Vitamin D deficiency, adiposity, and cardiometabolic risk in urban schoolchildren

Longitudinal associations between vitamin D status and biomarkers of inflammation in a pan-European cohort of children and adolescents

PURPOSE

To investigate longitudinal associations between the vitamin D status and inflammatory markers in children and adolescents.

METHODS

Children from eight European countries from the IDEFICS/I.Family cohort with repeated measurements were included in this study. A linear mixed-effect model was used to model the association of serum 25(OH)D as independent variable and z-scores of inflammatory markers [CRP, cytokines, adipokines, combined inflammation score] as dependent variables, where one level accounts for differences between individuals and the other for changes over age within individuals.

RESULTS

A total of 1,582 children were included in the study. In the adjusted model, 25(OH)D levels were positively associated with adiponectin (β = 0.11 [95% CI 0.07; 0.16]) and negatively with the inflammation score (β = - 0.24 [95% CI - 0.40; - 0.08]) indicating that the adiponectin z-score increased by 0.11 units and the inflammation score decreased by 0.24 units per 12.5 nmol/l increase in 25(OH)D. In children with overweight or obesity, only a positive association between 25(OH)D and IP-10 was observed while in children with normal weight adiponectin was positively and the inflammation score was negatively associated. Associations of vitamin D with adiponectin and the inflammation score were stronger in girls than in boys and a positive association with TNF-α was observed only in girls.

CONCLUSION

Our results suggest that an increase in vitamin D concentrations may help to regulate inflammatory biomarkers. However, it seems to be no benefit of a better vitamin D status in children with overweight/obesity unless their weight is managed to achieve an improved inflammatory marker status.

Severe Vitamin D Deficiency in Youth with Autism Spectrum Disorder During the COVID-19 Pandemic

BACKGROUND

Decrease in sunlight exposure during periods of social distancing during the COVID-19 pandemic increased the risk of severe manifestations of vitamin D deficiency (VDD) in a particular "high-risk" population. Our objective was to highlight the importance of vitamin D screening in youth with autism spectrum disorder (ASD) and restrictive eating.

CASE PRESENTATION

We describe 3 adolescent male patients with ASD who developed severe manifestations of VDD and hypocalcemia in late 2020 during the COVID-19 pandemic. All spent less time outdoors than in prior years because of isolation at home during the pandemic. Presenting symptoms included seizures and atraumatic fractures. All 3 were found to have hypocalcemia and severe VDD. Limited sun exposure because of isolation indoors during the COVID-19 pandemic was a likely contributing factor to the severity of VDD. All 3 were treated with intravenous calcium acutely, followed by oral calcium and vitamin D. Laboratory tests performed post-treatment showed biochemical resolution of hypocalcemia and VDD.

CONCLUSION

These cases highlight the importance of screening "at-risk" youth for VDD. Clinicians should be cognizant that children and adolescents with ASD and restricted eating can have severe manifestations of hypocalcemia and VDD. Decreased sun exposure because of isolating indoors during the COVID-19 pandemic increased their risk for this.

Frequency of Meals Prepared Away from Home and Nutrient Intakes among US Adolescents (NHANES 2011-2018)

Frequency of consuming foods prepared away from home has been associated with lower diet quality among adults and adolescents in several earlier studies. Nutrient and food group intake and Healthy Eating Index (HEI)-2015 scores were compared among a U.S. nationally representative sample of adolescents (12–19 years, n = 3975) by frequency of consuming food prepared away from home ≤2 times/week (n = 2311) versus >2 times/week (n = 1664) using National Health and Nutrition Examination Survey (NHANES) data from 2011–2018. Regression analyses were used to compare intakes among adolescents by frequency of eating meals prepared away from home adjusting for covariates. Older (16–19 years) vs. younger (12–15 years) adolescents and those from homes with higher vs. lower family income to poverty ratios had greater frequency of eating meals prepared away from home. Intakes of nutrients of concern for adolescents including choline, vitamin D, potassium, magnesium, fiber, phosphorus, folate, iron, and total HEI-2015 scores and component scores for total vegetables, and greens and beans were lower among adolescents who consumed meals prepared away from home more vs. less often. However, no differences were noted among food group intakes considered good sources of nutrients of concern such as total fruit, total vegetables, whole grains, and total dairy, except for beans and peas by frequency of eating foods prepared away from home. Greater frequency of eating foods prepared away from home was associated with lower diet quality among adolescents in a nationally representative sample of U.S. adolescents.

Vitamin D supplementation and cardiometabolic risk factors among diverse schoolchildren: a randomized clinical trial

BACKGROUND

There remains a lack of evidence demonstrating a potential relationship between vitamin D and cardiometabolic risk among children.

OBJECTIVES

We examined the effect of 3 different dosages of vitamin D on cardiometabolic risk factors among children at risk of deficiency.

METHODS

Racially diverse schoolchildren aged 8-15 y were randomly assigned in a double-blind fashion to supplementation with 600, 1000, or 2000 IU vitamin D3/d for 6 mo. Changes in HDL cholesterol, triglycerides, LDL cholesterol, total cholesterol, and blood glucose over 6 mo and at 12 mo (6 mo post-supplementation) were assessed. Subgroup analyses were also performed by weight status and race.

RESULTS

Among 604 children, 40.9% were vitamin D-inadequate at baseline (<20 ng/mL; mean ± SD: 22.0 ± 6.8 ng/mL), 46.4% were overweight/obese, and 60.9% had ≥1 suboptimal blood lipids or glucose. Over 6 mo, serum 25-hydroxyvitamin D increased in all 3 dosage groups from baseline (mean ± SE change: 4.4 ± 0.6 ng/mL, 5.7 ± 0.7 ng/mL, and 10.7 ± 0.6 ng/mL for 600, 1000, and 2000 IU/d, respectively; P < 0.001). Whereas HDL cholesterol and triglycerides increased in the 600 IU group (P = 0.002 and P = 0.02, respectively), LDL cholesterol and total cholesterol decreased across dosage groups. At 6 mo post-supplementation, HDL cholesterol remained elevated in the 600 and 1000 IU groups ( P < 0.001 and P = 0.02, respectively) whereas triglycerides remained elevated in the 1000 and 2000 IU groups (P = 0.04 and P = 0.006, respectively). The suppression of LDL cholesterol and total cholesterol persisted in the 2000 IU group only (P = 0.04 and P < 0.001, respectively). There were no significant changes in blood glucose and similar responses were observed overall by weight status and racial groups across dosages.

CONCLUSIONS

Vitamin D supplementation demonstrated generally positive effects on HDL cholesterol, LDL cholesterol, and total cholesterol, especially at the lower dosage of 600 IU/d, with several significant changes persisting during the post-supplementation period. Increases in triglycerides across dosage groups may be due to natural changes during adolescence warranting further study.This trial was registered at clinicaltrials.gov as NCT01537809.

Vitamin D deficiency in children and adolescents with obesity: a meta-analysis

OBJECTIVE

To evaluate the prevalence of vitamin D deficiency in obese children and adolescents when compared to eutrophic controls.

METHODS

Systematic review with meta-analysis covering studies with patients aged 0-18 years old diagnosed with obesity and vitamin D deficiency and control group of eutrophic patients. The studies were retrieved in the PubMed, Embase, and LILACS databases in December 2019. The search used the terms "obesity" in combination with "pediatric population" and "vitamin D".

RESULTS

Through the search 3155 articles were retrieved; and after analysis, 20 studies were selected according to the study objectives. A total of 24,600 children and adolescents were included. Through meta-analysis, the relative risk for the association between obesity and vitamin D deficiency in the pediatric population was 1.41 (95% CI: 1.26-1.59) (I² = 89%, p < 0.01).

CONCLUSION

Children and adolescents with obesity have higher risk of vitamin D deficiency.

Vitamin D status and cardiometabolic risk factors in Greek adolescents with obesity - the effect of vitamin D supplementation: a pilot study

Introduction

Obesity is associated with cardiovascular disease (CVD) risk factors as well as decreased 25(OH) vitamin D serum levels. We aimed to study 25(OH) vitamin D levels in adolescents with obesity compared with normal weight controls in association with CVD risk factors, and the possible effect of vitamin D supplementation.

Material and methods

In a cross-sectional study, 69 obese and 34 normal-weight adolescents were included. In an interventional study 15 adolescents with obesity and vitamin D insufficiency were given 2000 IU vitamin D per os daily for 3 months.

Results

Adolescents with obesity had significantly lower 25(OH) vitamin D levels compared with normal-weight controls (12.0 (3.0–36.0) vs. 34.0 (10.0–69.0) ng/ml, respectively, p < 0.001). In adolescents with obesity, 25(OH) vitamin D was inversely associated with leptin even after adjustment for body mass index (BMI) (r = –0.340, p = 0.009). Conversely, 25(OH) vitamin D was not related with other parameters, such as BMI, blood pressure, lipids, glucose, insulin, homeostasis model assessment (HOMA) index, adiponectin, leptin/adiponectin ratio, and visfatin levels. Following supplementation in 15 vitamin D insufficient adolescents with obesity, 25(OH) vitamin D significantly increased (from 17.3 (12.5–27.8) to 32.6 (14.3–68.0) ng/ml, p = 0.005) and so did low-density lipoprotein cholesterol (LDL-C) (from 85.4 ±9.5 to 92.1 ±15.8 mg/dl, p = 0.022), while there were reductions in glycated haemoglobin (HbA_1c) (from 5.8 ±0.2 to 5.5 ±0.1%, p = 0.03) and leptin (from 19.7 (7.8–45.5) to 15.1 (4.3–37.3) ng/ml, p = 0.03). Oxidised LDL, paraoxonase, arylesterase, and urine isoprostanes remained unchanged.

Conclusions

Adolescents with obesity had lower 25(OH) vitamin D, which may be associated with higher leptin levels. Vitamin D supplementation may lead to HbA_1c and leptin reductions, but also to an increase in LDL-C.

Logistic LASSO and Elastic Net to Characterize Vitamin D Deficiency in a Hypertensive Obese Population

Aim: The primary objective of our research was to compare the performance of data analysis to predict vitamin D deficiency using three different regression approaches and to evaluate the usefulness of incorporating machine learning algorithms into the data analysis in a clinical setting. Methods: We included 221 patients from our hypertension unit, whose data were collected from electronic records dated between 2006 and 2017. We used classical stepwise logistic regression, and two machine learning methods [least absolute shrinkage and selection operator (LASSO) and elastic net]. We assessed the performance of these three algorithms in terms of sensitivity, specificity, misclassification error, and area under the curve (AUC). Results: LASSO and elastic net regression performed better than logistic regression in terms of AUC, which was significantly better in both penalized methods, with AUC = 0.76 and AUC = 0.74 for elastic net and LASSO, respectively, than in logistic regression, with AUC = 0.64. In terms of misclassification rate, elastic net (18%) outperformed LASSO (22%) and logistic regression (25%). Conclusion: Compared with a classical logistic regression approach, penalized methods were found to have better performance in predicting vitamin D deficiency. The use of machine learning algorithms such as LASSO and elastic net may significantly improve the prediction of vitamin D deficiency in a hypertensive obese population.

Obesity and Vitamin D Insufficiency among Adolescent Girls and Young Adult Women from Korea

Although there is evidence of the biological mechanisms by which obesity may induce vitamin D insufficiency or deficiency, limited epidemiological studies have been conducted, especially among Asian adolescent girls and young adult women who are at a high risk of vitamin D deficiency. This study aimed to examine the cross-sectional association between obesity and vitamin D insufficiency among adolescent girls and young adult women in Korea. We used data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2008–2014, and 3623 girls and young adult women aged 12–29 years were included. Demographic and lifestyle data were collected using a self-administered questionnaire from the health interview survey. Serum 25-hydroxyvitamin D (25(OH)D) level, body mass index (BMI), and body fat percentage (BF%) were measured during health examinations. Multivariable logistic regression was used considering the complex, multistage probability sample design of KNHANES. In the multivariable-adjusted analyses, obese girls and women, defined by BMI, were more likely to have a higher prevalence of vitamin D insufficiency (odds ratio [OR]: 1.49, 95% confidence interval [CI]: 1.03–2.17). This association was also evident for BF%. Participants with ≥30% BF% had a significantly higher prevalence of vitamin D insufficiency (OR: 1.52, 95% CI: 1.07–2.16). Obesity may worsen vitamin D insufficiency among adolescents and young women because of the fat-soluble characteristics of vitamin D and related health behaviors, such as a lack of outdoor activity. Further large-scale prospective cohort studies or randomized controlled trials are warranted to confirm this causality.

Serum 25-Hydroxyvitamin D, Plasma Lipids, and Associated Gene Variants in Prepubertal Children

CONTEXT

The associations of serum 25-hydroxyvitamin D [25(OH)D] with plasma lipids remain controversial in children.

OBJECTIVE

To examine the associations and interactions of 25(OH)D and related gene variants with lipids in children.

DESIGN

Cross-sectional.

SETTING

Kuopio, Finland.

PARTICIPANTS

Population sample of 419 prepubertal white children aged 6 to 8 years.

MAIN OUTCOME MEASURES

25(OH)D, total cholesterol, low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, and triglycerides.

RESULTS

Serum 25(OH)D was negatively associated with total cholesterol (β = -0.141, P = 0.004), LDL cholesterol (β = -0.112, P = 0.023), HDL cholesterol (β = -0.150, P = 0.002), and triglycerides (β = -0.104, P = 0.035) adjusted for age and sex. Associations of 25(OH)D with total cholesterol, LDL cholesterol, and HDL cholesterol remained after adjustment for adiposity, physical activity, sedentary behavior, diet, daylight time, and parental education. Children in the highest quartile of 25(OH)D had the lowest total cholesterol (P = 0.022) and LDL cholesterol (P = 0.026) adjusted for age and sex. Cytochrome P450 family 2 subfamily R member 1 (CYP2R1) rs12794714, CYP2R1 rs10741657, and vitamin D binding protein (DBP) rs2282679 were associated with 25(OH)D adjusted for age and sex. CYP2R1 rs12794714 was associated with total cholesterol and LDL cholesterol and C10orf88 rs6599638 with HDL cholesterol adjusted for age, sex, and 25(OH)D. The gene variants did not explain or modify the associations of 25(OH)D with lipids.

CONCLUSIONS

25(OH)D was independently and inversely associated with total cholesterol, LDL cholesterol, and HDL cholesterol. CYP2R1 rs12794714, CYP2R1 rs10741657, and DBP rs2282679 were associated with 25(OH)D. CYP2R1 rs12794714 was associated with total cholesterol and LDL cholesterol and chromosome 10 open reading frame 88 (C10orf88) rs6599638 with HDL cholesterol independent of 25(OH)D. None of the gene variants modified the associations of 25(OH)D with lipids. Further studies are needed to detect the mechanisms for the associations of 25(OH)D with lipids.

Current Evidence on Vitamin D Deficiency and Metabolic Syndrome in Obese Children: What Does the Evidence from Saudi Arabia Tell Us?

Obesity and vitamin D deficiency represent major health problems among Saudi children, and have been linked to chronic diseases. Obese children are at risk of developing vitamin D deficiency, which appears to have negative influences on energy homeostasis, impeded bone mineralisation, insulin resistance and inflammation. Evidence supporting the association between vitamin D deficiency of obese children and metabolic syndrome has not specifically been studied in early childhood. The mechanisms through which vitamin D deficiency is associated with metabolic syndrome in obese children needs further elucidation. This commentary aims to (i) summarise current knowledge of the association between vitamin D deficiency and metabolic syndrome in obese children; and (ii) discuss current evidence for the association among Saudi Arabian children.

Vitamin D and cardiovascular diseases: Causality

Vitamin D regulates blood pressure, cardiac functions, and endothelial and smooth muscle cell functions, thus, playing an important role in cardiovascular health. Observational studies report associations between vitamin D deficiency with hypertension and cardiovascular-related deaths. Peer-reviewed papers were examined in several research databases as per the guidelines of the Preferred Reporting Items for Systematic Reviews, using key words that address the relationship between vitamin D and cardiovascular disease. Correlations and interpretations were made considering the risks-benefits, broader evidence, and implications. This review analyzed current knowledge regarding the effects of vitamin D on the cardiovascular system. 1,25(OH)₂D and related epigenetic modifications subdue cellular inflammation, improve overall endothelial functions, reduce age-related systolic hypertension and vascular rigidity, and attenuate the actions of the renin-angiotensin-aldosterone system. Most observational and ecological studies support 25(OH)vitamin D having protective effects on the cardiovascular system. However, the association of vitamin D deficiency with cardiovascular diseases is based primarily on observational and ecological studies and thus, is a matter of controversy. Adequately powered, randomized controlled clinical trial data are not available to confirm these associations. Thus, to test the hypothesis that correction of vitamin D deficiency protects the cardiovascular system, well-designed, statistically powered, longer-term clinical trials are needed in persons with vitamin D deficiency. Nevertheless, the available data support that adequate vitamin D supplementation and/or sensible sunlight exposure to achieve optimal vitamin D status are important in the prevention of cardiovascular disease and other chronic diseases.

Associations of vitamin D with insulin resistance, obesity, type 2 diabetes, and metabolic syndrome

The aim of this study is to determine the relationships of vitamin D with diabetes, insulin resistance obesity, and metabolic syndrome. Intra cellular vitamin D receptors and the 1-α hydroxylase enzyme are distributed ubiquitously in all tissues suggesting a multitude of functions of vitamin D. It plays an indirect but an important role in carbohydrate and lipid metabolism as reflected by its association with type 2 diabetes (T2D), metabolic syndrome, insulin secretion, insulin resistance, polycystic ovarian syndrome, and obesity. Peer-reviewed papers, related to the topic were extracted using key words, from PubMed, Medline, and other research databases. Correlations of vitamin D with diabetes, insulin resistance and metabolic syndrome were examined for this evidence-based review. In addition to the well-studied musculoskeletal effects, vitamin D decreases the insulin resistance, severity of T2D, prediabetes, metabolic syndrome, inflammation, and autoimmunity. Vitamin D exerts autocrine and paracrine effects such as direct intra-cellular effects via its receptors and the local production of 1,25(OH)₂D₃, especially in muscle and pancreatic β-cells. It also regulates calcium homeostasis and calcium flux through cell membranes, and activation of a cascade of key enzymes and cofactors associated with metabolic pathways. Cross-sectional, observational, and ecological studies reported inverse correlations between vitamin D status with hyperglycemia and glycemic control in patients with T2D, decrease the rate of conversion of prediabetes to diabetes, and obesity. However, no firm conclusions can be drawn from current studies, because (A) studies were underpowered; (B) few were designed for glycemic outcomes, (C) the minimum (or median) serum 25(OH) D levels achieved are not measured or reported; (D) most did not report the use of diabetes medications; (E) some trials used too little (F) others used too large, unphysiological and infrequent doses of vitamin D; and (G) relative paucity of rigorous clinical data on the effects of vitamin D sufficiency on non-calcium endpoints. Although a large number of observational studies support improving T2D, insulin resistance, obesity, and metabolic syndrome with vitamin D adequacy, there is a lack of conclusive evidence from randomized control clinical trials that, these disorders are prevented following optimization of serum levels of 25(OH)D. However, none of the currently conducted clinical studies would resolve these issues. Thus, specifically designed, new clinical studies are needed to be conducted in well-defined populations, following normalizing the serum vitamin D levels in vitamin D deficient prediabetes subjects, to test the hypothesis that hypovitaminosis D worsens these disorders and correction would alleviate it.

Impact of Three Doses of Vitamin D3 on Serum 25(OH)D Deficiency and Insufficiency in At-Risk Schoolchildren

OBJECTIVE

We investigated the daily dose of vitamin D needed to achieve serum 25-hydroxyvitamin D [25(OH)D] sufficiency among schoolchildren at risk for deficiency.

STUDY DESIGN

The Daily D Health Study was a randomized double-blind vitamin D supplementation trial among racially/ethnically diverse schoolchildren (n = 685) in the northeastern United States. Children were supplemented with vitamin D3 at 600, 1000, or 2000 IU/d for 6 months. Measurements included serum 25(OH)D at baseline (October to December), 3 months (January to March), 6 months (April to June), and 12 months (6 months after supplementation).

RESULTS

At baseline, mean ± standard deviation serum 25(OH)D level was 22.0 ± 6.8 ng/mL, with 5.5% severely vitamin D deficient (<12 ng/mL), 34.1% deficient (12 to 19 ng/mL), 49.0% insufficient (20 to 29 ng/mL), and 11.4% sufficient (≥30 ng/mL). The lowest levels of serum 25(OH)D were found among black (17.9 ± 6.7 ng/mL) and Asian children (18.9 ± 4.8 ng/mL), with no baseline differences by weight status. Serum 25(OH)D increased over 6 months in all three dose groups. The 2000 IU/d group achieved a higher mean serum 25(OH)D level than the other two dose groups (33.1 vs 26.3 and 27.5 ng/mL; P < 0.001), with 59.9% of this group attaining sufficiency at 3 months and only 5.3% remaining severely deficient/deficient at 6 months. All dose groups demonstrated a fall in 25(OH)D at 12 months.

CONCLUSIONS

Children at risk for vitamin D deficiency benefited from daily sustained supplementation of 2000 IU/d compared with lower doses closer to the current recommended daily allowance for vitamin D intake. This benefit occurred over the winter months, when serum 25(OH)D level tend to fall.

Vitamin D Deficiency: A Potential Modifiable Risk Factor for Cardiovascular Disease in Children with Severe Obesity

Severe obesity is associated with abnormal lipids and increased risk for cardiovascular disease. Obesity is a risk factor for vitamin D deficiency. We examined relationship between 25-hydroxy vitamin D (25(OH)D) concentrations and lipids in children with severe obesity. Medical records of 376 children were reviewed. Linear regression models and logistic regression were used to examine the relationship between 25(OH)D and lipids after adjustment for age, gender, season of blood draw, body mass index (BMI) z-score, and BMI % of 95th percentile. Two-hundred sixty-three out of 376 children (70%) had 25(OH)D concentrations < 30 ng/mL. Concentrations of 25(OH)D were positively correlated with those of high-density lipoprotein cholesterol (HDL-C) (r² = 0.08, r = 0.22, β = 0.16, 95% CI = 0.05–0.27, p = 0.004). HDL-C was lower in children with 25(OH)D < 30 ng/mL (n = 263) compared to those with 25(OH)D ≥ 30 ng/mL (n = 113) (41.3 ± 10.2 vs. 46.4 ± 12 mg/dL, p < 0.0001). Children with 25(OH)D concentrations < 30 ng/mL had greater adjusted odds of low HDL-C (<40 mg/dL) compared with those with 25(OH)D ≥ 30 ng/mL (47.9% vs. 29.2%, OR 2.15 (1.33–3.51), p = 0.0019). Total cholesterol and non-HDL-C were not correlated with 25(OH)D concentrations. Vitamin D deficiency is highly prevalent in children with severe obesity. Prospective clinical trials are warranted to determine if vitamin D supplementation can improve HDL-C and potentially decrease risk for cardiovascular disease in children with obesity.

The vitamin D deficiency pandemic: Approaches for diagnosis, treatment and prevention

Vitamin D deficiency and insufficiency is a global health issue that afflicts more than one billion children and adults worldwide. The consequences of vitamin D deficiency cannot be under estimated. There has been an association of vitamin D deficiency with a myriad of acute and chronic illnesses including preeclampsia, childhood dental caries, periodontitis, autoimmune disorders, infectious diseases, cardiovascular disease, deadly cancers, type 2 diabetes and neurological disorders. This review is to put into perspective the controversy surrounding the definition for vitamin D deficiency and insufficiency as well as providing guidance for how to treat and prevent vitamin D deficiency.

A predictive model for lack of partial clinical remission in new-onset pediatric type 1 diabetes

IMPORTANCE

>50% of patients with new-onset type 1 diabetes (T1D) do not enter partial clinical remission (PCR); early identification of these patients may improve initial glycemic control and reduce long-term complications.

AIM

To determine whether routinely obtainable clinical parameters predict non-remission in children and adolescents with new-onset T1D.

SUBJECTS AND METHODS

Data on remission were collected for the first 36 months of disease in 204 subjects of ages 2-14 years with new-onset type 1 diabetes. There were 86 remitters (age 9.1±3.0y; male 57%), and 118 non-remitters (age 7.0±3.1y; male 40.7%). PCR was defined as insulin-dose adjusted hemoglobin A1c of ≤9.

RESULTS

Non-remission occurred in 57.8% of subjects. Univariable analysis showed that the risk for non-remission was increased 9-fold in patients with 4 diabetes-associated auto-antibodies (OR = 9.90, p = 0.010); 5-fold in patients <5 years old (odds ratio = 5.38, p = 0.032), 3-fold in those with bicarbonate of <15 mg/dL at diagnosis (OR = 3.71, p = 0.008). Combined estimates of risk potential for HC03 and the number of autoantibodies by multivariable analysis, adjusted for BMI standard deviation score, showed HC03 <15 mg/dL with a clinically significant 10-fold risk (OR = 10.1, p = 0.074); and the number of autoantibodies with a 2-fold risk for non-remission (OR = 1.9, p = 0.105). Male sex and older age were associated with decreased risk for non-remission. A receiver-operating characteristic curve model depicting sensitivity by 1-specificity for non-remission as predicted by bicarbonate <15 mg/dL, age <5y, female sex, and >3 diabetes-associated autoantibodies had an area under the curve of 0.73.

CONCLUSIONS

More than 50% of children and adolescents with new-onset T1D do not undergo partial clinical remission and are thus at an increased risk for long-term complications of diabetes mellitus. A predictive model comprising of bicarbonate <15 mg/dL, age <5y, female sex, and >3 diabetes-associated autoantibodies has 73% power for correctly predicting non-remission in children and adolescents with new-onset T1D. Early identification of these non-remitters may guide the institution of targeted therapy to limit dysglycemia and reduce the prevalence of long-term deleterious complications.

Vitamin D status in pediatric irritable bowel syndrome

Importance

Irritable bowel syndrome (IBS) is associated with significant morbidity in children and adolescents, and the therapeutic efficacy of available treatment options is limited. The role of vitamin D supplementation in pediatric IBS is unclear as the vitamin D status of pediatric patients with IBS is unknown. Equally, the relationship of vitamin D status with psychosomatic symptoms in children and adolescents is unclear.

Aim

To characterize the vitamin D status of pediatric patients with IBS using a case-control study design.

Hypothesis

Serum 25-hydroxyvitamin D [25(OH)D] concentration will be similar between patients with IBS and controls.

Subjects and methods

A retrospective case-controlled study of 116 controls (age 14.6 ± 4.3 y), female (n = 67; 58%) and 55 subjects with IBS (age 16.5 ± 3.1y), female (n = 44; 80%). Overweight was defined as BMI of ≥85^th but <95^th percentile, and obesity as BMI ≥95^th percentile. Vitamin D deficiency was defined as 25(OH)D of <50 nmol/L, while seasons of vitamin D draw were categorized as summer, winter, spring, and fall. Major psychosomatic manifestations included in the analysis were depression, anxiety, and migraine.

Results

More than 50% of IBS subjects had vitamin D deficiency at a cut-off point of <50 nmol/L (53% vs. 27%, p = 0.001); and >90% of IBS subjects had vitamin D deficiency at a cut-off point of <75 nmol/L (93% vs. 75%, p = 0.006). IBS subjects had significantly lower mean 25(OH)D: 53.2 ± 15.8 nmol/L vs. 65.2 ± 28.0 nmol/L, p = 0.003; and albumin: 6.2 ± 0.6 vs. 6.5 ± 0.6 μmol/L, p = 0.0.01. IBS subjects with migraine had significantly lower mean 25(OH)D concentration compared to controls (p = 0.01). BMI z-score was similar between the controls and IBS subjects (0.5 ± 1.4 vs. 1.2 ± 2.9, p = 0.11).

Conclusions

Pediatric patients with IBS had significantly lower 25(OH)D concentration compared to controls despite having similar mean BMI values as controls. Only 7% of the children and adolescents with IBS were vitamin D sufficient, and >50% of the subjects with IBS had vitamin D deficiency. This is a much higher prevalence of vitamin D deficiency compared to IBD and other malabsorption syndromes. Monitoring for vitamin D deficiency should be part of the routine care for patients with IBS. Randomized control trials are warranted to determine the role of adjunctive vitamin D therapy in pediatric IBS.

Vitamin D inadequacy is widespread in Tunisian active boys and is related to diet but not to adiposity or insulin resistance

BACKGROUND

Vitamin D inadequacy is widespread in children and adolescents worldwide. The present study was undertaken to assess the vitamin D status in active children living in a sunny climate and to identify the main determinants of the serum concentration of 25-hydroxyvitamin D (25-OHD).

METHODS

This cross-sectional study included 225 children aged 7-15 years practicing sports in a football academy. Anthropometric measures were performed to calculate body mass index (BMI), fat mass, and maturity status. A nutritional enquiry was performed including 3-day food records and food frequency questionnaire. Plasma 25-OHD and insulin were assessed by immunoenzymatic methods ensuring categorization of vitamin D status and calculation of insulin sensitivity/resistance indexes. A logistic regression model was applied to identify predictors for vitamin D inadequacy.

RESULTS

Vitamin D deficiency (25-OHD<12 µg/L) was observed in 40.9% of children and insufficiency (12<25-OHD<20 µg/L) was observed in 44% of children. In a multivariate analysis, vitamin D deficiency and insufficiency were associated with a lower dietary intake of vitamin D, proteins, milk, red meat, fish, and eggs. However, no significant relationship was observed with maturation status, adiposity, or insulin resistance.

CONCLUSIONS

Tunisian children and adolescents are exposed to a high risk of vitamin D inadequacy despite living in a sunny climate. Circulating 25-OHD concentrations are related to the intake of vitamin D food sources but not to maturation status or body composition. Ensuring sufficient and safe sun exposure and adequate vitamin D intake may prevent vitamin D inadequacy in children from sunny environments.

Sun-Exposed Skin Color Is Associated with Changes in Serum 25-Hydroxyvitamin D in Racially/Ethnically Diverse Children

BACKGROUND

UVB light from the sun increases serum 25-hydroxyvitamin D [25(OH)D] concentration, but this relation may depend on skin pigmentation among different racial/ethnic groups.

OBJECTIVE

We used quantitative measures of exposed (facultative) and unexposed (constitutive) skin color to examine relations between serum 25(OH)D concentration, tanning, race/ethnicity, and constitutive skin color over the summer, following winter vitamin D supplementation.

METHODS

The subjects (n= 426, mean age 11.7 ± 1.4 y, 51% female) were racially/ethnically diverse schoolchildren (57% non-white/Caucasian) enrolled in a 6-mo vitamin D supplementation trial (October-December to April-June). In this secondary analysis, measures of serum 25(OH)D concentration and skin color, with the use of reflectance colorimetry, were taken over a 6-mo period after supplementation, from pre-summer (April-June) to post-summer (September-December). Multiple linear regression was used to evaluate longitudinal relations.

RESULTS

Following supplementation, mean serum 25(OH)D concentration was 29.3 ± 9.5 ng/mL but fell to 25.6 ± 7.9 ng/mL (P< 0.0001) by the end of summer. The decrease in white/Caucasian children was less than in black/African American children (P< 0.01) and tended to be less than in Hispanic/Latino, Asian, and multiracial/other children (P= 0.19-0.50) despite similar changes in sun-exposed skin color among all groups. Tanning was significantly associated with post-summer serum 25(OH)D concentration (β = -0.15,P< 0.0001), as was race/ethnicity (P= 0.0002), but the later association disappeared after adjusting for constitutive skin color.

CONCLUSIONS

Tanning significantly contributed to serum 25(OH)D concentration over the summer, independent of race/ethnicity, but was not sufficient to maintain serum 25(OH)D concentration attained with supplementation. Much of the variation in serum 25(OH)D concentration between racial/ethnic groups may be explained by skin color. This trial was registered atclinicaltrials.govasNCT01537809.

Vitamin D status is associated with cardiometabolic markers in 8-11-year-old children, independently of body fat and physical activity

Vitamin D status has been associated with cardiometabolic markers even in children, but the associations may be confounded by fat mass and physical activity behaviour. This study investigated associations between vitamin D status and cardiometabolic risk profile, as well as the impact of fat mass and physical activity in Danish 8-11-year-old children, using baseline data from 782 children participating in the Optimal well-being, development and health for Danish children through a healthy New Nordic Diet (OPUS) School Meal Study. We assessed vitamin D status as serum 25-hydroxyvitamin D (25(OH)D) and measured blood pressure, fasting plasma glucose, homoeostasis model of assessment-insulin resistance, plasma lipids, inflammatory markers, anthropometry and fat mass by dual-energy X-ray absorptiometry, and physical activity by 7 d accelerometry during August-November. Mean serum 25(OH)D was 60·8 (sd 18·7) nmol/l. Each 10 mmol/l 25(OH)D increase was associated with lower diastolic blood pressure (-0·3 mmHg, 95 % CI -0·6, -0·0) (P=0·02), total cholesterol (-0·07 mmol/l, 95 % CI -0·10, -0·05), LDL-cholesterol (-0·05 mmol/l, 95 % CI -0·08, -0·03), TAG (-0·02 mmol/l, 95 % CI -0·03, -0·01) (P≤0·001 for all lipids) and lower metabolic syndrome (MetS) score (P=0·01). Adjustment for fat mass index did not change the associations, but the association with blood pressure became borderline significant after adjustment for physical activity (P=0·06). In conclusion, vitamin D status was negatively associated with blood pressure, plasma lipids and a MetS score in Danish school children with low prevalence of vitamin D deficiency, and apart from blood pressure the associations were independent of body fat and physical activity. The potential underlying cause-effect relationship and possible long-term implications should be investigated in randomised controlled trials.

Association between Vitamin D and Circulating Lipids in Early Childhood

Vitamin D is associated with established cardiovascular risk factors such as low density lipoprotein (LDL) in adults. It is unknown whether these associations are present in early childhood. To determine whether serum 25-hydroxyvitamin D (25(OH)D) is associated with serum non-high density lipoprotein (non-HDL) cholesterol during early childhood we conducted a cross-sectional study of children aged 1 to 5 years. Healthy children were recruited through the TARGet Kids! practice based research network from 2008-2011 (n=1,961). The associations between 25(OH)D and non-fasting non-HDL cholesterol (the primary endpoint), total cholesterol, triglycerides, HDL, and low density lipoprotein (LDL) cholesterol, were evaluated using multiple linear regression adjusted for age, sex, skin pigmentation, milk intake, vitamin D supplementation, season, body mass index, outdoor play, and screen time. Each 10 nmol/L increase in 25(OH)D was associated with a decrease in non-HDL cholesterol concentration of -0.89 mg/dl (95% CI: -1.16,-0.50), total cholesterol of -1.08 mg/dl (95%CI: -1.49,-0.70), and triglycerides of -2.34 mg/dl (95%CI: -3.23,-1.45). The associations between 25(OH)D and LDL and HDL were not statistically significant. 25(OH)D concentrations were inversely associated with circulating lipids in early childhood, suggesting that vitamin D exposure in early life may be an early modifiable risk factor for cardiovascular disease.

Obesity and vitamin D deficiency: a systematic review and meta-analysis

Over the past decade, there have been an increasing number of studies on the association between vitamin D deficiency and anthropometric state. However, we did not identify any meta-analyses of the relationship between obesity and vitamin D deficiency in different age groups. Thus, we evaluated the association between obesity and vitamin D deficiency. We searched for observational studies published up to April 2014 in PubMed/Medline, Web of Science and Scopus databases. We performed a meta-analysis in accordance with the random-effects model to obtain the summary measurement (prevalence ratio, PR). Among the 29,882 articles identified, 23 met the inclusion criteria. The prevalence of vitamin D deficiency was 35% higher in obese subjects compared to the eutrophic group (PR: 1.35; 95% CI: 1.21-1.50) and 24% higher than in the overweight group (PR: 1.24; 95% CI: 1.14-1.34). These results indicate that the prevalence of vitamin D deficiency was more elevated in obese subjects. The vitamin D deficiency was associated with obesity irrespective of age, latitude, cut-offs to define vitamin D deficiency and the Human Development Index of the study location.

Increased risk for vitamin d deficiency in obese children with both celiac disease and type 1 diabetes

Background. It is unknown whether the coexistence of type 1 diabetes (T1D) and celiac disease (CD) increases the risk for vitamin D deficiency. Aims. To determine the vitamin D status and the risk for vitamin D deficiency in prepubertal children with both T1D and CD compared to controls, TID, and CD. Subjects and Methods. Characteristics of 62 prepubertal children of age 2–13 y with either CD + T1D (n = 22, 9.9 ± 3.1 y), CD only (n = 18, 8.9 ± 3.3 y), or T1D only (n = 22, 10.1 ± 2.8 y) were compared to 49 controls of the age of 8.0 ± 2.6 years. Vitamin D deficiency was defined as 25(OH)D < 50 nmol/L, overweight as BMI of >85th but <95th percentile, and obesity as BMI > 95th percentile. Results. The 4 groups had no difference in 25(OH)D (ANOVA P = 0.123) before stratification into normal-weight versus overweight/obese subtypes. Following stratification, 25(OH)D differed significantly between the subgroups (F_(3,98) = 10.109, ANOVA P < 0.001). Post-hoc analysis showed a significantly lower 25(OH)D in the overweight/obese CD + T1D compared to the overweight/obese controls (P = 0.039) and the overweight/obese CD (P = 0.003). Subjects with CD + T1D were 3 times more likely to be vitamin D deficient (OR = 3.1 [0.8–11.9], P = 0.098), compared to controls. Conclusions. The coexistence of T1D and CD in overweight/obese prepubertal children may be associated with lower vitamin D concentration.

Association of serum 25-hydroxyvitamin D with race/ethnicity and constitutive skin color in urban schoolchildren

The objective of this study was to determine the extent to which constitutive skin color explains racial/ethnic differences in serum 25-hydroxyvitamin D (25OHD) concentrations in urban schoolchildren. Analysis of covariance (ANCOVA) was used to determine associations of 25OHD with parent-reported race/ethnicity and constitutive skin color as measured by reflectance colorimeter [individual typology angle (ITA°; higher value corresponds to lighter skin)] in 307 Greater Boston schoolchildren aged 9-15 during October-December 2011. Nearly 60% of all children were inadequate in 25OHD (<20 ng/mL). Prevalence of inadequate 25OHD differed by race/ethnicity (p<0.001): white (46.6%), black (74.5%), Hispanic (64.7%), Asian (88.9%), and multi-racial/other (52.7%). Serum 25OHD increased 0.6 ng/mL per 10° increase in ITA° value (p<0.001). The prediction of 25OHD by race/ethnicity was slightly stronger than the prediction by skin color in separate models (R2=0.19, R2=0.16, respectively). Most of the variability in 25OHD in race/ethnicity was due to constitutive skin color in this group of racially diverse US children.

Recruitment and retention of urban schoolchildren into a randomized double-blind vitamin D supplementation trial

BACKGROUND

While rarely used for supplementation trials in the United States, schools present a practical alternative to a clinical setting.

PURPOSE

We describe the successful recruitment and retention of urban schoolchildren into a 6-month randomized, double-blind vitamin D3 supplementation trial.

METHODS

Boston-area urban schoolchildren, aged 8-15 years, were recruited in 2011-2012 through classroom and auditorium presentations. Informed consent forms in five languages were sent home to parents. Retention methods included regular telephone calls and gift cards for completed study visits.

RESULTS

In total, 691 schoolchildren enrolled. Their mean (standard deviation) age was 11.7 (1.4) years; 59% were racial/ethnic minorities and 68% qualified for free or reduced-price school meals. Multi-level, culturally sensitive, creative approaches contributed to success in recruitment and retention. Of 691 participants, 81% completed the 6-month intervention period. Reasons for attrition included missed appointments and fear of a blood draw. More children from households with higher incomes were retained than those from households with lower incomes (85% vs 79%, respectively, P = 0.04).

LIMITATIONS

The need for three fasting blood draws over the 6-month supplementation period was a limiting factor in the recruitment and retention of children in this study.

CONCLUSION

Recruitment of urban children into a school-based randomized controlled trial represents a feasible approach for a supplementation study. Particular attention to children of lower socioeconomic status may enhance participation and retention when conducting intervention studies among diverse populations.

The vitamin D status in inflammatory bowel disease

CONTEXT

There is no consensus on the vitamin D status of children and adolescents with inflammatory bowel disease (IBD).

AIM

To determine the vitamin D status of patients with IBD by comparing their serum 25(OH)D concentration to that of healthy controls.

HYPOTHESIS

Serum 25(OH)D concentration will be lower in patients with IBD compared to controls.

SUBJECTS AND METHODS

A case-controlled retrospective study of subjects with IBD (n = 58) of 2-20 years (male n = 31, age 16.38±2.21 years; female n = 27, age 16.56±2.08 years) and healthy controls (n = 116; male n = 49, age 13.90±4.59 years; female n = 67, age 15.04±4.12 years). Study subject inclusion criteria: diagnosis of Crohn's disease (CD) or ulcerative colitis (UC). Vitamin D deficiency was defined as 25(OH)D of (<20 ng/mL) (<50 nmol/L), overweight as BMI of ≥85th but <95th percentile, and obesity as BMI ≥95th percentile. Data were expressed as mean ± SD.

RESULTS

Patients with CD, UC, and their controls had mean serum 25(OH)D concentrations of 61.69±24.43 nmol/L, 53.26±25.51, and 65.32±27.97 respectively (ANOVA, p = 0.196). The overweight/obese controls had significantly lower 25(OH)D concentration compared to the normal-weight controls (p = 0.031); whereas 25(OH)D concentration was similar between the normal-weight and overweight/obese IBD patients (p = 0.883). There was no difference in 25(OH)D between patients with UC and CD, or between subjects with active IBD and controls. However, IBD subjects with elevated ESR had significantly lower 25(OH)D than IBD subjects with normal ESR (p = 0.025), as well as controls (65.3±28.0 nmol/L vs. 49.5±25.23, p = 0.045).

CONCLUSION

There is no difference in mean serum 25(OH)D concentration between children and adolescents with IBD and controls. However, IBD subjects with elevated ESR have significantly lower 25(OH)D than controls. Therefore, IBD subjects with elevated ESR should be monitored for vitamin D deficiency.

The association of vitamin D status with cardiometabolic risk factors, obesity and puberty in children

Low serum 25-hydroxyvitamin D3 (25(OH)D) levels have been associated with insulin resistance and cardiovascular diseases. The influences of gender, puberty and adiposity on vitamin D status and the relationship between 25(OH)D and cardiometabolic risk factors in obese and non-obese children were studied. A retrospective analysis was carried out on 168 Turkish children during late winter. Age, gender, puberty, body mass index (BMI), 25(OH)D levels and cardiometabolic risk factors including lipid profiles, high-sensitivity C-reactive protein and insulin resistance index calculated by homeostasis model assessment (HOMA-IR) were evaluated. The median age of the study population was 11 (4-16) years, and 102 children (60.7 %) were prepubertal. Overall, 98.2 % of patients had 25(OH)D levels lower than 20 ng/mL (median 10.0 (4.0-21.3) ng/mL). The 25(OH)D levels did not correlate with BMI. However, an inverse correlation was seen between serum 25(OH)D and HOMA-IR (rho = -0.656, p = 0.006) and insulin (rho = -0.715, p = 0.002) in pubertal obese subjects. Female gender and puberty were all negatively associated with 25(OH)D.

CONCLUSION

The association between vitamin D status and BMI is complex, and it does not seem to be altered by mild obesity. In addition, potential influence of puberty should be kept in mind while assessing the relationship between serum 25(OH)D and cardiometabolic risk factors.

From cholesterogenesis to steroidogenesis: role of riboflavin and flavoenzymes in the biosynthesis of vitamin D

Flavin-dependent monooxygenases and oxidoreductases are located at critical branch points in the biosynthesis and metabolism of cholesterol and vitamin D. These flavoproteins function as obligatory intermediates that accept 2 electrons from NAD(P)H with subsequent 1-electron transfers to a variety of cytochrome P450 (CYP) heme proteins within the mitochondria matrix (type I) and the (microsomal) endoplasmic reticulum (type II). The mode of electron transfer in these systems differs slightly in the number and form of the flavin prosthetic moiety. In the type I mitochondrial system, FAD-adrenodoxin reductase interfaces with adrenodoxin before electron transfer to CYP heme proteins. In the microsomal type II system, a diflavin (FAD/FMN)-dependent cytochrome P450 oxidoreductase [NAD(P)H-cytochrome P450 reductase (CPR)] donates electrons to a multitude of heme oxygenases. Both flavoenzyme complexes exhibit a commonality of function with all CYP enzymes and are crucial for maintaining a balance of cholesterol and vitamin D metabolites. Deficits in riboflavin availability, imbalances in the intracellular ratio of FAD to FMN, and mutations that affect flavin binding domains and/or interactions with client proteins result in marked structural alterations within the skeletal and central nervous systems similar to those of disorders (inborn errors) in the biosynthetic pathways that lead to cholesterol, steroid hormones, and vitamin D and their metabolites. Studies of riboflavin deficiency during embryonic development demonstrate congenital malformations similar to those associated with genetic alterations of the flavoenzymes in these pathways. Overall, a deeper understanding of the role of riboflavin in these pathways may prove essential to targeted therapeutic designs aimed at cholesterol and vitamin D metabolism.

Attitudes and beliefs toward biobehavioural research participation: voices and concerns of urban adolescent females receiving outpatient mental health treatment

BACKGROUND

Biobehavioural research methodology can be invasive and burdensome for participants - particularly adolescents with mental illnesses. Human biological researchers should consider how methodological impositions may hinder adolescent research participation. However, literature on adolescent's voices and concerns toward biobehavioural research participation is virtually non-existent.

AIM

This study was designed to determine adolescents' perceptions of participation in research involving the collection of biomarkers via blood, saliva and/or urine samples.

SUBJECTS AND METHODS

Urban adolescent females (aged 12-19) receiving outpatient mental health treatment (n = 37) participated in focus groups with concurrent survey administration to explore attitudes, beliefs and willingness/intentions toward biobehavioural research participation.

RESULTS

Participants had favourable attitudes toward biobehavioural research and were amenable to provide each specimen type. Mistrust for research emerged, however, and concerns related to privacy and confidentiality were expressed.

CONCLUSION

Participant recruitment is a critical component in study design and implementation; this includes knowledge of population-specific recruitment barriers and facilitators. This innovative paper provides a context for the research participants' decision-making process, strategies to allay fears and concerns and concrete areas to target in research-related interventions. Although the findings are from a specific, US-based sample, the implications warrant replication of the research in other geosocial settings.

Lactose intolerance: lack of evidence for short stature or vitamin D deficiency in prepubertal children

BACKGROUND

The health consequences of lactose intolerance (LI) are unclear.

AIMS

To investigate the effects of LI on stature and vitamin D status.

HYPOTHESES

LI subjects will have similar heights and vitamin D status as controls.

SUBJECTS AND METHODS

Prepubertal children of ages 3-12 years with LI (n=38, age 8.61 ± 3.08y, male/female 19/19) were compared to healthy, age- and gender-matched controls (n=49, age 7.95±2.64, male/female 28/21).

INCLUSION CRITERIA

prepubertal status (boys: testicular volume <3cc; girls: Tanner 1 breasts), diagnosis of LI by hydrogen breath test, and no history of calcium or vitamin D supplementation. Vitamin D deficiency was defined as 25-hydroxyvitamin D [25(OH)D] <50 nmol/L. Gender-adjusted midparental target height (MPTH) z-score was calculated using NCHS data for 18 year-old adults. Data were expressed as mean ± SD.

RESULTS

There was no significant difference in 25(OH)D between the LI and non-LI subjects (60.1±21.1, vs. 65.4 ± 26.1 nmol/L, p = 0.29). Upon stratification into normal weight (BMI <85(th) percentile) vs. overweight/obese (BMI ≥85(th) percentile), the normal weight controls had significantly higher 25(OH)D level than both the normal weight LI children (78.3 ± 32.6 vs. 62.9 ± 23.2, p = 0.025), and the overweight/obese LI children (78.3±32.6 vs. 55.3±16.5, p = 0.004). Secondly, there was no overall difference in height z-score between the LI children and controls. The normal weight LI patients had similar height as normal controls (-0.46 ± 0.89 vs. -0.71 ± 1.67, p = 0.53), while the overweight/obese LI group was taller than the normal weight controls (0.36 ± 1.41 vs. -0.71 ± 1.67, p = 0.049), and of similar height as the overweight/obese controls (0.36 ± 1.41 vs. 0.87 ± 1.45, p = 0.28). MPTH z-score was similar between the groups.

CONCLUSION

Short stature and vitamin D deficiency are not features of LI in prepubertal children.

Vitamin d in pediatric inpatients with respiratory illnesses

BACKGROUND AND OBJECTIVE

Low serum 25-hydroxyvitamin D (25[OH]D) levels have been associated with increased susceptibility to and severity of respiratory viral infections. Hypovitaminosis D may be a modifiable risk factor in the severity of viral respiratory illnesses. The hypothesis for this study was that children hospitalized for respiratory illnesses would have lower serum 25(OH)D levels than controls and that 25(OH)D levels would be associated with illness severity among cases.

METHODS

A case-control study of a sample of patients aged 6 months through 12 years hospitalized from January to May 2010 at an urban pediatric referral hospital was performed. Cases were children hospitalized for acute respiratory illnesses, and controls were children hospitalized for nonrespiratory illnesses. Illness severity among cases was assessed according to hospital length of stay, ICU admission, peripheral oxygen saturation, and pediatric risk of admission II score. Associations between serum 25(OH)D levels and dependent variables were tested for by using binary logistic and multivariable linear regression while controlling for admission diagnosis, age, gender, and race/ethnicity.

RESULTS

The majority of cases (n = 38) and controls (n = 83) were African American (65.8% and 59.0%, respectively). Of the entire cohort (N = 121), 64.8% had vitamin D insufficiency (25[OH]D level ≤30 ng/mL) and 31.1% had vitamin D deficiency (25[OH]D level ≤20 ng/mL). Mean ± SD 25(OH)D levels did not differ between cases and controls (26.8 ± 11.5 vs 26.1 ± 10.6 ng/mL, respectively; P = .73).

CONCLUSIONS

Hypovitaminosis D was common among cases and controls, but it was not significantly associated with the presence or severity of respiratory illnesses.

Adherence to a vitamin D supplement intervention in urban schoolchildren

Vitamin D supplementation is an important strategy for preventing low levels of serum 25OHD and improving bone health and consequent associated health risks, especially in children at risk of deficiency. Although vitamin D supplements are recommended, there is limited research on the factors that influence adherence to taking them. In a cross-sectional sample of 256 child (aged 9 to 15 years) and parent pairs in the Boston, MA, area during January to March 2012, analysis of covariance was used to determine associations between health beliefs about vitamin D, parental vitamin D-containing supplement use, and the individual responsible for pill administration with supplement adherence measured by pill counts. Mean and median supplement pill count adherence over 3 months were 84% and 89%, respectively. Adherence was positively associated with parents' use of vitamin D-containing supplements (7% higher, P=0.008) and with combined child and parent responsibility for administration of the supplement compared with child only (9% higher, P=0.03). Parents' beliefs about vitamin D neither predicted their children's beliefs nor positively influenced children's adherence. Adherence was higher when parents took vitamin D-containing supplements and when parents and children shared responsibility for administering the supplement. Promoting child supplement use through parent involvement and role modeling may be a practical solution for registered dietitians who are aiming to improve vitamin D adherence in at-risk youth.

Vitamin D deficiency is associated with atherosclerosis-promoting risk factor clustering but not vascular damage in children

Background

Vitamin D has been associated with multiple cardiometabolic risk factors in children but there is a paucity of studies examining its correlation to vascular function and structure. Our objective was to determine whether there is a correlation between vitamin D, cardiometabolic risk, vascular distensibility and carotid artery intima-media thickness (CIMT) in high-risk children.

Material/Methods

This was a cross-sectional, cohort study that compared vitamin D to cardiometabolic risk factors, carotid artery distensibility, and CIMT in 74 children with multiple, modifiable atherosclerosis-promoting risk factors. Vitamin D was used as a continuous variable and also categorized as deficient (<20 ng/mL) or sufficient (≥20 ng/mL). Seven modifiable atherosclerosis-promoting risk factors were analyzed – body mass index, systolic blood pressure, total cholesterol, triglyceride, high density lipoprotein cholesterol, fasting insulin, & tobacco smoke exposure history.

Results

For the entire cohort, vitamin D was 26.1±9.4 ng/mL (6–63 ng/mL); and the levels were deficient in 20%. The number of modifiable atherosclerosis promoting risk factors per child was 3.3±1.6. Distensibility index was 2.62±0.87% per 10 mmHg, CIMT 0.54±0.06 mm. There was an inverse correlation between vitamin D and risk factor score (r=−0.27, p=0.02); this remained significant after adjusting for age, sex, and race. There was no association between vitamin D levels and distensibility index or CIMT.

Conclusions

Even though vitamin D levels were inversely correlated with cardiometabolic risk factor score in high-risk children, there are no demonstrable vascular functional or structural effects.

The association between vitamin D and cardiometabolic risk factors in children: a systematic review

The objective of this systematic review was to evaluate the association between serum 25-hydroxyvitamin D (25OHD) and cardiometabolic risk in children and the effect of vitamin D supplementation on risk. We included 35 clinical trials, cross-sectional studies, case-control studies, and cohort studies that evaluated the relationship between 25OHD and blood pressure, lipid levels, insulin/glucose metabolism, endothelial dysfunction, and arterial stiffness. One randomized clinical trial that randomized adolescents to 2000 or 400 IU/d of vitamin D and found improvement in arterial stiffness in the high-dose group and worsening in the low-dose group. One cross-sectional study found no relationship between 25OHD and endothelial dysfunction. Of 12 cross-sectional studies, 10 found an inverse association between 25OHD and systolic blood pressure, although 2 trials found no relationship. There was no consistent association between 25OHD and lipid levels or insulin/glucose metabolism. Insufficient evidence was available to conclude that vitamin D supplementation yields cardiometabolic benefit.

Association between circulating ascorbic acid, α-tocopherol, 25-hydroxyvitamin D, and plasma cytokine concentrations in young adults: a cross-sectional study

BACKGROUND

Inflammation and oxidative stress are associated with the development of numerous chronic diseases. Circulating ascorbic acid, α-tocopherol, and 25-hydroxyvitamin D (25(OH)D) may help reduce concentrations of pro-inflammatory cytokines through their antioxidant and anti-inflammatory properties. These micronutrients may act synergistically, and they may have different anti-inflammatory effects, but previous studies have assessed the link between each of these micronutrients and inflammation in isolation without controlling for the other micronutrients. Our objective was to examine the association between circulating concentrations of ascorbic acid, α-tocopherol, and 25(OH) D and a panel of pro-inflammatory cytokines in an ethnically diverse population of young adults.

METHODS

Participants (n = 1,007) from the Toronto Nutrigenomics and Health study provided fasting blood samples for biomarker measurements and were subsequently categorized into tertiles for each micronutrient based on their circulating concentrations. We conducted Pearson's correlation analyses across all micronutrients and cytokines. The associations between individual micronutrients and cytokines were examined using analysis of covariance with age, sex, waist circumference, ethnicity, physical activity, season of blood collection, total cholesterol, hormonal contraceptive use among women, and the other two micronutrients as covariates.

RESULTS

We observed weak micronutrient-cytokine correlations, moderate correlations between certain cytokines, and strong correlations between specific cytokines, particularly interleukin 1- receptor antagonist (IL-1RA), interferon-γ (IFN-γ), and platelet-derived growth factor BB (PDGF-bb). After full covariate adjustment, circulating α-tocopherol was inversely associated with IFN-γ and regulated upon activation normal T-cell expressed and secreted (RANTES). We observed an unexpected positive association between ascorbic acid and IFN-γ. 25(OH)D was not associated with altered concentrations of any inflammatory biomarkers.

CONCLUSIONS

These findings suggest that α-tocopherol, but not ascorbic acid or 25(OH)D, is inversely associated with inflammation in healthy young adults.

Vitamin D intake and serum vitamin D in ethnically diverse urban schoolchildren

OBJECTIVE

Low serum vitamin D, which largely affects ethnic minorities, is associated with obesity and other chronic diseases. Little is known about racial/ethnic differences in intake, particularly in children, or if any differences are associated with differences in serum 25-hydroxyvitamin D (25(OH)D). The objective of the present study was to determine whether racial/ethnic differences in dietary vitamin D intake exist and whether they explain differences in 25(OH)D.

DESIGN

Vitamin D intakes (Block Kids 2004 FFQ) and 25(OH)D were measured. Race/ethnicity was parent-reported (white (37·9 %), Hispanic (32·4 %), black (8·3 %), Asian (10·3 %), multi-racial/other (11·0 %)). Multivariable analyses were conducted to examine the associations among dietary vitamin D and race/ethnicity, as well as 25(OH)D, independent of BMI Z-score and other covariates.

SETTING

Elementary/middle schools in Somerville, MA, USA, during January-April 2010.

SUBJECTS

Schoolchildren (n 145) in 4th-8th grade.

RESULTS

Only 2·1 % met the 2011 RDA (15 μg/d (600 IU/d)). Average dietary intake was 3.5 (sd 2.2) μg/d (140 (sd 89·0) IU/d). No racial/ethnic differences in intake were evident. Most (83·4 %) were 25(OH)D deficient (<20 ng/ml; 16·0 (sd 6·5) ng/ml). In ANOVA post hoc analyses, 25(OH)D levels were lower in Hispanics than whites (14·6 (sd 6·1) ng/ml v. 17·9 (sd 4·6) ng/ml; P < 0·01). Dietary vitamin D was associated with 25(OH)D overall (P < 0·05), but did not explain the racial/ethnic differences in 25(OH)D.

CONCLUSIONS

Most children in this north-east US sample did not meet dietary recommendations for vitamin D and were vitamin D deficient. Dietary vitamin D did not explain the difference in 25(OH)D between Hispanic and white children. Further research is needed to determine if changes in dietary vitamin D by race/ethnicity can impact 25(OH)D levels.

Optimize dietary intake of vitamin D: an epigenetic perspective

PURPOSE OF REVIEW

Vitamin D has received global attention because of its many health benefits. Although there is general agreement about the importance of vitamin D for bone health, there remains skepticism about the nonskeletal health benefits of vitamin D. This review will not only focus on the vitamin D deficiency pandemic and ways to treat and prevent vitamin D deficiency but will also explore the epigenetic mechanisms of vitamin D that could help explain many of the nonskeletal benefits of enhancing vitamin D status.

RECENT FINDINGS

The Institute of Medicine and the Endocrine Society have made new recommendations for vitamin D intake to prevent vitamin D deficiency. Vitamin D deficiency is defined as a 25-hydroxyvitamin D level below 20 ng/ml and vitamin D insufficiency is defined as 21-29 ng/ml. Recent observations have suggested that vitamin D can influence epigenetics which may help explain the nonskeletal health benefits that have been reported for vitamin D.

SUMMARY

There is general agreement that vitamin D deficiency is a worldwide health problem. This is due in part to the lack of appreciation that sunlight is an important source of vitamin D. There is no downside to increasing vitamin D intake and recent observations suggesting that vitamin D influences epigenetics provide a new insight for the importance of vitamin D in utero in reducing risk of chronic diseases later in life.

Vitamin D status is linked to biomarkers of oxidative stress, inflammation, and endothelial activation in obese children

OBJECTIVE

To examine vitamin D, parathyroid hormone, and serum calcium-phosphorus levels relationships to biomarkers of oxidative/nitrosative stress, inflammation, and endothelial activation, potential contributors for vascular complications in obese children.

STUDY DESIGN

Cross-sectional clinical study of 66 obese Caucasian children aged 7 to 14 years. Cardiovascular risk factors were assessed. Malondialdehyde and myeloperoxidase as measures of oxidative stress, and plasma nitrite+nitrate, urinary nitrate, and 3-nitrotyrosine as markers of nitrosative stress were measured. Adipocytokines, inflammatory molecules (high-sensitivity C-reactive protein, interleukin-6, and tumor necrosis factor-α), endothelial activation molecules (soluble intercellular adhesion molecule-1, soluble vascular cell adhesion molecule 1 [sVCAM-1]), E-selectin, and vascular endothelial growth factor were also investigated. Serum 25-hydroxy-cholecalciferol [25(OH)D], intact parathormone, and calcium-phosphorus levels were determined in these children and in a comparison group of 39 non-obese children.

RESULTS

Obese children had a significantly lower 25(OH)D level (P = .002) and a higher intact parathormone (P = .011) than non-obese children. Phosphorus and the calcium-phosphorus product were also significantly higher (P < .0001). Insufficient serum concentrations of 25(OH)D (<20 ng/mL) were detected in 5% of normal children and in 30% of the obese children. In the obese children with vitamin D insufficiency, malondialdehyde, myeloperoxidase, 3-nitrotyrosine, interleukin-6, and sVCAM-1 were substantially elevated. A partial correlation analysis showed an inverse relationship of 25(OH)D levels with 3-nitrotyrosine (r = -0.424, P = .001), and sVCAM-1 (r = -0.272, P = .032).

CONCLUSIONS

Insufficient 25(OH)D levels were detected in severely obese children with increased markers of oxidative/nitrosative stress, inflammation, and endothelial activation.