in body mass index (BMI) following vitamin D supplementation in children and adolescents (n = 9 studies, 1029 participants; weighted mean difference: - 0.43 kg/m², 95% CI: - 0.79, - 0.08; P = 0.02; I² = 58.5%). Overall, oral vitamin D supplementation had no significant effect on body weight and other anthropometric indices, including fat mass, lean mass, waist circumference, BMI Z-score, and height. Although results of body weight changed to significant after sensitivity analysis (WMD = 0.39 kg, 95% CI = 0.01, 0.78; P = 0.04; I² = 0%, P-heterogeneity = 0.71), we also found significant weight gain in healthy pediatric population, and when the dose of vitamin D supplementation was up to 600 IU/day, the certainty of evidence was very low for weight, moderate for height and BMI, and low for the remaining outcomes.

CONCLUSION

Our results suggest that vitamin D supplementation may lead to a statistically significant weight gain in children and adolescents, while BMI was reduced. Although no significant change was observed in height, it seems vitamin D supplementation may elicit these changes by increasing skeletal growth; however, this remains to be verified. Further high-quality RCTs, with longer duration and larger sample sizes, are needed to yield more certain evidence in this regard.

WHAT IS KNOWN

• Available evidence indicates an inverse association between body weight/fat mass and vitamin D status in children and adolescents; however, findings regarding the effect of vitamin D supplementation on anthropometric measurements in children are controversial.

WHAT IS NEW

• Our results showed a significant decrease in BMI following vitamin D supplementation in children. • A significant weight gain also was observed after sensitivity analysis, and in healthy pediatric population, and when the dose of vitamin D supplementation was up to 600 IU/day.

How Much Does Serum 25(OH)D Improve by Vitamin D Supplement and Fortified Food in Children? A Systematic Review and Meta-Analysis

OBJECTIVES

This study was conducted to respond certain important questions regarding the efficacy of vitamin D fortification and supplementation in children using a meta-analytical approach.

METHODS

MEDLINE, PubMed, Embase, Cochrane Library, and Google Scholar were searched, and 2341 studies were found in a preliminary search. After screening of titles and abstracts, 31 studies were selected.

RESULTS

Significant raises in circulating 25-hydroxy vitamin D (25(OH)D) concentrations were observed in both groups that took vitamin D supplement (mean difference [MD] 28.7, 95% confidence interval [CI] 22.5-34.9) and vitamin D-fortified foods (MD 20.29, 95% CI 13.3-27.2). The meta-regression revealed a significant association between age of participants (B -1.4, 95% CI -2.8, -0.02, P = 0.047) and dose of vitamin D (B 0.007, 95% CI 0.003, 0.01, P < 0.001), with the effect on serum 25(OH)D concentrations. The analysis showed that serum 25(OH)D concentration increases by 0.7 nmol/L for every 100 IU of vitamin D intake after adjustment for age, baseline serum 25(OH)D and latitude which is far less than the reported amount in adults.

CONCLUSIONS

Altogether, these findings indicate that in a mass vitamin D fortification program, circulating 25(OH)D concentration response in children may be lower in children than in adults and vitamin D supplementation may still be needed in this subpopulation.

Three monthly doses of 150,000 IU of oral cholecalciferol correct vitamin D deficiency in adolescents: A pragmatic study

OBJECTIVES

To assess the efficacy of an oral high-dose cholecalciferol regimen in correcting vitamin D deficiency (VDD) in adolescents and to explore potential predictive factors on the response to treatment.

METHODS

This is a retrospective chart review conducted in the Adolescent Outpatient Clinic, Geneva University Hospitals, Switzerland. One hundred-three otherwise healthy vitamin D deficient [serum 25-hydroxyvitamin D, 25(OH)D, level <50 nmol/L] adolescents (mean age 16.6) attending the clinic between 1 January 2016 and 31 December 2018 received 150,000 IU of oral cholecalciferol every month for 3 months (cumulative dose of 450,000 IU). We measured the change in serum 25(OH)D levels pre- and post-treatment and the achievement of serum 25(OH)D level post-treatment ≥75 nmol/L.

RESULTS

The mean serum 25(OH)D level increased by 320%, from 26 nmol/L at baseline to 83 nmol/L at the end of the study (P < .001). The rise was significantly higher for patients initially tested in the winter/spring (mean 65 nmol/L) compared with those initially tested in the summer/autumn (mean 48 nmol/L) (P < .003). No clear relationship was found between the response to treatment and the vitamin D status at baseline. The effect of age, gender, origin and body mass index was not statistically significant.

CONCLUSIONS

The present intermittent high-dose regimen is effective in treating VDD in healthy adolescents without significant variations in response between different subgroups.

Daily vitamin D3 in overweight and obese children and adolescents: a randomized controlled trial

PURPOSE

To assess the efficacy of different doses of vitamin D₃ on serum 25-hydroxyvitamin D (25(OH)D), intact parathyroid hormone(iPTH), calcium, phosphorus, and alkaline phosphatase concentrations in overweight and obese school-children.

METHODS

A total of 378 children and adolescents, 6-13 years of age, with age- and sex-specific body mass index(BMI) Z-score ≥ 1(according to the World Health Organization criteria) were allocated to receive 600, 1000, and 2000 IU vitamin D₃/days. 25(OH)D, iPTH, calcium, phosphorus, and alkaline phosphatase concentrations were measured at baseline, 6, and 12 months. In this intention-to-treat analysis, we fitted a linear mixed effect model involving a random effect of participants within treatment groups and fixed effects of dose, time, and their interactions.

RESULTS

Mean(SD) of age and BMI Z-score were 9.3 (1.7) years and 2.55 (0.73), respectively. The median (IQR) for 25(OH)D was 11.5 (8.9), 11.7 (10.5), 12.2 (10.2) ng/mL (28.75, 29.25, and 30.50 nmol/L) at baseline and 23.1 (8.0), 25.6 (8.3), 28.6 (10.4) ng/mL (57.75, 64.00, and 71.50 nmol/L) at the end of 12 months in 600, 1000, and 2000 IU, respectively (p values for dose, time, and the interaction being < 0.0001, < 0.0001,and 0.082, respectively). Prevalence of vitamin D deficiency (< 20 ng/mL) was 80.2, 77.5, and 75.5% in 600, 1000, and 2000 IU groups at baseline, respectively, which decreased to 34, 18.4, and 7.5%, respectively, at 12 months. Patterns of iPTH, calcium, phosphorus, and alkaline phosphatase response over time did not differ significantly among groups (p values = 0.452, 0.670, 0.377, 0.895, respectively).

CONCLUSIONS

Increases in 25(OH)D concentration were found with supplementation of 1000 and 2000 IU, compared with 600 IU/days, whereas there was no evidence of iPTH suppression or change in serum calcium, phosphorus, and alkaline phosphatase among children with excess weight.

Safety and effectiveness of stoss therapy in children with vitamin D deficiency

AIM

Paediatric vitamin D (25-hydroxyvitamin D (25OHD)) deficiency can lead to nutritional rickets and extra-skeletal complications. Compliance with daily therapy can be difficult, making high-dose, short-term vitamin D (stoss) therapy attractive to correct vitamin D deficiency. We compared the effectiveness and safety of standard versus stoss therapy in treating childhood 25OHD deficiency.

METHODS

Children aged 2-16 years with 25OHD <50 nmol/L were randomised to either standard (5000 IU daily for 80 days) or stoss (100 000 IU weekly for 4 weeks) cholecalciferol. Participants underwent an evaluation of effectiveness and safety. The 25OHD level, random spot calcium: creatinine ratio (Ca:Cr) and compliance were measured at 12 weeks.

RESULTS

A total of 151 children were enrolled in the study (68 standard and 83 stoss), median age 9 years (inter-quartile range (IQR): 6-12 years). Baseline 25OHD levels were 26 nmol/L (IQR: 19-35 nmol/L) and 32 nmol/L (IQR: 24-39 nmol/L) in the standard and stoss groups, respectively. At 12 weeks, the median 25OHD level was significantly greater in the standard versus stoss group (81 vs. 67 nmol/L; P = 0.005); however, >80% of participants in both groups achieved sufficiency (25OHD > 50 nmol/L) and had normal urinary Ca:Cr, with no significant difference seen between groups. Compliance was similar in the two groups.

CONCLUSIONS

Compared to stoss, standard therapy achieved higher 25OHD levels at 12 weeks; however, in both groups, there was a similar proportion of participants who achieved 25OHD sufficiency, with no evidence of toxicity. Unlike other studies, simplifying the treatment regimen did not improve compliance. These results support stoss therapy as an effective and safe alternative therapy for the treatment of paediatric vitamin D deficiency.

Effects of different vitamin D supplementation strategies in reversing metabolic syndrome and its component risk factors in adolescents

There is little evidence on the efficacy of various vitamin D supplementation strategies in reversing metabolic syndrome (MetS) in adolescents. The present study aims to fill this gap. A total of 535 (243/292) out of 650 apparently healthy Saudi adolescents were randomly selected from the Vitamin D School Project database which has baseline and post-intervention information of more than 1000 Saudi adolescents 12-18 years old attending 34 schools in Riyadh, Saudi Arabia from Nov 2014-May 2015. Allocation of intervention was done in 3 groups using cluster randomization: vitamin D tablet, 1000IU/day (N = 180; 69 boys, 111 girls); vitamin D fortified milk consumption, 200 ml/day, 40IU/100 ml (N = 189; 93 boys, 96 girls) and control (educational awareness) (N = 166; 81 boys, 85 girls). All groups were given educational awareness on how to increase vitamin D levels. All groups were matched for BMI and analysis adjusted for age. Post-intervention and using intent-to-treat approach, within-group analysis revealed a statistically significant increase in 25(OH)D levels in all groups, and a clinically significant increase in favor of the tablet group (between-group) [10.7 nmol/l (34.7%) versus 6.3 nmol/l (19.8%) in milk and 2.1 nmol/l (7.0%) in control; p < 0.001], adjusted for age and BMI-matched. Between group analysis also revealed a clinically significant decrease in triglycerides (p = 0.05), glucose (p < 0.001) and systolic blood pressure (p = 0.005) as well as a clinically significant increase in HDL-cholesterol (p = 0.004) over time, all in favor of the tablet group. Within-group comparison showed a significant decrease in the incidence of MetS in the tablet group (9.4% versus 4.4%; p < 0.05) only. In conclusion, oral vitamin D supplementation is superior to vitamin D fortified milk in improving vitamin D status. Reduction in the incidence of MetS in the Arab adolescent population secondary to vitamin D correction may be dose-dependent.

Reference range of random urinary calcium creatinine ratio in North Indian children and adolescents

PURPOSE

Urinary calcium creatinine ratio (UCaCrR) is a reliable indicator for monitoring hypercalciuria following vitamin D supplementation. However, the reference range varies from region to region. Previous studies did not take vitamin D and parathyroid hormone status into account while evaluating UCaCrR. Hence, we undertook this study to establish the 95th percentile of UCaCrR as an indicator of hypercalciuria in North Indian children and adolescents.

METHODS

Four hundred seventy-three participants (boys 62.2%, girls 37.8%) with adequate dietary calcium intake, normal serum levels of 25-hydroxy-vitamin D (&gt;20 ng/mL), and without secondary hyperparathyroidism following supplementation were selected for evaluation of UCaCrR.

RESULTS

The mean age and body mass index of subjects were 11.2±2.6 years and 18.0±3.6 kg/m2, respectively. The 95th percentile of UCaCrR in the study population was 0.126. The mean, median, and 95th percentile of UCaCrR was significantly higher in prepubertal children (age ≤10 years) (0.0586±0.0374, median=0.0548, 95th percentile=0.136) compared to those &gt;10 years old (0.0503±0.0363, median=0.0407, 95th percentile=0.123, P=0.02). No significant difference in UCaCrR was observed between genders and different weight categories.

CONCLUSION

UCaCrR of 0.13 defines the cutoff value for hypercalciuria in North Indian children and adolescents with adequate dietary intake of calcium and sufficient serum vitamin D levels.

Impact of three different daily doses of vitamin D3supplementation in healthy schoolchildren and adolescents from North India: a single-blind prospective randomised clinical trial

In India, there is a lack of information about the adequate daily dose of vitamin D3supplementation in school children. Hence, we undertook this study to evaluate the adequacy and efficacy of different doses of vitamin D3in schoolchildren. A total of 1008 vitamin D-deficient (VDD) children, aged 6–16 years with serum 25-hydroxyvitamin D (25(OH)D) levels <50nmol/l, were cluster randomised into three groups (A-344, B-341 and C-232) for supplementation (600, 1000 and 2000 IU daily) of vitamin D3under supervision for 6 months. Of the 1008 subjects who completed the study, 938 (93 %) were compliant. Baseline and post-supplementation fasting blood and urine samples were evaluated for Ca, phosphates, alkaline phosphatase, 25(OH)D and parathormone and urine Ca:creatinine ratio. The mean age of the subjects was 11·7 (sd2·4) years, and the overall mean baseline serum 25(OH)D level was 24·3 (SD9·5)nmol/l. Post-supplementation rise in serum 25(OH)D in compliant group was maximum with 2000 IU (70·0 (SD30·0)nmol/l), followed by 1000 IU (46·8 (SD22·5)nmol/l) and 600 IU (36·5 (SD18·5)nmol/l), and serum 25(OH)D levels of ≥50nmol/l were achieved in 71·5, 81·8 and 92·9 % by groups A, B and C, respectively. Secondary hyperparathyroidism decreased from 31·7 to 8·4 % post-supplementation. Two participants developed hypercalciuria, but none developed hypercalcaemia. Children with VDD benefit maximum with the daily supplementation of 2000 IU of vitamin D3. Whether recommendations of 400 IU/d by Indian Council of Medical Research or 600 IU by Indian Academy of Pediatrics or Institute of Medicine would suffice to achieve vitamin D sufficiency in children with VDD remains debatable.

Effects of Vitamin D Supplementation on Haematological Values and Muscle Recovery in Elite Male Traditional Rowers

INTRODUCTION

Deficient levels of 25-hydroxyvitamin D (25(OH)D) (<30 ng/mL) may compromise health and athletic performance. Supplementation with oral vitamin D can favor the state of iron metabolism, and testosterone and cortisol as an indicator of muscle recovery of the athlete with a deficiency. The main aim of this study was to evaluate the influence of eight weeks of supplementation with 3000 IU/day of vitamin D on the hematological and iron metabolism profile, as well as on the analytical values of testosterone and cortisol on elite male traditional rowers. The secondary aim was to examine if serum 25(OH)D is a predictor of testosterone and cortisol levels.

MATERIAL AND METHODS

Thirty-six elite male rowers (27 ± 6 years) were assigned to one of the two groups randomly: 1) Control group (CG, n = 18, height: 181.05 ± 3.39 cm and body mass: 77.02 ± 7.55 kg), 2) Group treated with 3,000 IU of vitamin D3/day (VD3G, s = 18, height: 179.70 ± 9.07 cm and body mass: 76.19 ± 10.07 kg). The rowers were subjected to blood tests at the beginning of the study (T1) and after eight weeks of treatment (T2), for the analysis of hematological and hormonal values. Repeated-measures ANOVA with group factor (GC and GVD3) were used to examine if the interaction of the different values was the same or different between the groups throughout the study (time × group) after vitamin D3 treatment. To analyze if 25(OH)D was a good predictor of testosterone, cortisol, and testosterone/cortisol ratio a stepwise regression model was performed.

RESULTS

Statistically significant and different increases were observed in the group-by-time interaction of 25(OH)D in VD3G in respect to CG during the study (p < 0.001; VD3G (T1: 26.24 ± 8.18 ng/mL vs. T2: 48.12 ± 10.88 ng/mL) vs CG (T1: 30.76 ± 6.95 ng/mL vs. T2: 35.14 ± 7.96 ng/mL). Likewise, significant differences between groups were observed throughout the study in the group-by-time interaction and changes of hemoglobin (GC: -2.89 ± 2.29% vs. VD3G: 0.71 ± 1.91%; p = 0.009), hematocrit (CG: -1.57 ± 2.49% vs. VD3G: 1.16 ± 1.81%; p = 0.019) and transferrin (CG: 0.67 ± 4.88% vs. VD3G: 6.51 ± 4.36%; p = 0.007). However, no differences between groups were observed in the group-by-time interaction of the hormonal parameters (p > 0.05). Regression multivariate analysis showed that cortisol and testosterone levels were associated with 25(OH)D levels (p < 0.05).

CONCLUSION

Oral supplementation with 3000 IU/day of vitamin D3 during eight weeks showed to be sufficient to prevent a decline in hematological levels of hemoglobin and hematocrit, and improve transferrin of 25(OH)D levels. However, although it was not sufficient to enhance muscle recovery observed by testosterone and cortisol responses, it was observed that serum 25(OH)D levels could be a predictor of anabolic and catabolic hormones.

Vitamin D insufficiency: Definition, diagnosis and management

Severe vitamin D deficiency can be defined as the dose of vitamin D or serum 25OHD concentrations needed to prevent nutritional rickets or osteomalacia. There is large international consensus that these diseases can be prevented by 400 IU of vitamin D/d and 25OHD above 30 nmol/l (12 ng/ml). Vitamin D deficiency can also accelerate the risk of fractures and probably also of falls in elderly subjects but there is no consensus on the required daily doses or minimal 25OHD threshold for these endpoints. The majority of experts consider 800 IU/d and serum 25OHD above 50 nmol/l (20 ng/ml) as sufficient, with a minority opinion aiming for 75 nmol/l or even higher. For other extra-skeletal endpoints, no hard evidence is available to define whether or not this is causally related to vitamin D status. Therefore, for these endpoints no minimal dosage or 25OHD threshold can be defined.

Effect of Vitamin D Supplementation, Food Fortification, or Bolus Injection on Vitamin D Status in Children Aged 2-18 Years: A Meta-Analysis

Meta-analyses on the effect of vitamin D intake on status in children are lacking, especially those focused on vitamin D-fortified foods. The objective of this meta-analysis was to investigate the effect of vitamin D interventions (fortified foods, supplements, bolus injections) on vitamin D status in children 2-18 y of age. Following PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, literature searches were conducted up to December 2016. Randomized placebo-controlled vitamin D interventions in healthy children aged 2-18 y were included. A random-effects model was used with I2 assessing heterogeneity. We included 26 trials (5403 children) with interventions (n = 9 fortified foods, n = 15 supplements, n = 2 bolus injections) from 100-4000 IU vitamin D/d over 4 wk to 2 y. The serum 25-hydroxyvitamin D [25(OH)D] weighted mean difference for all 26 trials (23.5 nmol/L; 95% CI: 20.7, 26.3 nmol/L; I2 = 99.9%) resulted in a mean increase of 1.0 nmol/L (95% CI: 0.3, 1.7 nmol/L) for each increase of 100 IU vitamin D/d (per 1 µg/d : 0.4 nmol/L; 95% CI: 0.1, 0.7 nmol/L). The response per 100 IU vitamin D/d was greater in trials with a mean baseline serum 25(OH)D <30 nmol/L, with the use of fortified foods and with baseline vitamin D intakes <100 IU/d. In conclusion, the serum 25(OH)D response to vitamin D intake differs on the basis of baseline status, intakes, and delivery mode, but not age, sex, or latitude.

Vitamin D in pediatric age: consensus of the Italian Pediatric Society and the Italian Society of Preventive and Social Pediatrics, jointly with the Italian Federation of Pediatricians

Vitamin D plays a pivotal role in the regulation of calcium-phosphorus metabolism, particularly during pediatric age when nutritional rickets and impaired bone mass acquisition may occur.Besides its historical skeletal functions, in the last years it has been demonstrated that vitamin D directly or indirectly regulates up to 1250 genes, playing so-called extraskeletal actions. Indeed, recent data suggest a possible role of vitamin D in the pathogenesis of several pathological conditions, including infectious, allergic and autoimmune diseases. Thus, vitamin D deficiency may affect not only musculoskeletal health but also a potentially wide range of acute and chronic conditions. At present, the prevalence of vitamin D deficiency is high in Italian children and adolescents, and national recommendations on vitamin D supplementation during pediatric age are lacking. An expert panel of the Italian Society of Preventive and Social Pediatrics reviewed available literature focusing on randomized controlled trials of vitamin D supplementation to provide a practical approach to vitamin D supplementation for infants, children and adolescents.

Vitamin D in adolescents: Are current recommendations enough?

Vitamin D is essential for bone development during adolescence and low vitamin D status during this critical period of growth may impact bone mineralization, potentially reducing peak bone mass and consequently increasing the risk of osteoporosis in adulthood. Therefore, the high prevalence of vitamin D inadequacy and deficiency in adolescent populations is of great concern. However, there is currently a lack of consensus on the 25-hydroxyvitamin D [25(OH)D] concentration, the widely accepted biomarker of vitamin D status, that defines adequacy, and the vitamin D intake requirements to maintain various 25(OH)D thresholds are not well established. While the current intake recommendations of 10-15μg/day may be sufficient to prevent vitamin D deficiency (25(OH)D<25-30nmol/l), greater intakes may be needed to achieve the higher threshold levels proposed to represent adequacy (25(OH)D>50nmol/l). This review will address these concerns and consider if the current dietary recommendations for vitamin D in adolescents are sufficient.

Vitamin D supplementation for preventing infections in children under five years of age

BACKGROUND

Vitamin D is a micronutrient important for bone growth and immune function. Deficiency can lead to rickets and has been linked to various infections, including respiratory infections. The evidence on the effects of supplementation on infections in children has not been assessed systematically.

OBJECTIVES

To evaluate the role of vitamin D supplementation in preventing pneumonia, tuberculosis (TB), diarrhoea, and malaria in children under five years of age. This includes high-, middle-, and low-income countries.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register, the Cochrane Central Register of Controlled Trials (CENTRAL), the Cochrane Library, MEDLINE, EMBASE, LILACS, the WHO International Clinical Trials Registry Platform (ICTRP; http://www.who.int/ictrp/en/) , ClinicalTrials.gov and the ISRCTN registry (http://www.isrctn.com/) up to 16 June 2016.

SELECTION CRITERIA

We included randomized controlled trials (RCTs) that evaluated preventive supplementation of vitamin D (versus placebo or no intervention) in children under five years of age.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the titles and abstracts, extracted the data, and assessed the risk of bias of included trials.

MAIN RESULTS

Four trials met the inclusion criteria, with a total of 3198 children under five years of age, and were conducted in Afghanistan, Spain, and the USA. Prevalence of vitamin D deficiency varied widely in these populations (range: 73.1% in Afghanistan, 10 to 12% in USA, and 6.2% in Spain). The included trials evaluated mortality (two trials), pneumonia incidence (two trials), diarrhoea incidence (two trials), hospitalization (two trials), and mean serum vitamin D concentrations (four trials).We do not know whether vitamin D supplementation impacts on all-cause mortality because this outcome was underpowered due to few events (risk ratio (RR) 1.43, 95% confidence interval (CI) 0.54 to 3.74; one trial, 3046 participants, low quality evidence).For pneumonia, episodes of 'radiologically confirmed' first or only episode of pneumonia were little different in the supplemented and unsupplemented group (Rate Ratio: 1.06, 95% confidence interval (CI) 0.89 to 1.26; two trials, 3134 participants, moderate quality evidence), and similarly for children with confirmed or unconfirmed pneumonia (RR 0.95, 95% CI 0.87 to 1.04; one trial, 3046 participants). In these two trials there were no obvious differences between supplemented and unsupplemented children regarding episodes of diarrhoea.In the single large trial from Afghanistan, the trial authors reported that vitamin D supplementation was associated with an increase in repeat episodes of pneumonia confirmed by chest radiograph (RR 1.69, 95% CI 1.28 to 2.21; one trial, 3046 participants), but not reflected in the outcome of confirmed or unconfirmed pneumonia (RR 1.06, 95% CI 1.00 to 1.13; one trial, 3046 participants).For hospital admission measured in one small trial, there was no difference detected (RR 0.86, 95% CI 0.20 to 3.62; one trial, 88 participants; very low quality evidence).The mean serum vitamin D concentrations were higher in supplemented compared to unsupplemented children at the end of supplementation (MD 7.72 ng/mL, 95% CI 0.50 to 14.93; four trials, 266 participants, low quality evidence). These results were driven primarily by two smaller trials with large magnitudes of effect. In the other two bigger trials, serum vitamin D concentrations were elevated in the intervention group for most of the trial duration but not at the end of supplementation. This may be due to time elapsed at measurement from the last dose, incomplete compliance, or increased need of vitamin D with infant age.We did not find any trial that reported on the incidence of TB, malaria or febrile illness, duration of pneumonia, duration of diarrhoea, severity of infection, and cause-specific mortality (due to TB, diarrhoea, or malaria).

AUTHORS' CONCLUSIONS

Evidence from one large trial did not demonstrate benefit of vitamin D supplementation on the incidence of pneumonia or diarrhoea in children under five years. To our knowledge, trials that evaluated supplementation for preventing other infections, including TB and malaria, have not been performed.

Estimation of the dietary requirement for vitamin D in adolescents aged 14-18 y: a dose-response, double-blind, randomized placebo-controlled trial

BACKGROUND

Adolescents are a population group at high risk of low vitamin D status, yet the evidence base for establishing dietary vitamin D requirements remains weak.

OBJECTIVE

The aim was to establish the distribution of vitamin D intakes required to maintain serum 25-hydroxyvitamin D [25(OH)D] concentrations above proposed cutoffs (25, 30, 40, and 50 nmol/L) during winter in white males and females (14-18 y of age) in the United Kingdom (51°N).

DESIGN

In a dose-response trial, 110 adolescents (aged 15.9 ± 1.4 y; 43% males) were randomly assigned to receive 0, 10, or 20 μg vitamin D₃ supplements/d for 20 wk during winter. A nonlinear regression model was fit to total vitamin D intake and postintervention serum 25(OH)D concentrations, and regression-predicted values estimated the vitamin D intakes required to maintain serum 25(OH)D concentrations above specific cutoffs.

RESULTS

Mean ± SD serum 25(OH)D concentrations increased from 49.2 ± 12.0 to 56.6 ± 12.4 nmol/L and from 51.7 ± 13.4 to 63.9 ± 10.6 nmol/L in the 10- and 20-μg/d groups, respectively, and decreased in the placebo group from 46.8 ± 11.4 to 30.7 ± 8.6 nmol/L (all P ≤ 0.001). Vitamin D intakes required to maintain 25(OH)D concentrations >25 and >30 nmol/L in 97.5% of adolescents were estimated to be 10.1 and 13.1 μg/d, respectively, and 6.6 μg/d to maintain 50% of adolescents at concentrations >40 nmol/L. Because the response of 25(OH)D reached a plateau at 46 nmol/L, there is uncertainty in estimating the vitamin D intake required to maintain 25(OH)D concentrations >50 nmol/L in 97.5% of adolescents, but it exceeded 30 μg/d.

CONCLUSION

Vitamin D intakes between 10 and ∼30 μg/d are required by white adolescents during winter to maintain serum 25(OH)D concentrations >25-50 nmol/L, depending on the serum 25(OH)D threshold chosen. This trial was registered at clinicaltrials.gov as NCT02150122 and as International Standard Randomized Controlled Trial Number ISRCTN40736890.

Seasonal Vitamin D Status in Polish Elite Athletes in Relation to Sun Exposure and Oral Supplementation

Vitamin D does not only influence the musculoskeletal health and mineral homeostasis but it also affects cardiovascular, endocrine, nervous, immune and mental functions, thus it is of considerable importance for both physically active people and elite athletes. However, vitamin D deficiency is common worldwide and results from inadequate endogenous skin synthesis (insufficient ultraviolet B exposure) and diet. To improve the vitamin D status elite athletes often travel to lower latitude during winter. The aim of the study was to evaluate the seasonal vitamin D status in Polish elite athletes according to the sun exposure and oral supplementation. Serum concentration of 25-hydroxyvitamin D (25(OH)D) was measured in the years 2010–2014 in 409 elite athletes, who were divided into the following groups: OUTD—outdoor sports, represented by track and field athletes, who trained in Poland; IND—weightlifters, handball and volleyball players who trained indoors in Poland; SUN—track and field athletes who trained during Polish winter in lower latitude with high sunshine exposure; SUPL—track and field athletes who trained in Poland, had an inadequate vitamin D status (25(OH)D < 30 ng/ml) and were supplemented orally. Inadequate Vitamin D status was observed in 80% of OUTD and 84% of IND athletes in winter, whereas in summer the values amounted to 42% and 83%, respectively. The athletes exposed to sun in winter had significantly higher vitamin D concentration than OUTD group. Oral supplementation improved vitamin D concentration by 45%, whereas winter sun exposure caused its increase by 85%. Except for a few summer months an inadequate status of vitamin D was found in the majority of Polish elite athletes, with the deficiency level being similar to the one observed in non-athletic population. The most serious deficiency was observed in indoor disciplines. Adequate vitamin D status can be achieved by both increased sun exposure, especially in winter, and oral supplementation. Athletes should therefore routinely assess their vitamin D status and be educated how to approach their sunlight exposure, diet and supplementation.

Treatment of Vitamin D Deficiency in Predominantly Hispanic and Black Adolescents: A Randomized Clinical Trial

OBJECTIVES

To compare 3 different treatment regimens for vitamin D deficiency in minority adolescents and to explore factors that impact treatment efficacy.

STUDY DESIGN

We conducted an 8-week, prospective, open-label, randomized clinical trial in an urban, academic, children's hospital. A total of 183 vitamin D-deficient adolescents, mean 25-hydroxyvitamin D or 25(OH)D 13.7 ± 3.9 ng/mL; mean age 16.6 ± 2.2 years, were randomized into 3 vitamin D3 (cholecalciferol) treatment arms: 50,000 IU/wk; 5000 IU/d; and 1000 IU/d. Serum 25(OH)D and vitamin D binding protein (VDBP) levels were measured pre-and posttreatment; 122 (67%) participants completed posttreatment measures. Complete-case and multiple-imputation, intention-to-treat analyses were performed.

RESULTS

Mean change in 25(OH)D level posttreatment was significantly different among the 3 arms, 24.9 ± 15.1 vs 21.0 ± 15.2 vs 6.2 ± 6.5 ng/mL, for 50,000 IU, 5000 IU, and 1000 IU doses, respectively, P < .001. Both high-dose treatments were effective in increasing the 25(OH)D level out of deficiency range (≥ 20 ng/mL) in more than 80% of participants, and 60% remained deficient after low-dose treatment. Only 72%, 56%, and 2% achieved vitamin D sufficiency (>30 ng/mL) with 50,000 IU, 5000 IU, and 1000 IU doses, respectively, P < .001. Obese participants had substantially less mean change in 25(OH)D level after treatment than normal-weight participants, 13.7 ± 10.7 vs 21.9 ± 16.9 ng/mL, P < .001. Mean baseline VDBP level was almost twice as high in Hispanic compared with black participants (P < .001) and did not alter treatment response or change with treatment.

CONCLUSIONS

Adult-sized adolescents require 8 weeks of high-dose cholecalciferol, at least 5000 IU/d, to correct deficiency. Obese adolescents have poorer response to treatment and may need higher doses than nonobese youth. Hispanic and black adolescents have different VDBP levels but similar treatment responses.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01784029.

Hypovitaminosis D in a Young Lebanese Population: Effect of GC Gene Polymorphisms on Vitamin D and Vitamin D Binding Protein Levels

Bioactive vitamin D is a steroid hormone transported in blood via the vitamin D binding protein (DBP). Our study aimed to investigate the vitamin D status in a young Lebanese population and study the association of hypovitaminosis with levels of DBP. Polymorphisms in the GC gene that encodes DBP were also screened. Blood samples were collected from 179 university students. Vitamin D status and DBP levels were assayed by enzyme-linked immunosorbent assay (ELISA). DNA was extracted from 128 participants, and genotyping of the two GC gene SNPs, rs7041, and rs4588, was carried out by restriction fragment length polymorphism. Forty-seven percent of participants had hypovitaminosis D (<20 ng/ml). A significant positive correlation was observed between vitamin D status and DBP. Genotyping data showed that participants carrying the rs7041 GG and rs4588 AA genotypes had higher concentrations of DBP than those carrying other genotypes. Four allelic versions of the GC gene were observed, one of which, GC*3, was encountered for the first time in this study, and was found to be associated with both normal vitamin D and high DBP levels. Modifying genes such as GC could therefore affect DBP levels, and contribute, along with environmental factors, to the hypovitaminosis D observed in sunny countries.

Serum 25-Hydroxyvitamin D Levels: Variability, Knowledge Gaps, and the Concept of a Desirable Range

Hypovitaminosis D is prevalent worldwide but proportions vary widely between regions, depending on genetic and lifestyle factors, the threshold to define deficiency, and accuracy of 25-hydroxyvitamin D (25OHD) assays used. Latitude, pollution, concealing clothing, sun exposure, gender, dietary habits, and lack of government regulation account for up to 50% in variations in serum 25OHD levels, whereas genetic polymorphisms in the vitamin D pathway account for less than 5%. Organizations/societies have developed guidelines for recommended desirable 25OHD levels and vitamin D doses to reach them, but their applicability across age groups and populations are still debated. This article and the accompanying online Supporting Information highlight sources of variations in circulating 25OHD levels, uncertainties and knowledge gaps, and analytical problems facing 25OHD assays, while keeping efficacy and safety data as the dominant factors when defining a desirable range for 25OHD levels. We propose a desirable range of 20 to 40 ng/mL (50 to 100 nmol/L), provided precise and accurate assays are used. Although slightly lower levels, 15 to 20 ng/mL, may be sufficient for some infants and adults, higher levels, 40 to 60 ng/mL, may still be safe. This desirable range allows physicians to tailor treatment while taking season, lifestyle, vitamin D intake, and other sources of variation into account. We reserve 25OHD measurements for at-risk patients, defined by disease or lifestyle, and the use of 25OHD assays calibrated against the recommended international standards. Most target groups reach desirable target levels by a daily intake of 400 to 600 IU for children and 800 IU for adults. A total daily allowance of vitamin D of up to 1000 IU in the pediatric age groups, and up to 2000 IU in adults, tailored to an individual patient risk profile, is probably safe over long durations. Additional data are needed to validate the proposed range and vitamin D doses, especially in children, pregnant women, and non-white populations.

Large Doses of Vitamin D Fail to Increase 25-Hydroxyvitamin D Levels or to Alter Cardiovascular Risk Factors in Obese Adolescents: A Pilot Study

PURPOSE

Vitamin D deficiency and cardiometabolic risk factors are common in obese adolescents. Observational studies demonstrate an inverse relationship among serum 25-hydroxyvitamin D (25OHD) and obesity, insulin resistance, and inflammatory cytokines. This pilot study explores if vitamin D supplementation could reduce serum concentrations of inflammatory cytokines (interleukin [IL] 6, IL-10, tumor necrosis factor α), adiponectin, lipids, hemoglobin A1C, and high-sensitivity C-reactive protein (hs-CRP). A secondary aim was to determine the associations between baseline serum 25OHD concentrations and body mass index (BMI), hs-CRP, inflammatory cytokines, and lipids.

METHODS

Overweight and obese adolescents enrolled in this 24-week, randomized, double-blind study were given 150,000 IU ergocalciferol or placebo at baseline and 12 weeks. Outcome measurements included serum 25OHD, inflammatory cytokines, adiponectin, hs-CRP, lipids, hemoglobin A1C, and BMI at baseline, 12, and 24 weeks.

RESULTS

Of 40 participants, 31 (78%) completed the study. Mean ± standard error 25OHD levels were similar in vitamin D and placebo groups at baseline (19.6 ± 5.3 vs. 25.8 ± 10.8 ng/mL) and 24 weeks (20.1 ± 3.4 vs. 24.6 ± 8.4 ng/mL). Inflammatory and cardiovascular markers were not significantly different between groups at 24 weeks. Serum 25OHD at baseline was associated with BMI (r = -.44 [95% confidence interval, -.66 to -.15]) but not with other outcome measures.

CONCLUSIONS

Supplementation with vitamin D at 150,000 IU every 3 months failed to increase serum 25OHD or alter inflammatory markers and lipids in overweight and obese youth. Further studies are needed to establish the dose of vitamin D required to increase 25OHD and determine potential effects on metabolic risk factors in obese teens.

Vitamin D supplementation in children with epilepsy and intellectual disability

BACKGROUND

Children with epilepsy and intellectual disability have an increased risk of vitamin D deficiency. In this patient group, it is neither clear which factors are associated with the level of 25-hydroxyvitamin D nor what the therapeutic results are when Dutch guidelines are followed.

METHODS

This retrospective study included 30 patients who, in October 2012, were residents of the children's wards of a tertiary epilepsy center in The Netherlands (Kempenhaeghe). From November 2012 onward they received cholecalciferol supplementation in doses that met or exceeded Dutch guidelines. At baseline, after 6, and 15 months, serum 25-hydroxyvitamin D concentration was measured.

RESULTS

At baseline, the vitamin D status in 11 (36.7%) residents was found to be deficient, in 10 (33.3%) to be insufficient and in 9 (30.0%) sufficient. Supplementation dose, diet, body mass index, intellectual disability, and mobility were significantly associated with baseline 25-hydroxyvitamin D concentrations. The mean 25-hydroxyvitamin D concentration increased significantly from 57.40 ± 22.00 nmol/L at baseline to 89.47 ± 26.77 nmol/L after 15 months (P < 0.001). In spite of supplementation ranging from 400 to 1200 IU/day, 64% of the residents in the deficient category and 30% of those with an insufficient level at baseline failed to attain a sufficient vitamin D status after 15 months.

CONCLUSIONS

Not all residents reached a sufficient vitamin D status after supplementation at least equal to the amount recommended by the Dutch guidelines. In a high-risk population, such as our residents, we advise monitoring 25-hydroxyvitamin D concentrations, adjusting supplementation accordingly and following patients to ensure they reach sufficiency.