Low vitamin D is associated with hypertension in paediatric obesity

Calcium, Phosphate, and Vitamin D in Children and Adolescents with Chronic Diseases: A Cross-Sectional Study

Chronic diseases may affect the nutritional status of children and adolescents. Calcium (Ca), phosphorus (P), and vitamin D (Vit-D) are crucial nutrients for their growth and development. Proper diagnosis and treatment are critical components of personalized and precision medicine. Hence, we conducted a cross-sectional and comparative study to evaluate Ca, P, and Vit-D levels in their non-skeletal functions and their association with health and nutritional biomarkers in children and adolescents with diverse chronic conditions. We performed anthropometric, body composition, clinical evaluation, biochemical analysis, and dietary survey methods. A total of 78 patients (1-19 years, 43 females, 42 children) took part in this study. Overall, 24, 30, and 24 participants were obese, undernourished, and eutrophic, respectively. Results found that 74% and 35% of individuals had deficient Vit-D and Ca intake, respectively. Most cases were normocalcemic. Results also found that 47% of the subjects had Vit-D deficiency (VDD), 37% were insufficient, and 37% had hypophosphatemia. Of the 46% and 31% of patients with VDD and insufficient levels, 19% and 11% were hypophosphatemic, respectively. Calcium, P, and Vit-D levels were associated with anthropometric parameters, body mass index, body composition, physical activity, diet, growth hormones, and the immune, liver, and kidney systems. These results show the coincident risk of altered Ca, P, and Vit-D metabolism in children and adolescents with chronic diseases.

Vitamin D deficiency and cardiometabolic risk factors in adolescents: systematic review and meta-analysis

Vitamin D deficiency is associated with an increase in the occurrence of cardiometabolic events, but the evidence of this relationship in adolescence is still limited. Thus, we analyzed the association between vitamin D deficiency and cardiometabolic risk factors in adolescents. Observational studies were searching in PubMed/Medline, Embase, Scopus, Web of Science, Science Direct, Lilacs, and Google Scholar database. Random effects models were used to summarize standardized mean differences for as a summary measure. The certainty of the evidence was verified using the Cochrane recommendations. A total of 7537 studies were identified, of which 32 were included in the systematic review and 24 in the meta-analysis.Vitamin D deficiency was associated with increased systolic pressure (SMD = 0.22; 95%CI = 0.10; 0.34), diastolic pressure (SMD = 0.23; 95%CI = 0.10; 0.35), glycemia (SMD = 0.13; 95%CI = 0.05; 0.12), and insulin (SMD = 0.50; 95%CI = 0.15; 0.84), an increase in the HOMA index (SMD = 0.48; 95%CI = 0.36; 0.60), high triglyceride values (SMD = 0.30; 95%CI = 0.11; 0.49), and reduced HDL concentrations (SMD= -0.25; 95%CI = -0.46; -0.04). No statistically significant association was observed for glycated hemoglobin, LDL cholesterol, and total cholesterol. Most of the studies presented low and moderate risks of bias, respectively. The certainty of the evidence was very low for all the outcomes analyzed. Vitamin D deficiency was associated with increased exposure to the factors linked to the occurrence of cardiometabolic diseases in adolescents. Systematic Review Registration: PROSPERO (record number 42,018,086,298).

A comprehensive look into the association of vitamin D levels and vitamin D receptor gene polymorphism with obesity in children

Childhood obesity accounts for several psychosocial and clinical consequences. Psychosocial consequences include lower self-esteem, social isolation, poor academic achievement, peer problems, and depression, whereas clinical consequences are cardiovascular diseases, type 2 diabetes, dyslipidemia, cancer, autoimmune diseases, girls early polycystic ovarian syndrome (PCOS), asthma, bone deformities, etc. A growing number of studies have uncovered the association of childhood obesity and its consequences with vitamin-D (vit-D) deficiency and vitamin-D receptor (VDR) gene polymorphisms such as single nucleotide polymorphisms (SNPs), e.g., TaqI, BsmI, ApaI, FokI, and Cdx2. Considering the impact of vit-D deficiency and VDR gene polymorphisms, identifying associated factors and risk groups linked to lower serum vit-D levels and prevention of obesity-related syndromes in children is of utmost importance. Previously published review articles mainly focused on the association of vit-D deficiency with obesity or other non-communicable diseases in children. The nature of the correlation between vit-D deficiency and VDR gene polymorphisms with obesity in children is yet to be clarified. Therefore, this review attempts to delineate the association of obesity with these two factors by identifying the molecular mechanism of the relationship.

Hypertension in obese children is associated with vitamin D deficiency and serotonin dysregulation

Background

Obesity and hypertension represent serious health issues affecting the pediatric population with increasing prevalence. Hypovitaminosis D has been suggested to be associated with arterial hypertension. Serotonin by modulating nitric oxide synthase affect blood pressure regulation. The biological mechanism by which vitamin D specifically regulates serotonin synthesis was recently described. The aim of this paper is to determine the associations between vitamin D, serotonin, and blood pressure in obese children.

Methods

One hundred and seventy-one children were enrolled in the prospective cross-sectional study. Two groups of children divided according to body mass index status to obese (BMI ≥95th percentile; n = 120) and non-obese (n = 51) were set. All children underwent office and ambulatory blood pressure monitoring and biochemical analysis of vitamin D and serotonin. Data on fasting glucose, insulin, HOMA, uric acid, and complete lipid profile were obtained in obese children.

Results

Hypertension was found only in the group of obese children. Compared to the control group, obese children had lower vitamin D and serotonin, especially in winter. The vitamin D seasonality and BMI-SDS were shown as the most significant predictors of systolic blood pressure changes, while diastolic blood pressure was predicted mostly by insulin and serotonin. The presence of hypertension and high-normal blood pressure in obese children was most significantly affected by vitamin D deficiency and increased BMI-SDS.

Conclusions

Dysregulation of vitamin D and serotonin can pose a risk of the onset and development of hypertension in obese children; therefore, their optimization together with reducing body weight may improve the long-term cardiovascular health of these children.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-022-03337-8.

Serum 25-Hydroxyvitamin D correlates with systolic blood pressure in obese male schoolchildren

INTRODUCTION

Childhood obesity is associated with an increased risk of chronic diseases. We aimed to examine the relation between serum levels of 25-hydroxyvitamin D (25[OH]D) and blood pressure in obese schoolchildren.

MATERIAL AND METHODS

Cross-sectional study in school-age children with obesity. The serum levels of 25(OH)D were measured and classified as sufficient or insufficient/deficient. Blood pressure was measured. Normal values were considered <90th percentile, elevated blood pressure ≥90th to <95th percentiles, and hypertension ≥95th percentile, according to blood pressure reference tables, specific for age, sex, and height. The Pearson correlation was performed.

RESULTS

256 obese schoolchildren (123 [48.0%] females and 133 [51.9 %] males) were evaluated. The prevalence rates of vitamin D deficiency, insufficiency, and sufficiency were 23.4%, 52.3%, and 24.2%, respectively. Normal blood pressure was observed in 101 (39.4%) children; the frequencies of elevated blood pressure and hypertension were 10.9% and 49.6%, respectively. A moderate inverse correlation of 25(OH) D levels with systolic blood pressure levels (r = -0.54, p = 0.03) was observed. When analyzed by sex, a significantly high inverse correlation between 25(OH)D levels and systolic blood pressure was observed in males (r=-0.85 and p=<0.001). No significant correlation was found in females (systolic r=-0.16 and p=0.67; diastolic r= -0.15 and p=0.812). When performing the multiple regression analysis, the 25(OH)D levels and body mass index (BMI) were the significant predictors for systolic blood pressure.

CONCLUSIONS

We identified an inverse correlation between 25[OH]D levels and systolic blood pressure in male schoolchildren with obesity.

The role of serum 25 (OH) vitamin D level in the correlation between lipid profile, body mass index (BMI), and blood pressure

BACKGROUND AND AIMS

Since the prevalence of vitamin D deficiency is high in some countries, such as Iran, and the trend of hypertension and obesity is increasing, this study aimed to investigate the serum level of vitamin D and explore its correlation and association with obesity, blood pressure, fasting blood sugar (FBS), and lipid profile. Our hypothesis is that serum vitamin D levels are associated with risk factors for cardiometabolic disease such as hypertension.

METHODS

The results of this article were extracted from a cross-sectional study with a sample size of 720 people in the winter of 2020. The serum level of 25 OH vit D was measured using the ELISA method. In addition, lipid profiles were measured using the Auto Analyzer photometry method.

RESULTS

Serum levels of vitamin D (25 (OH) vitamin D) were significantly higher in the control group compared to the case group (29.5 ± 16.3 vs. 26.7 ± 14.5; P-value = 0.016). The significant association between body mass index (BMI) and FBS (Beta unadjusted:0.024, 95%CI 0.009:0.038; Beta adjusted:0.020,95%CI 0.005:0.034), and triglyceride (Beta unadjusted:0.009, 95%CI 0.006:0.012; Beta adjusted:0.008,95%CI 0.005:0.011), and an inverse association HDL-C (Beta unadjusted:-0.079,95%CI -0.123:-0.036; Beta adjusted:-0.065,95%CI -0.111:-0.019) were seen in both unadjusted and adjusted models.

CONCLUSION

In conclusion, we report that obese people had significantly lower serum vitamin D levels than normal-weight people. There is also a significant correlation between BMI and blood pressure.

Vitamin D in pediatric patients with obesity and arterial hypertension

The purpose of this study was to find potential differences in vitamin D levels between different groups: overweight children with hypertension, normal-weight children with hypertension, overweight children with normal blood pressure and normal-weight children without hypertension, representing the control group. We also wanted to determine whether there are correlations between vitamin D levels and other clinical laboratory parameters, to evaluate the potential need for substitution. We measured vitamin D, homocysteine, total cholesterol, HDL, LDL, triglycerides, uric acid, glucose, apolipoprotein A1, apolipoprotein B, alkaline phosphatase, calcium, phosphate and magnesium serum levels in all groups. We also took anthropometric measurements (body weight, height, body mass index (BMI)) and observed patients' blood pressure. The results were analyzed with SPSS statistic tool with basic statistical methods. The study included 175 children between 5 and 18 years of age. Fiftyseven were healthy (group A-control group), 41 normal-weight with hypertension (group B), 44 overweight with hypertension (group C) and 33 overweight with normal blood pressure (group D). The results showed statistically significant differences in values of vitamin D between all groups-A and B (p = 0.003), A and C (p < 0.001), A and D (p < 0.001), B and D (p = 0.043), B and C (0.030), except for groups C and D (p = 0.830). There were statistically significant correlations between vitamin D and BMI (r = - 0.196, p = 0.010), systolic pressure (r = - 0.190, p = 0.002), diastolic pressure (r = - 0.149, p = 0.050), homocysteine (r = - 0.208, p = 0.007), triglycerides (r = - 0.196, p = 0.011) and apolipoprotein A1 (r = 0.222, p = 0.007), confirmed in multivariate model. For the blood pressure, the higher the systolic blood pressure, the lower the average vitamin D was. The pilot study shows significant differences in serum vitamin D levels between all groups of children, apart from groups C and D. These results, combined with statistically significant correlations between vitamin D and systolic and diastolic blood pressure suggest the need for monitoring and potential substitution of vitamin D in in pediatric patients with hypertension.

Vitamin D status and blood pressure in children and adolescents: a systematic review of observational studies

BACKGROUND

Childhood hypertension is a growing public health problem. Simultaneously, hypovitaminosis D is widespread in this population and could be associated with hypertension. This study systematically reviewed the literature on the relationship between vitamin D status and blood pressure (BP) in children and adolescents.

METHODS

Following the PRISMA guidelines, PUBMED, MEDLINE, CINAHL, EMBASE, Cochrane Library, and ClinicalTrials.gov and the gray literature without language or time restrictions were searched. We included observational studies, assessed their risk of bias, and extracted data on population characteristics, vitamin D status and BP measurements, and the association between the two variables. A narrative analysis of the studies was performed.

RESULTS

In total, 85 studies were included. Prospective cohort studies showed no association between vitamin D and BP, and generally, they were flawed. Also, the majority of non-prospective cohort studies (cross-sectional, retrospective, case-control) did not report an association between vitamin D and BP. They were mostly flawed regarding BP measurement and adjusting to potential confounders.

CONCLUSION

The results on the relationship between vitamin D status and BP in children and adolescents varied between the studies, and mainly pointed towards lack of association.

Vitamin D effects and endocrine diseases

A lack of vitamin D has been linked to autoimmune diseases including type 1 diabetes, autoimmune thyroiditis and to obesity. The prevalence of vitamin D deficiency is higher in diabetic or obese children and patients with thyroiditis compared to healthy controls. Moreover, low vitamin D values seem to be associated with major complications and poor glycemic control, in particular in obese children. Supplementation with vitamin D, which has immune-regulatory properties, may support our therapies and improve the outcomes in different diseases. Although some studies suggest a possible role of vitamin D in the etiology of autoimmune diseases and obesity, data on supplementation benefits are inconclusive and further studies are needed. In this paper, we focus on the current evidence regarding vitamin D function in endocrine diseases and possible benefits of its supplementation in pediatric age.

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.

Vitamin D and Cardiovascular Risk: which Implications in Children?

Vitamin D (25OHD) pleiotropic effects are widely recognized and studied. Recently, vitamin D cardiovascular effects are gaining interest, especially in children, although the studies present conflicting data. Some randomized controlled trials (RCTs) have demonstrated that cardiovascular risk markers, such as lipid parameters, inflammation markers, blood pressure, and arterial stiffness, are unaffected by vitamin D supplementation. By contrast, other studies show that low vitamin D levels are associated with higher risk of cardiovascular disease (CVD) and mortality, and support that increased risk of these diseases occurs primarily in people with vitamin D deficiency. An update on these points in pediatric patients is certainly of interest to focus on possible benefits of its supplementation.

Vitamin D Supplementation and Blood Pressure in Children and Adolescents: A Systematic Review and Meta-Analysis

Suboptimal vitamin D status is associated with elevated blood pressure (BP) in children and adolescents. Whether vitamin D supplementation reduces BP remains unclear. To systematically review whether vitamin D supplementation reduces BP in children and adolescents, we conducted a literature review according to the PRISMA statement. We included vitamin-D supplementation human interventions studies that reported on BP as an outcome. We searched PUBMED, MEDLINE, CINAHL, EMBASE, the Cochrane Library, and the clinical trials website. We also hand searched the references of the included articles and previous reviews of vitamin D therapy. No language or time restrictions were applied. We extracted data on population characteristics, baseline and endline vitamin D and BP values, and assessed the risk of bias of the included studies. We performed a narrative review of the findings, conducted a meta-analysis when possible, and performed sensitivity analyses to test the robustness of our results. We assessed the overall quality of the evidence produced in the meta-analysis. We included eight studies in our review and five studies in the meta-analysis, none of which included hypertensive only participants. The risk of bias was variable. In non-randomized studies, no effect of vitamin D supplementation was seen on systolic BP (SBP) (mean difference: 0.39 (95% confidence interval (CI): −0.9; 1.68) mmHg; p = 0.55; I² = 0%). Only a significant decrease in diastolic BP (DBP) (mean difference: −1.87 (95% CI: −3.02; −0.72) mmHg; p = 0.001; I² = 0%) was noted. Both analyses had a low quality of evidence. In randomized controlled trials (RCTs), no effect was noted on SBP (mean difference: −2.04 (95% CI: −5.12; 1.04) mmHg; p = 0.19; I² = 71%) nor DBP (mean difference: 0.01 (95% CI: −1.09; 1.12) mmHg; p = 0.98; I² = 0%). The final quality of evidence ranged between low and moderate. Sensitivity analyses did not affect the results. Vitamin D supplementation was found to be ineffective in lowering SBP and DBP in children and adolescents.

Effect of vitamin D3 supplementation on vascular and metabolic health of vitamin D-deficient overweight and obese children: a randomized clinical trial

BACKGROUND

Obese children are vulnerable to vitamin D deficiency and impaired cardiovascular health; vitamin D replenishment might improve their cardiovascular health.

OBJECTIVES

The aims were to determine, in vitamin D-deficient overweight and obese children, whether supplementation with vitamin D3 1000 or 2000 IU/d is more effective than 600 IU/d in improving arterial endothelial function, arterial stiffness, central and systemic blood pressure (BP), insulin sensitivity (1/fasting insulin concentration), fasting glucose concentration, and lipid profile and to explore whether downregulation of adipocytokines and markers of systemic inflammation underlies vitamin D effects.

METHODS

We conducted a randomized, double-masked, controlled clinical trial in 225 10- to 18-y-old eligible children. Change in endothelial function at 6 mo was the primary outcome.

RESULTS

Dose-response increases in serum 25-hydroxyvitamin D concentrations were significant and tolerated without developing hypercalcemia. Changes at 3 and 6 mo in endothelial function, arterial stiffness, systemic-systolic BP, lipids, and inflammatory markers did not differ between children receiving 1000 or 2000 IU vitamin D and children receiving 600 IU. Some secondary outcomes differed between groups. Compared with the 600-IU group, central-systolic, central-diastolic, and systemic-diastolic BP was lower at 6 mo in the 1000-IU group [-2.66 (95% CI: -5.27, -0.046), -3.57 (-5.97, -1.17), and -3.28 (-5.55, -1.00) mm Hg, respectively]; insulin sensitivity increased at 3 and 6 mo and fasting glucose concentration declined at 6 mo (-2.67; 95% CI: -4.88, -0.46 mg/dL) in the 2000-IU group.

CONCLUSIONS

Correction of vitamin D deficiency in overweight and obese children by vitamin D3 supplementation with 1000 or 2000 IU/d versus 600 IU/d did not affect measures of arterial endothelial function or stiffness, systemic inflammation, or lipid profile, but resulted in reductions in BP and fasting glucose concentration and in improvements in insulin sensitivity. Optimization of children's vitamin D status may improve their cardiovascular health. This trial was registered at clinicaltrials.gov as NCT01797302.

The Association of Vitamin A and Vitamin D with Hypertension in Children: A Case-Control Study

BACKGROUND

The prevalence of hypertension in children increases rapidly. This paper is to investigate the association of vitamin A and serum 25(OH)D level with hypertension and to explore the risk factors of hypertension in children.

METHODS

164 children (age: 6-12 years, females: 49.39%) were included in this case-control study. The serum vitamin A and serum 25(OH)D level, the transcription level of RARs and RXRs, 25(OH)D receptor, and the retinol acyltransferase (LRAT), an indicator of vitamin A storage function, were measured.

RESULTS

The serum vitamin A level in hypertensive subjects was not significantly different compared to control, but the serum 25(OH)D level was significantly lower in hypertensive subjects compared to control (38.22±12.00umol/L vs. 43.28±12.33 umol/L, P=0.02). The transcription levels of RARα, RARβ, and RARγ were not significantly different between the two groups; but the LRAT was lower in the hypertensive group than that in the control (P<0.001). Compared with control group, the level of 25(OH)D receptor was lower in hypertension children (P=0.003). Logistic regression model showed that LRAT, HDL, and breastfed duration were negatively associated with blood pressure, and waist circumference was positively associated with blood pressure.

CONCLUSIONS

The LRAT, serum 25(OH)D, and 25(OH)D receptor were significantly associated with blood pressure level, and both breastfed and HDL-C were independent protective factors of blood pressure level in children.

Fetuin B links vitamin D deficiency and pediatric obesity: Direct negative regulation by vitamin D

Vitamin D (VD) deficiency (VDD) correlates to obesity, with VD a recognized mediator of metabolic diseases. From a previous proteomic study identifying adiponectin as a link between VDD and pediatric obesity, herein we analysed another protein (SSP2301) increased with VDD. A focused 2D-electrophoretic analysis identified 4 corresponding plasma proteins, with one predicted to be fetuin B (FETUB). FETUB was studied due to its emerging role in metabolic diseases and cytogenetic location (3q27.3) with adiponectin. Results were confirmed in obese children, where plasma FETUB was higher with VDD. A direct effect by 1α,25-(OH)2D3 on hepatocellular FETUB synthesis was observed, with a time and dose dependent reduction. Further, we demonstrated the VD-receptor (VDR) is key, with FETUB "released" with VDR silencing. Finally, VD supplementation (6weeks) to juvenile mice fed a standard diet, reduced plasma FETUB. Only at 22weeks did liver FETUB correspond to plasma FETUB, highlighting the contribution of other VD-responsive tissues. Overall, FETUB is a key protein linking VDD to pediatric obesity. With an emerging role in metabolic diseases, we demonstrate that VD/VDR directly regulate FETUB.

Associations between 25-hydroxyvitamin D levels, body composition and metabolic profiles in young women

BACKGROUND/OBJECTIVES

Cardiovascular disease (CVD) is a major cause of mortality and morbidity globally. Results from previous studies are inconsistent and it remains unclear whether low-serum 25 OHD levels are associated with an increased risk of CVD. These associations have been little studied in young women. The aim of this study was to assess the relationship between serum 25 OHD and obesity, body composition, metabolic profiles and blood pressure in young women.

SUBJECTS/METHODS

Women aged 16-25 years living in Victoria, Australia, were recruited through Facebook advertising in this cross-sectional study. Participants completed an online survey and attended a site visit in a fasted state, where parameters, including blood pressure, anthropometry, metabolic profiles, serum 25 OHD levels and body composition (using dual energy X-ray absorptiometry) were measured.

RESULTS

A total of 557 participants were recruited into this study. Multiple linear regression analysis showed that after adjusting for visceral fat, season, smoking, physical activity, age, alcohol intake, oral contraceptive use, country of birth, taking multivitamins and taking vitamin D supplement, a 10 nmol/L increase in 25 OHD levels was associated with 0.65% greater HDL levels (p = 0.016) and 0.92% greater triglyceride levels (p = 0.003). It was also associated with 0.48% lower BMI (p < 0.001), 0.50% lower total fat percentage (p < 0.001), 0.09% lower visceral fat percentage (p < 0.001), 0.14% lower visceral fat to total fat ratio (p < 0.001) and 0.36% lower trunk fat to total fat ratio (p < 0.001), after adjustment for season, smoking, physical activity, age, alcohol intake, oral contraceptive use, country of birth, taking multivitamins and taking vitamin D supplements. Although these associations were statistically significant, they were very small in magnitude and of uncertain clinical significance.

CONCLUSIONS

These findings may help to explain an association between 25 OHD levels and CVD risk factors through associations with HDL, BMI, total body and visceral fat mass. Possible underlying mechanisms warrant further investigation.

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 Status, Cardiometabolic, Liver, and Mental Health Status in Obese Youth Attending a Pediatric Weight Management Center

BACKGROUND

Vitamin D (VitD) deficiency and obesity are reaching epidemic proportions in North America, particularly in those with comorbid conditions such as diabetes or liver disease. The study objective was to determine the prevalence of suboptimal vitD status and interrelationships with anthropometric, cardiometabolic, liver, mental health, and lifestyle (sleep/screen time) parameters in an ambulatory population of children with obesity.

METHODS

Children (2-18 years) attending a pediatric weight management clinic (n = 217) were retrospectively reviewed. Variables studied included anthropometric (weight, height, body mass index, waist circumference), vitD (serum 25-hydroxyvitamin D), cardiometabolic (systolic blood pressure, diastolic blood pressure, glucose, insulin, homeostasis model assessment for insulin resistance, triglyceride, high-density lipoprotein, low-density lipoprotein, total cholesterol), liver enzymes (alanine aminotransferase, gamma-glutamyl transferase), and mental health (number, diagnosis) parameters.

RESULTS

Suboptimal vitD status (25-hydroxyvitamin D <75 nmol/L was present in 76% of children with obesity (12.0 ± 2.9 years). Blood pressure categorized as prehypertension, stage I hypertension, and stage II hypertension was present in 14%, 25%, and 7% of children, respectively. Mental health diagnoses including anxiety, attention-deficit hyperactivity disorder, mood disorders, and learning disabilities/developmental delays occurred in 18%, 17%, 10%, and 15%, of children, respectively. Waist circumferences >100 cm were associated with lower vitD levels (58 ± 18 vs 65 ± 17 nmol/L; P = 0.01). VitD status ≥50 nmol/L was associated with lower insulin (15.8 [11.7-23.1] mU/L vs 21.1 [14.3-34.2] mU/L; P < 0.01) and homeostasis model assessment for insulin resistance (3.5 [2.5-4.9] vs 4.8 [3.1-6.9]; P < 0.01) values and systolic blood pressure percentiles (73.0 ± 25.8 vs 80.6 ± 17.0; P = 0.04).

CONCLUSIONS

Children with obesity had a high prevalence of vitD deficiency, particularly those at risk for hypertension, reduced insulin sensitivity, and central obesity.

The association of adiposity, physical fitness, vitamin D levels and haemodynamic parameters in young Saudi females

Objectives

In this study, we assessed the possible association of adiposity, physical fitness, vitamin D levels and haemodynamic parameters as intermediate risk factors for cardiovascular health in young Saudi women.

Methods

A total of 87 young healthy Saudi women were recruited in this cross-sectional study during 2014–2015. The body weight, height, waist and hip circumference, and plasma 25-hydroxyvitamin D (25[OH] D) levels were measured. The exercise stress test was performed to determine the pulse rate, blood pressure (BP), ECG, and VO_2max. Multiple linear regression models were generated for the resting (r) and maximum (m) diastolic (D) and systolic (s) arterial BP and pulse rate (PR), adiposity markers, VO_2max, and plasma levels of 25(OH) D.

Results

A multiple linear regression model was significant for the rDBP, mDBP, rSBP, and mSBP with adjusted R² (6.5, 10.2, 8.3, and 4.5%, respectively). Except for VO_2max in the mDBP model, none of the included risk factors were significant according to the t-test.

Conclusion

This study showed the association of high adiposity and decreased physical fitness with haemodynamic parameters in young Saudi women. An exaggerated exercise DBP might predict future cardiovascular risk in unfit young women.

Elevated systolic blood pressure of children in the United States is associated with low serum 25-hydroxyvitamin D concentrations related to body mass index: National Health and Examination Survey 2007-2010

A negative association between serum 25-hydroxyvitamn D (25[OH]D) concentrations and blood pressure has been found in adults; whether a similar relationship exists in children remains unclear. We hypothesized that serum 25(OH)D concentrations of children would negatively correlate with blood pressure. Using a nationally representative sample of children aged 8 to 18years from the National Health and Nutrition Examination Survey 2007-2010 (n=2908), we compared serum 25(OH)D levels with diastolic and systolic blood pressure by vitamin D nutritional status categories. A high percentage of children were either vitamin D deficient (28.8%) or vitamin D insufficient (48.8%). Prehypertension was defined as blood pressure as ≥90th to <95th percentile and hypertension as ≥95th percentile by age, height, and sex national blood pressure percentile norms for children. Vitamin D-deficient children aged 8 to 13years had higher systolic blood pressure (104.8±0.7mm Hg) than did vitamin D-sufficient children (102.3±0.6mmHg; P<.05). Controlling for age, sex, race/ethnicity, and income, systolic blood pressure was inversely associated with serum 25(OH)D concentrations (P<.03), but not when also controlling for body mass index (P=.63). A higher percentage of vitamin D-deficient and vitamin D-insufficient children (1.7%) vs vitamin D-sufficient children (0.6%) had prehypertension or hypertension. In conclusion, the association of low serum 25(OH)D concentrations with elevated systolic blood pressure in children is likely related to body weight and markers of adiposity.

Predictors of Serum 25-Hydroxyvitamin D Concentrations among a Sample of Egyptian Schoolchildren

Objective. To assess the level of 25-hydroxyvitamin D status among a sample of Egyptian schoolchildren and to evaluate predictors of deficiency and insufficiency. Subjects and Methods. A cross-sectional study comprising 200 prepubescent schoolchildren aged from 9 to 11 years was performed. A questionnaire including frequency of midday sun exposure, milk intake, physical activity, and level of maternal education was taken. Body mass index (BMI) was calculated; serum 25-hydroxyvitamin D [25(OH)D], serum calcium, phosphorus, and parathyroid hormone were measured. Results. Vitamin D deficiency [serum 25(OH)D < 20 ng/mL] was detected in 11.5% of subjects while its insufficiency (serum 25(OH)D is between 20 and 29.9 ng/mL) was detected in 15%. Results revealed that obesity, low physical activity, low sun exposure, and low maternal education level are significant predictors of insufficiency, though female gender, low maternal education level, and low milk intake are significant predictors of deficiency. Lower serum phosphorus and higher serum parathyroid hormone were significantly associated with both deficiency and insufficiency (p < 0.05). Conclusion. Vitamin D deficiency and insufficiency are common among schoolchildren in Egypt. Food fortification, vitamin D supplementation, and increasing maternal awareness about the importance of physical activity and exposure of their children to ultraviolet light may help to overcome this problem.

Risk factors of vitamin D deficiency in children with epilepsy taking anticonvulsants at initial and during follow-up

PURPOSE

Vitamin D status was evaluated in children with epilepsy taking anticonvulsants to determine the prevalence and risk factors of vitamin D deficiency.

METHODS

This study was designed as both a cross-sectional and a retrospective cohort study. A sum of 198 children who were diagnosed with epilepsy at the Department of Pediatrics in Dankook University Hospital was included. Their serum vitamin D levels were reviewed based on clinical information, and analyzed using IBM SPSS ver. 20.0.

RESULTS

One hundred twenty-four children (62.6%) had vitamin D deficiency. Two risk factors were associated: winter to spring season (odds ratio [OR], 3.71; 95% confidence interval [CI], 1.835-7.492) and age more than 12 years (OR, 3.22; 95% CI, 1.377-7.542). Out of the 57 patients who were not vitamin D deficient at the time of initial assay, 47 patients (82.5%) became vitamin D deficient during followup. The change of serum 25-hydroxy vitamin D3 (25(OH)D) levels during follow up showed a weak negative correlation with the duration of medication (r=-0.283, P=0.033). Medication duration was longer and brain magnetic resonance imaging (MRI) abnormality, abnormal underlying conditions, and nonambulatory status were more frequently present in twenty-five patients (44%) who showed a decline of more than 15 ng/mL during follow-up (P<0.05).

CONCLUSION

Vitamin D deficiency is common in children with epilepsy taking anticonvulsants, especially in adolescents more than 12 years of age. This study emphasizes the regular monitoring of vitamin D level, especially in the presence of longer duration of medication, brain MRI abnormality, abnormal underlying conditions, and nonambulatory status.

Does vitamin D status track through adolescence?

BACKGROUND

To our knowledge, no studies have reported on the long-term variability of vitamin D status in adolescents.

OBJECTIVE

To determine whether tracking of vitamin D status occurs in healthy adolescents, we assessed the variability of 25-hydroxyvitamin D [25(OH)D] every 2 y over a 10-y period in a longitudinal cohort of adolescents living in Johannesburg, South Africa (latitude 26°S).

DESIGN

Healthy adolescents who had blood samples available on ≥3 occasions between 11 and 20 y of age were included in the study. Of the cohort of 504 children, 99 met the criteria. The mean 25(OH)D concentration at each time point was measured, and the individual 25(OH)D z scores based on year 11 values were used as the reference. All 25(OH)D concentrations for a subject were measured in a single assay.

RESULTS

No significant correlation was found between 25(OH)D in the earlier and later years of adolescence, although significant correlations were found between year 11 and year 13 (r = 0.71, P < 0.0001) and between years 15, 17, and 20 (r ≥ 0.65, P < 0.0001). The percentage of adolescents whose 25(OH)D concentration changed by >20 nmol/L from year 11 was calculated for all age groups: 12% of the cohort had a change of >20 nmol/L at 13 y of age compared with 46% at 20 y of age. Just more than one-half (53%) of the cohort changed their category of vitamin D status between the ages of 11 and 20 y, and one-third of adolescents changed from being replete to insufficient over the same period.

CONCLUSIONS

The data suggest that the measurement of 25(OH)D at a single time point does not reflect the long-term vitamin D status of an adolescent. These findings may cast doubt on the veracity of those studies that suggest an association of vitamin D status with various disease states in which vitamin D status was measured only once.