Serum 25-hydroxyvitamin D concentrations in girls aged 4-8 y living in the southeastern United States

The Impact of Whole Egg Consumption on Bone Accrual in Healthy Children: A Randomized Controlled Trial

Dietary interventions designed to examine the role of nutrition on childhood bone accrual have often focused on the role of individual micronutrients (eg, calcium, vitamin D, and zinc) and macronutrients (eg, protein). The osteogenic benefits of whole foods, such as eggs, are not well understood despite eggs being a source of high-quality nutrients and bioactive compounds known to positively influence bone. A significant positive cross-sectional association between whole egg consumption and tibia cortical bone mass has recently been shown in young children; however, randomized controlled trials (RCTs) have not been conducted. This study is a double-blind RCT in male and female children ages 9-13 years of different ancestries, designed to determine if consuming food products with whole eggs (equivalent to 8-10 eggs/wk) versus foods with milk or gelatin (placebo) over a 9-month period will improve measures of bone strength. Total body less head (TBLH) and lumbar spine bone mineral content (BMC) and areal bone mineral density (aBMD) were assessed using dual-energy X-ray absorptiometry (DXA). DXA Z-scores were computed using published pediatric growth charts and were adjusted for height-for-age Z-score (HAZ). Mid-tibia cortical volumetric BMD, BMC, cortical area, total bone area, cortical thickness, and strength strain index were measured using peripheral quantitative computed tomography. Overall, there were no significant intervention effects for any bone outcomes. The increase in spine BMCHAZ Z-score in the egg group versus the gelatin group approached significance (p = 0.07). Significant time effects in TBLH aBMDHAZ Z-score occurred as all groups decreased over 9 months (p < 0.03). Most tibia cortical bone outcomes increased over time (all p < 0.02), but changes did not differ across intervention groups. Whole eggs provide important nutritional benefits for children, but the bone responses to consumption of 8-10 eggs/wk over a period of 9 months in children entering the early stages of puberty were small. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Vitamin D status of 3-year-old children in Denmark: determinants and associations with bone mineralisation and blood lipids

PURPOSE

Low vitamin D status is a global problem and has been associated with reduced skeletal and cardiometabolic health. However, evidence in young children is lacking. We, therefore, aimed to characterise vitamin D status in toddlers, identify its determinants, and explore if vitamin D status was associated with bone mineralisation and lipid profile.

METHODS

We used cross-sectional data from 3-year-old children (n = 323) living in Denmark (latitude: 55°N). Bone mineralisation (n = 108) was measured by DXA. Blood samples were analysed for serum 25-hydroxyvitamin D (s-25(OH)D) by LC-MS/MS, triacylglycerol, and total, low- and high density lipoprotein cholesterol.

RESULTS

Mean ± SD s-25(OH)D was 69 ± 23 nmol/L, but varied with season. During winter, 38% had inadequate s-25(OH)D (< 50 nmol), whereof 15% had deficiency (< 30 nmol/L); these numbers were only 7 and 1% during summer. In terms of status determinants, supplement use (66% were users) was associated with s-25(OH)D (P < 0.001), whereas dietary vitamin D intake (median [25-75^th percentile] of 1.3 [0.9-1.9] µg/d), sex, parental education, BMI, and physical activity were not. There were no associations between s-25(OH)D and blood lipids or bone measurements, using either unadjusted or adjusted regression models.

CONCLUSION

More than 1/3 of Danish toddlers had inadequate vitamin D intake during winter, but acceptable mean vitamin D status. In addition to season, supplement use was the main determinant of vitamin D status, which was, however, not associated with bone mineralisation or lipid profile. The results support recommendations of vitamin D supplements during winter at northern latitudes, but potential health effects need further investigation.

High-dose vitamin D supplementation in pregnancy and 25(OH)D sufficiency in childhood reduce the risk of fractures and improve bone mineralization in childhood: Follow-up of a randomized clinical trial

BACKGROUND

Exposure to vitamin D in early life has been associated with improved bone mineralization, but no studies have investigated the combined effect of pregnancy supplementation and childhood 25(OH)D concentrations on bone health.

METHODS

We analyzed the effect of serum 25(OH)D concentrations at age 6 months and 6 years and the combined effect with prenatal high-dose vitamin D (2800 vs. 400 IU/day) on bone mineral density (BMD) and content (BMC) assessed by dual-energy X-ray absorptiometry (DXA) scans at age 3 and 6 years and longitudinal risk of fractures in a double-blinded, randomized clinical trial in the Copenhagen Prospective Studies on Asthma in Childhood 2010 (COPSAC₂₀₁₀) mother-child cohort with enrollment from March 4, 2009, to November 17, 2010, and clinical follow-up until January 31, 2019 (NCT00856947). All participants randomized to intervention and with complete data were included in the analyses.

FINDINGS

At age 6 months, serum 25(OH)D concentration was measured in 93% (n = 541) of 584 children. Children with sufficient (≥ 75 nmol/l) vs. insufficient (< 75 nmol/l) concentrations did not have lower risk of fractures: incidence rate ratio (95% CI); 0.64 (0.37;1.11), p = 0.11. However, vitamin D sufficient children from mothers receiving high-dose supplementation during pregnancy had a 60% reduced incidence of fractures compared with vitamin D insufficient children from mothers receiving standard-dose: 0.40 (0.19;0.84), p = 0.02.At age 6 years, serum 25(OH)D concentration was measured in 83% (n = 318) of 383 children with available DXA data. Whole-body bone mineralization was higher in vitamin D sufficient children at age 6 years; BMD, adjusted mean difference (aMD) (95% CI): 0.011 g/cm² (0.001;0.021), p = 0.03, and BMC, aMD: 12.3 g (-0.8;25.4), p = 0.07, with the largest effect in vitamin D sufficient children from mothers receiving high-dose vitamin D supplementation; BMD, aMD: 0.016 g/cm² (0.002;0.030), p = 0.03, and BMC, aMD: 23.5 g (5.5;41.5), p = 0.01.

INTERPRETATION

Childhood vitamin D sufficiency improved bone mineralization and in combination with prenatal high-dose vitamin D supplementation reduced the risk of fractures.

FUNDING

The study was supported by The Lundbeck Foundation R16-A1694, The Danish Ministry of Health 903,516, The Danish Council for Strategic Research 0603-00280B and The European Research Council 946,228.

Metabolic bone disease in children with intestinal failure is not associated with the level of parenteral nutrition dependency

BACKGROUND & AIMS

Children on long-term home parenteral nutrition (HPN) are at increased risk of suboptimal growth and metabolic bone disease (MBD) i.e. decreased bone mineral density (BMD). The aims of this cross-sectional study were to assess growth and bone health in children on long term HPN and to identify risk factors for MBD.

METHODS

Children above the age of 5 years, stable on HPN for more than 2 years were included. Medical files were reviewed retrospectively and included demographics, gestational age, birth weight and height, indication for PN, age at PN start, duration of PN, number of weekly PN infusions, weight-for-age and height-for-age (SD), body mass index (BMI, kg/m²) as well as blood and urine analyses at the time of Dual X-ray absorptiometry (DXA) measurements. All BMD values were adjusted to statural age which corresponds to the 50th percentile of height. Growth failure (height-for-age ≤ -2SD) and MBD (at least one BMD measurement ≤ -2SD) were analyzed according to the indication of PN, duration of PN and PN dependency index (PNDI) by comparing means and performing logistic regression analysis. PNDI is the ratio of non-protein energy intake in HPN to resting energy expenditure using Schofield equations.

RESULTS

Forty children were assessed at 12.4 ± 4.5 years of age. Mean age at PN start was 1.1 ± 3.6 y (median 0.5). The indications for PN were short bowel syndrome (SBS, n = 21), chronic intestinal pseudo-obstruction syndrome (CIPOS, n = 10) and congenital enteropathies (CE, n = 9). The mean number of PN perfusions was 6 ± 1/week. PNDI was 110 ± 30%. The mean serum level of 25-OHD3 was suboptimal at 26.5 ± 9.1 ng/mL (66.2 ± 22.8 nmol/L). The mean concentrations of calcium, phosphorus, and parathyroid hormone (PTH) were in the normal ranges. Eight children (20%) had PTH levels above normal with low 25-OHD3 levels. The mean weight-for-age and height-for-age Z-scores SDS were 0.4 ± 0.9 and -0.5 ± 1.1 respectively. The actual height was lower than genetic target height (p < 0.001). The BMD Z-scores, adjusted to the 50th percentile of height, of the spine, the left femur and the whole body were: -1.1 ± 1.7, -1.2 ± 1.5 and -1.5 ± 1.8 SDS respectively. Children with CE had significantly lower BMD values than those with SBS and CIPOS (p = 0.01). Only two children had bone fractures after a mild trauma (5%).

CONCLUSIONS

All children on long-term PN, are at risk of low BMD. High dependency on PN (PNDI>120%) and very long-term PN (>10 years) do not appear to increase the risk of growth failure nor MBD. PN-related bone fractures were rare. Close follow-up remains mandatory.

Hypovitaminosis D and Cardiometabolic Risk Factors in Adolescents with Severe Obesity

BACKGROUND/OBJECTIVES

Obesity is associated with cardiometabolic risk factors and with Vitamin D deficiency. The aim of this study was to examine the relationship between 25(OH)D concentrations and cardiometabolic risk factors in adolescents with severe obesity.

SUBJECTS/METHODS

A cross-sectional clinical assessment (body mass index, fat mass index, fat-free mass index, waist-to-height ratio, and blood pressure) and metabolic study (triglycerides, total cholesterol, HDL-C, LDL-C, glucose, insulin, HOMA-IR, leptin, calcium, phosphorous, calcidiol, and PTH) were carried out in 236 adolescents diagnosed with severe obesity (BMI z-score > 3.0, 99th percentile), aged 10.2-15.8 years. The criteria of the US Endocrine Society were used for the definition of Vitamin D status.

RESULTS

Subjects with Vitamin D deficiency had significantly elevated values (p < 0.05) for BMI z-score, waist circumference, waist z-score, body fat percentage, fat mass index, systolic and diastolic blood pressure, total cholesterol, triglycerides, LDL-C, insulin, HOMA-IR, leptin, and PTH than subjects with normal Vitamin D status. There was a significant negative correlation (p < 0.05) of serum 25(OH)D levels with body fat percentage, FMI, systolic BP, total cholesterol, triglyceride, LDL-C, glucose, insulin, HOMA-IR, leptin, and PTH.

CONCLUSIONS

Low Vitamin D levels in adolescents with severe obesity were significantly associated with some cardiometabolic risk factors, including body mass index, waist circumference, fat mass index, high blood pressure, impaired lipid profile, and insulin resistance.

Muscular Fitness Mediates the Association between 25-Hydroxyvitamin D and Areal Bone Mineral Density in Children with Overweight/Obesity

The association between vitamin D [25(OH)D] and bone health has been widely studied in children. Given that 25(OH)D and bone health are associated with muscular fitness, this could be the cornerstone to understand this relationship. Hence, the purpose of this work was to examine if the relation between 25(OH)D and areal bone mineral density (aBMD) was mediated by muscular fitness in children with overweight/obesity. Eighty-one children (8-11 years, 53 boys) with overweight/obesity were included. Body composition was measured with dual energy X-ray Absorptiometry (DXA), 25(OH)D was measured in plasma samples and muscular fitness was assessed by handgrip and standing long jump tests (averaged z-scores were used to represent overall muscular fitness). Simple mediation analyses controlling for sex, years from peak height velocity, lean mass and season were carried out. Our results showed that muscular fitness z-score, handgrip strength and standing long jump acted as mediators in the relationship between 25(OH)D and aBMD outcomes (percentages of mediation ranged from 49.6% to 68.3%). In conclusion, muscular fitness mediates the association of 25(OH)D with aBMD in children with overweight/obesity. Therefore, 25(OH)D benefits to bone health could be dependent on muscular fitness in young ages.

Assessment of vitamin D status in Czech children

OBJECTIVE

Vitamin D deficiency is a global health problem. The aim of this study was to determine the proportion of Czech children with vitamin D deficiency and examine related factors.

METHODS

The study subjects were 419 healthy children aged 5 and 9 years. Severe vitamin D deficiency was defined as a serum 25(OH)D level of < 25 nmol/L (3% of children), deficiency as that of 25-50 nmol/L (24% of children), insufficiency as that of 50-75 nmol/L (40% of children) and sufficiency as that of > 75 nmol/L (34% of children).

RESULTS

Serum 25(OH)D levels varied mainly with season. The highest levels of 25(OH)D were reached in autumn (median: 79.0 nmol/L), followed by summer (median: 67.8 nmol/L) and winter (median: 56.0 nmol/L). The lowest median value (49.8 nmol/L) was detected in spring.

CONCLUSION

Children with sufficiency 25(OH)D levels were more frequently exposed to the sun and exposed a larger part of their body to the sun while spending time outdoors. Levels of 25(OH)D were also associated with using vitamin D supplements within six weeks before sampling.

Bone Mass Development in Childhood and Its Association with Physical Activity and Vitamin D Levels. The CHAMPS-Study DK

This longitudinal study examined associations of bone mass with physical activity and vitamin D level over more than 6 years through puberty. A total of 663 participants (320 boys) with mean age 9.6 years at baseline (10-17 years at follow-up), underwent dual energy X-ray absorptiometry, anthropometry and blood samples for vitamin D at least twice during the study period (with three possible time-points). Physical activity was assessed using accelerometers at follow-up. A positive association was found between percent time spent at vigorous physical activity and total-body less head bone mineral content (β = 5.8, p = 0.002). The magnitude of this association increased with maturational development; thus physical activity may have a greater influence on bone mass in the more mature participants. The vitamin D levels were also positively associated with bone mass. A high degree of tracking was observed with changes in anthropometric Z scores predictive of deviation from tracking. No environmental factor predicted deviation from tracking.

Vitamin D Intervention and Bone: A Randomized Clinical Trial in Fair- and Dark-skinned Children at Northern Latitudes

OBJECTIVES

The aim of the study was to evaluate vitamin D status and effects of vitamin D intervention on bone mineral density (BMD) and content (BMC) in children with fair and dark skin in Sweden during winter.

METHODS

In a 2-center prospective double-blinded randomized intervention study 5- to 7-year-old children (n = 206) with fair and dark skin in Sweden (55°N-63°N) received daily vitamin D supplements of 25 μg, 10 μg, or placebo (2 μg) during 3 winter months. We measured BMD and BMC for total body (TB), total body less head (TBLH), femoral neck (FN), and spine at baseline and 4 months later. Intake of vitamin D and calcium, serum 25-hydroxy vitamin D (S-25[OH]D), and related parameters were analyzed.

RESULTS

Despite lower S-25(OH)D in dark than fair-skinned children, BMD of TB (P = 0.012) and TBLH (P = 0.002) and BMC of TBLH (P = 0.04) were higher at baseline and follow-up in those with dark skin. Delta (Δ) BMD and BMC of TB and TBLH did not differ between intervention and placebo groups, but FN-BMC increased more among dark-skinned children in the 25 μg (P = 0.038) and 10 μg (P = 0.027) groups compared to placebo. We found no associations between Δ S-25(OH)D, P-parathyroid hormone, P-alkaline phosphatase, and Δ BMD and BMC, respectively.

CONCLUSIONS

BMD and BMC remained higher in dark- than fair-skinned children despite lower vitamin D status. Even though no difference in general was found in BMD or BMC after vitamin D intervention, the increase in FN-BMC in dark-skinned children may suggest an influence on bone in those with initially insufficient vitamin D status.

Associations of Low Vitamin D and Elevated Parathyroid Hormone Concentrations With Bone Mineral Density in Perinatally HIV-Infected Children

BACKGROUND

Perinatally HIV-infected (PHIV) children have, on average, lower bone mineral density (BMD) than perinatally HIV-exposed uninfected (PHEU) and healthy children. Low 25-hydroxy vitamin D [25(OH)D] and elevated parathyroid hormone (PTH) concentrations may lead to suboptimal bone accrual.

METHODS

PHIV and PHEU children in the Pediatric HIV/AIDS Cohort Study had total body (TB) and lumbar spine (LS) BMD and bone mineral content (BMC) measured by dual-energy x-ray absorptiometry; BMD z-scores (BMDz) were calculated for age and sex. Low 25(OH)D was defined as ≤20 ng/mL and high PTH as >65 pg/mL. We fit linear regression models to estimate the average adjusted differences in BMD/BMC by 25(OH)D and PTH status and log binomial models to determine adjusted prevalence ratios of low 25(OH)D and high PTH in PHIV relative to PHEU children.

RESULTS

PHIV children (n = 412) were older (13.0 vs. 10.8 years) and more often black (76% vs. 64%) than PHEU (n = 207). Among PHIV, children with low 25(OH)D had lower TB-BMDz [SD, -0.38; 95% confidence interval (CI), -0.60 to -0.16] and TB-BMC (SD, -59.1 g; 95% CI, -108.3 to -9.8); high PTH accompanied by low 25(OH)D was associated with lower TB-BMDz. Among PHEU, children with low 25(OH)D had lower TB-BMDz (SD, -0.34; 95% CI, -0.64 to -0.03). Prevalence of low 25(OH)D was similar by HIV status (adjusted prevalence ratio, 1.00; 95% CI, 0.81 to 1.24). High PTH was 3.17 (95% CI, 1.25 to 8.06) times more likely in PHIV children.

CONCLUSIONS

PHIV and PHEU children with low 25(OH)D may have lower BMD. Vitamin D supplementation trials during critical periods of bone accrual are needed.

Hypertrophic Scars: Are Vitamins and Inflammatory Biomarkers Related with the Pathophysiology of Wound Healing?

BACKGROUND

Hypertrophic scars are a consequence of wound healing.

OBJECTIVE

The objective of the present study is to evaluate vitamin D and inflammatory biomarker plasma levels during wound healing.

METHODS

A prospective study was performed in patients (n = 63) submitted to body contouring surgery. Blood samples were collected before (t ₀) and 5 days after surgery (t ₅). Blood cell count, protein inflammatory biomarkers, and circulating plasma levels of 25(OH)D, vitamin A and vitamin E were quantified. Six months after surgery, scars were evaluated and classified as normal or hypertrophic.

RESULTS

At the end of the study, 73% of the patients developed a normal scar (control group, n = 46) and 27% of the patients presented hypertrophic scars (HT group, n = 17). The patients in the HT group presented higher eosinophil (0.145 × 10⁹ /L vs. 0.104 × 10⁹ /L, p = 0.028) and basophil count (0.031 × 10⁹ /L vs. 0.22 × 10⁹ /L, p = 0.049) and C-reactive protein levels (6.12 mg/L vs. 2.30 mg/L, p = 0.015) in t ₀ than the patients in the control group. At t ₅, the patients in the HT group showed a decrease in neutrophil (3.144 × 10^9/L vs. 4.03 × 10⁹/L, p = 0.031) and an increase in basophil (0.024 × 10⁹/L vs. 0.015 × 10⁹/L, p = 0.005) and lymphocyte count (1.836 × 10⁹ /L vs. 1.557 × 10⁹/L; p = 0.028). Before surgery, vitamin D plasma levels were found to be decreased by almost 50% (23.52 ng/mL vs. 15.46 ng/mL, p = 0.031) in the patients who developed hypertrophic scars. Thirty-one percent of the patients submitted to bariatric surgery had more hypertrophic scars, versus 24% of the patients with no previous bariatric surgery.

CONCLUSION

There is a different systemic inflammatory profile response in the patients during the formation of hypertrophic scars. Vitamin D plasma levels are marked reduced in these patients. Considering the powerful anti-inflammatory effect of vitamin D, these findings could be related.

Vitamin D status of Icelandic children and its influence on bone accrual

The importance of vitamin D for children's bone health has been well established, but the effects of less severe deficiency are not fully known. The main objective of this study was to assess the vitamin D status of Icelandic children at the age of 7, and again at 9 years of age, and the association of vitamin D status with bone mineral content and bone accrual over 2 years. We invited 321 children to participate in this study, and 267 (83 %) took part; 211 (79 %) underwent a DXA scan and 164 were again scanned 2 years later; 159 (60 %) vitamin D samples were measured and 119 (75 %) were measured again 2 years later. At age 7, 65 % of the children had vitamin D concentrations <50 nmol/l, and at age 9 this figure was 60 %. At age 7, 43 % of the children had insufficient amounts of vitamin D (37.5-50 nmol/l), and 22 % had a vitamin D deficiency (<37.5 nmol/l). In linear regression analysis, no association was found between vitamin D and bone mineral content. Furthermore, there was no significant difference in bone accrual over 2 years for the children with insufficient or deficient vitamin D at both ages, compared to those having more than 50 nmol/l at both time points. More than 60 % of Icelandic children have inadequate concentrations of vitamin D in serum repeatedly over a 2-year interval. However, vitamin D in the range did not have a significant effect on bone mineral content or accrual at ages 7 and 9.

Seasonal variations in calcidiol and parathyroid hormone levels in healthy children and adolescents in Navarre, Spain: a cross-sectional study

Objective

To analyze the seasonal variations in calcidiol and parathyroid hormone serum levels along a natural year in a paediatric population living in a region of the north of Spain considering a normal nutrition status.

Design

A cross-sectional study.

Setting

Navarra Hospital Complex, Pamplona, Spain.

Participants

A total of 413 Caucasian individuals (aged 3.1 to 15.4 years): 227 school children (96 males and 131 females) and 186 adolescents (94 males and 92 females), with normal nutritional status.

Main outcome measures

Clinical examination (sex, age, weight, height and body mass index) and blood testing (calcium, phosphate, alkaline phosphatase, calcidiol and parathyroid hormone) during the year 2014.

Results

Calcidiol levels were lower during spring (25.96 ± 6.64 ng/mL) and reached its maximum level in summer (35.33 ± 7.51 ng/mL); parathyroid hormone levels were lower in summer (27.13 ± 7.89 pg/mL) and reached maximum level in autumn (34.73 ± 15.38 pg/mL). Hypovitaminosis D prevalence was 14.3% in summer and 75.3% in spring. Parathyroid hormone levels were compatible with secondary hyperparathyroidism in eight individuals (1.9%). There is a correlation (p < 0.01) between calcidiol and parathyroid hormone (r = −0.336). Logistic regression showed significant increased risk of hypovitaminosis in females (OR:1.63) and adolescents (OR:1.77), and when blood samples taken in autumn (OR:12.22), winter (OR:8.54) and spring (OR:19.72).

Conclusions

There is a high prevalence of hypovitaminosis D in the paediatric population with a healthy nutrition situation in Navarre, mainly during the months of autumn and winter, and, especially, in spring time. Given the difficulties in maintaining a sufficient amount of body vitamin D content along the year, it should be considered to give vitamin supplements and/or increase the intake of its natural dietary sources or vitamin D fortified foods.

Conflicting reports on vitamin D supplementation: Evidence from randomized controlled trials

A significant number of children and adolescents worldwide have low serum 25(OH)D values relative to the 2010 Institute of Medicine criteria. Since approximately 90% of adult bone mineral content (BMC) is accrued by the end of adolescence, and approximately 40% of adult BMC accumulated during the 4 years surrounding peak BMC velocity, low circulating 25(OH)D during this time may attenuate gains in adolescent bone strength. Reduced bone mineralization and strength during pubertal growth tracks into adulthood and could lead to an increased risk of skeletal fractures. Observational studies examining the relationships between vitamin D and bone are conflicting and few randomized controlled trials (RCTs) have been conducted in children and adolescents. Four of these RCTs, however, provide moderate support for the role of vitamin D supplementation on BMC accrual in adolescent females with baseline serum concentrations <50 nmol/L. Though the daily vitamin D doses employed in these trials ranged from 200 to 3000 IU per day, it is not clear if a dose-response effect exists. Specific maturational stages were associated with optimal bone responses in each of these trials, but they were not consistent across studies. Furthermore, data on male children and among ethnicities other than white and Asian youth were limited in these studies and therefore reduce the generalizability of the findings. Finally, the evidence linking vitamin D supplementation to improved muscle gains and function, important variables to consider in bone health investigations during growth, might imply indirect effects of supplementation on bone. In conclusion, future RCTs are warranted that address the mechanisms by which vitamin D improves bone mineralization in adolescents, including trials that address the impact of vitamin D on muscle function.

Vitamin D and skeletal health in infancy and childhood

During growth, severe vitamin D deficiency in childhood can result in symptomatic hypocalcaemia and rickets. Despite the suggestion from some studies of a secular increase in the incidence of rickets, this observation may be driven more by changes in population demographics than a true alteration to age, sex and ethnicity-specific incidence rates; indeed, rickets remains uncommon overall and is rarely seen in fair-skinned children. Additionally, the impact of less severe vitamin D deficiency and insufficiency has received much interest in recent years, and in this review, we consider the evidence relating vitamin D status to fracture risk and bone mineral density (BMD) in childhood and adolescence. We conclude that there is insufficient evidence to support the suggestion that low serum 25-hydroxyvitamin D [25(OH)D] increases childhood fracture risk. Overall, the relationship between 25(OH)D and BMD is inconsistent across studies and across skeletal sites within the same study; however, there is evidence to suggest that vitamin D supplementation in children with the lowest levels of 25(OH)D might improve BMD. High-quality randomised trials are now required to confirm this benefit.

Possible contributions of skin pigmentation and vitamin D in a polyfactorial model of seasonal affective disorder

Seasonal affective disorder (SAD) is a polyfactorial and polygenetic disorder that involves biological and psychological sub-mechanisms that differentially involve depression, seasonality, circadian rhythms, retinal sensitivity, iris pigmentation, sleep factors, and the neurotransmitters involved with these systems. Within the framework of the polyfactorial conceptualization of SAD, we review the possible contributions of vitamin D3 with respect to the aforementioned sub-mechanisms. We hypothesize that rather than functioning primarily as a proximal or direct sub-mechanism in the etiology of SAD, vitamin D likely functions in a more foundational and regulative role in potentiating the sub-mechanisms associated with the depressive and seasonality factors. There are several reasons for this position: 1. vitamin D levels fluctuate in the body seasonally, with a lag, in direct relation to seasonally-available sunlight; 2. lower vitamin D levels have been observed in depressed patients (as well as in patients with other psychiatric disorders) compared to controls; 3. vitamin D levels in the central nervous system affect the production of both serotonin and dopamine; and 4. vitamin D and vitamin D responsive elements are found throughout the midbrain regions and are especially concentrated in the hypothalamus, a region that encompasses the circadian timing systems and much of its neural circuitry. We also consider the variable of skin pigmentation as this may affect levels of vitamin D in the body. We hypothesize that people with darker skin pigmentation may experience greater risks for lower vitamin D levels that, especially following their migration to regions of higher latitude, could contribute to the emergence of SAD and other psychiatric and physical health problems.

Vitamin D, the immune system and asthma

The effects of vitamin D on bone metabolism and calcium homeostasis have long been recognized. Emerging evidence has implicated vitamin D as a critical regulator of immunity, playing a role in both the innate and cell-mediated immune systems. Vitamin D deficiency has been found to be associated with several immune-mediated diseases, susceptibility to infection and cancer. Recently, there has been increasing interest in the possible link between vitamin D and asthma. Further elucidation of the role of vitamin D in lung development and immune system function may hold profound implications for the prevention and treatment of asthma.

Vitamin D status and bone mineral density in African American children with Crohn disease

BACKGROUND

Vitamin D deficiency and low bone mineral density (BMD) are complications of inflammatory bowel disease. Vitamin D deficiency is more prevalent among African Americans compared with whites. There are little data comparing differences in serum 25-hydroxyvitamin D (25OHD) concentrations and BMD between African American and white children with Crohn disease (CD).

METHODS

We compared serum 25OHD concentrations of African American children with CD (n = 52) to white children with CD (n = 64) and healthy African American controls (n = 40). We also analyzed BMD using dual-energy x-ray absorptiometry results from our pediatric CD population.

RESULTS

African American children with CD had lower serum 25OHD concentrations (16.1 [95% confidence interval, CI 14.5-17.9] ng/mL) than whites with CD (22.3 [95% CI 20.2-24.6] ng/mL; P < 0.001). African Americans with CD and controls exhibited similar serum 25OHD concentration (16.1 [95% CI 14.5-17.9] vs 16.3 [95% CI 14.4-18.4] ng/mL; NS). African Americans with CD exhibited no difference in serum 25OHD concentration when controlling for seasonality, disease severity, and surgical history, although serum 25OHD concentration was significantly decreased in overweight children (body mass index ≥85%, P = 0.003). Multiple regression analysis demonstrated that obese African American girls with CD had the lowest serum 25OHD concentrations (9.6 [95% CI 6.8-13.5] ng/mL). BMD was comparable between African American and white children with CD (z score -0.4 ± 0.9 vs -0.7 ± 1.2; NS).

CONCLUSIONS

African American children with CD are more likely to have vitamin D deficiency compared with white children with CD, but have similar BMD. CD disease severity and history of surgery do not affect serum 25OHD concentrations among African American children with CD. African American children have low serum 25OHD concentrations, independent of CD, compared with white children. Future research should focus on how race affects vitamin D status and BMD in children with CD.

Genetic influences on vitamin D status and forearm fracture risk in African American children

We sought to investigate the relationship between newly identified genetic variants and vitamin D levels and fracture risk in healthy African American (black) children. This case-control study included children of both sexes, ages 5 to 9 years, with and without forearm fractures. Serum 25-hydroxy vitamin D levels, bone mineral density, body mass index, and calcium/vitamin D intake were measured in 130 individuals (n = 60 cases and n = 70 controls). The 5 variants tested were located in the GC gene (rs2282679), in the NADSYN1 gene (rs12785878 and rs3829251), and in the promoter region of the CYP2R1 gene (rs2060793 and rs104741657). Associations between single nucleotide polymorphisms (SNPs) and vitamin D levels were tested using an analysis of covariance. Associations between SNPs and fracture status were tested using logistic regression. The GC gene variant was associated with vitamin D levels (P = 0.038). None of the SNPs were associated with fracture status in young blacks. These results suggest that the variants tested, which are associated with circulating vitamin D levels in whites, are not associated with fracture status in healthy black children. Additional research is required to discover the genetics of fracture risk in blacks.

Vitamin D deficiency and low bone mineral density in pediatric and young adult intestinal failure

OBJECTIVES

The aim of the present study was to determine the prevalence and predisposing factors for vitamin D deficiency and low bone mineral density (BMD) in patients with intestinal failure (IF).

METHODS

A retrospective review of patients with IF managed at the Cincinnati Children's Hospital Medical Center. IF was defined as history of parenteral nutrition (PN) >30 days. Vitamin D deficiency was defined as serum 25-hydroxyvitamin D (25 (OH) D) <20 ng/dL. Reduced BMD was defined using dual x-ray absorptiometry z score ≤-2. A binary logistic regression model was used to test for association of significant risk factors and the outcome variables after univariate analyses.

RESULTS

One hundred and twenty-three patients with median age of 4 years (range 3-22 years) were evaluated. Forty-nine (39.8%) patients had at least a documented serum 25 (OH) D deficiency during the study interval, whereas 10 of 80 patients (12.5%) with dual x-ray absorptiometry scans completed had a low BMD z score. Age at study entry was associated with both 25 (OH) D deficiency (P = 0.01) and low BMD z score (P = 0.03). Exclusive PN at study entry was associated with reduced bone mass (P = 0.03). There was no significant association between vitamin D deficiency and low BMD z score (P = 0.31).

CONCLUSIONS

The risk of 25 (OH) D deficiency and low BMD z score increases with age among patients with IF. Strategies for monitoring and preventing abnormal bone health in older children receiving exclusive PN need to be developed and evaluated.

A systematic review of vitamin D status in populations worldwide

Vitamin D deficiency is associated with osteoporosis and is thought to increase the risk of cancer and CVD. Despite these numerous potential health effects, data on vitamin D status at the population level and within key subgroups are limited. The aims of the present study were to examine patterns of 25-hydroxyvitamin D (25(OH)D) levels worldwide and to assess differences by age, sex and region. In a systematic literature review using the Medline and EMBASE databases, we identified 195 studies conducted in forty-four countries involving more than 168 000 participants. Mean population-level 25(OH)D values varied considerably across the studies (range 4·9-136·2 nmol/l), with 37·3 % of the studies reporting mean values below 50 nmol/l. The highest 25(OH)D values were observed in North America. Although age-related differences were observed in the Asia/Pacific and Middle East/Africa regions, they were not observed elsewhere and sex-related differences were not observed in any region. Substantial heterogeneity between the studies precluded drawing conclusions on overall vitamin D status at the population level. Exploratory analyses, however, suggested that newborns and institutionalised elderly from several regions worldwide appeared to be at a generally higher risk of exhibiting lower 25(OH)D values. Substantial details on worldwide patterns of vitamin D status at the population level and within key subgroups are needed to inform public health policy development to reduce risk for potential health consequences of an inadequate vitamin D status.

Racial differences in cortical bone and their relationship to biochemical variables in Black and White children in the early stages of puberty

Osteoporotic fracture rates differ according to race with Blacks having up to half the rate of Whites. The current study demonstrates that racial divergence in cortical bone properties develops in early childhood despite lower serum 25-hydroxyvitamin D in Blacks.

INTRODUCTION

Racial differences in bone structure likely have roots in childhood as bone size develops predominantly during growth. This study aimed to compare cortical bone health within the tibial diaphysis of Black and White children in the early stages of puberty and explore the contributions of biochemical variables in explaining racial variation in cortical bone properties.

METHODS

A cross-sectional study was performed comparing peripheral quantitative computed tomography-derived cortical bone measures of the tibial diaphysis and biochemical variables in 314 participants (n = 155 males; n = 164 Blacks) in the early stages of puberty.

RESULTS

Blacks had greater cortical volumetric bone mineral density, mass, and size compared to Whites (all p < 0.01), contributing to Blacks having 17.0 % greater tibial strength (polar strength-strain index (SSIP)) (p < 0.001). Turnover markers indicated that Blacks had higher bone formation (osteocalcin (OC) and bone-specific alkaline phosphatase) and lower bone resorption (N-terminal telopeptide) than Whites (all p < 0.01). Blacks also had lower 25-hydroxyvitamin D (25(OH)D) and higher 1,25-dihydroxyvitamin D (1,25(OH)2D) and parathyroid hormone (PTH) (all p < 0.05). There were no correlations between tibial bone properties and 25(OH)D and PTH in Whites (all p ≥ 0.10); however, SSIP was negatively and positively correlated with 25(OH)D and PTH in Blacks, respectively (all p ≤ 0.02). Variation in bone cross-sectional area and SSIP attributable to race was partially explained by tibial length, 25(OH)D/PTH, and OC.

CONCLUSIONS

Divergence in tibial cortical bone properties between Blacks and Whites is established by the early stages of puberty with the enhanced cortical bone properties in Black children possibly being explained by higher PTH and OC.

Vitamin D: an overview of its role in skeletal muscle physiology in children and adolescents

Many children may have insufficient serum concentrations of vitamin D, which could prevent optimal muscle development and function. Vitamin D deficiency in animal models results in negative effects on muscle fiber structure and calcium/phosphorus handling, suggesting an integral role of vitamin D in skeletal muscle function. While there is a dearth of data in humans, the available evidence demonstrates a positive association between vitamin D status and muscle function. This review focuses on the important role of vitamin D in muscle function in children and adolescents who live in North American regions where exposure to ultraviolet B radiation is limited and who are thus at increased risk for vitamin D insufficiency. The effects of vitamin D on muscle cell proliferation and differentiation, muscle fiber structure, and calcium and phosphorus handling are discussed. Moreover, the roles of vitamin D and the vitamin D receptor and their genomic and nongenomic actions in muscle function are explored in depth. Future research should aim to establish a vitamin D status consistent with optimal musculoskeletal development and function in young children.

A global representation of vitamin D status in healthy populations

PURPOSE

This paper visualizes the available data on vitamin D status on a global map, examines the existing heterogeneities in vitamin D status and identifies research gaps.

METHODS

A graphical illustration of global vitamin D status was developed based on a systematic review of the worldwide literature published between 1990 and 2011. Studies were eligible if they included samples of randomly selected males and females from the general population and assessed circulating 25-hydroxyvitamin D [25(OH)D] levels. Two different age categories were selected: children and adolescents (1-18 years) and adults (>18 years). Studies were chosen to represent a country based on a hierarchical set of criteria.

RESULTS

In total, 200 studies from 46 countries met the inclusion criteria, most coming from Europe. Forty-two of these studies (21 %) were classified as representative. In children, gaps in data were identified in large parts of Africa, Central and South America, Europe, and most of the Asia/Pacific region. In adults, there was lack of information in Central America, much of South America and Africa. Large regions were identified for which the mean 25(OH)D levels were below 50 nmol/L.

CONCLUSIONS

This study provides an overview of 25(OH)D levels around the globe. It reveals large gaps in information in children and adolescents and smaller but important gaps in adults. In view of the importance of vitamin D to musculoskeletal growth, development, and preservation, and of its potential importance in other tissues, we strongly encourage new research to clearly define 25(OH)D status around the world.

Vitamin D intake in young children with acute lower respiratory infection

OBJECTIVE

To determine if vitamin D intake is associated with acute lower respiratory infections (ALRI) in children.

METHODS

The vitamin D intakes of children younger than 5 years of age admitted to hospital with either bronchiolitis or pneumonia were compared to an unmatched control group of the same age without respiratory infection. Caregivers of 197 children completed a questionnaire collecting information on demographic variables, ALRI risk factors and diet. Associations of ALRI with vitamin D intake and other ALRI risk factors were determined.

RESULTS

The mean vitamin D intake of children with ALRI was 48 IU/kg/d compared to 60 IU/kg/d in the control group. When controlling for age, ethnicity, socio-economic status, northern residence, breastfeeding, immunizations and smoking contact, children with a vitamin D intake of less than 80 IU/kg/d were greater than 4 times more likely to have ALRI compared to children with a vitamin D intake exceeding 80 IU/kg/day (OR 4.9, 95% CI: 1.5, 16.4).

CONCLUSIONS

A higher vitamin D intake than currently recommended might be needed to offer protection against diseases such as ALRI. Increased vitamin D supplementation could have important public health consequences, as bronchiolitis and pneumonia are the most common reasons for hospitalization in young children.

Demographic, dietary, and biochemical determinants of vitamin D status in inner-city children

BACKGROUND

Reports of clinical rickets are particularly evident in minority infants and children, but only limited analyses of vitamin D are available in this demographic group.

OBJECTIVE

We sought to characterize circulating 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)(2)D], and their determinants, including circulating parathyroid hormone (PTH), total alkaline phosphatase activity (ALP), calcium, and phosphorus, in minority infants and children.

DESIGN

We obtained demographic information and blood samples for measurement of PTH, ALP, 25(OH)D, and 1,25(OH)(2)D in >750 6-mo- to 3-y-old children. Dietary intake data were obtained and analyzed.

RESULTS

The mean (±SD) 25(OH)D concentration was 66 ± 22 nmol/L (26.3 ± 8.7 ng/dL). A total of 15% of children had 25(OH)D concentrations less than the recommended target threshold of 50 nmol/L. Combined elevations of PTH and ALP occurred in only 2.5% of children. Determinants of 25(OH)D included vitamin D intake, age (decreasing with age), skin type (greater concentrations in lighter-skinned children than in darker-skinned children), formula use (higher intakes), season (greater concentrations in the summer and fall than in the winter and spring), and, inversely, PTH. The mean 1,25(OH)(2)D concentration was 158 ± 58 pmol/L (60.6 ± 22.5 pg/mL), which was consistent with a reference range of 41-274 pmol/L or 15.7-105.5 pg/mL. Determinants for 1,25(OH)(2)D were age (decreasing with age), sex (greater concentrations in girls than in boys), skin type (greater concentrations in lighter-skinned children than in darker-skinned children), and, inversely, serum calcium and phosphorus.

CONCLUSIONS

Although 15% of subjects were vitamin D insufficient, only 2.5% of subjects had elevations of both PTH and ALP. The greater 25(OH)D concentrations observed with formula use confirm that dietary vitamin D fortification is effective in this demographic group. Circulating 1,25(OH)(2)D is higher in infants than in older children and adults and, in contrast to 25(OH)D, is not directly correlated with nutrient intakes.

Frequency of vitamin D insufficiency in healthy children between 1 and 16 years of age in Turkey

BACKGROUND

The aim of this study was to establish the frequencies of vitamin D deficiency and insufficiency among healthy children aged 1-16 years and also to determine the factors affecting the levels of vitamin D in Turkey.

METHODS

A total of 849 healthy individuals whose ages ranged from 1 to 16 years were included in the study. Serum 25(OH)D, calcium, phosphorous and alkaline phosphatase l levels were measured at the end of the winter period. The approximate daily calcium intake was calculated by using a 1-week diet history.

RESULTS

We determined that the prevalence of vitamin D deficiency (<20 ng/mL) was 8% and that of vitamin D insufficiency (20-29 ng/mL) was 25.5% in the population investigated. The average daily intake of calcium was especially low in the >8-year-old age group (<1300 mg/day).

CONCLUSION

Vitamin D insufficiency was found to be very common in the population investigated. The daily calcium intake was below the adequate levels especially in school children. Vitamin D supplementation after the first year of life could be beneficial especially for school children and adolescents. The government must develop public policies for the fortification of milk, milk products, and fruit juices with vitamin D.

High prevalence of vitamin D deficiency in school-age children in Tehran, 2008: a red alert

OBJECTIVE

To assess the vitamin D status of 9-12-year-old primary-school children in Tehran during autumn and winter 2007-2008.

DESIGN

A descriptive cross-sectional study.

SETTING

Primary schools of Tehran city, Iran.

SUBJECTS

A total of 1111 children aged 9-12 years (573 boys and 538 girls) from sixty primary schools were enrolled in the study. Weight, height, BMI and serum levels of Ca, P, Mg, 25-hydroxyvitamin D (25(OH)D), intact parathyroid hormone (iPTH), osteocalcin and bone-specific alkaline phosphatase of all the participants were assessed. Dietary Ca intake was also evaluated using a quantitative FFQ for a subsample of the study population (n 503). Vitamin D sufficiency was defined on the basis of serum levels of 25(OH)D as either ≥37 nmol/l (criterion 1) or ≥50 nmol/l (criterion 2).

RESULTS

Daily intake of Ca did not differ significantly between boys and girls (929·6 (sd 436·7) mg and 909·5 (sd 465·5) mg, respectively). However, on the basis of the first criterion, approximately 86 % of the children had vitamin D deficiency, with 38·3 % being severely deficient (25(OH)D < 12·5 nmol/l). According to the second criterion, prevalence of vitamin D deficiency rose to 91·7 %. Prevalence of vitamin D deficiency was higher in girls than in boys by either criterion. Serum levels of 25(OH)D inversely correlated with iPTH (r = -0·154, P < 0·001) and BMI (r = -0·092, P = 0·002) but directly correlated with duration of sun exposure (r = 0·115, P < 0·001).

CONCLUSIONS

The high prevalence of vitamin D deficiency among schoolchildren (especially among girls) warrants immediate interventions for proper nutritional support.

Forearm fractures in children and bone health

PURPOSE OF REVIEW

Summary highlighting the evidence that bone health may affect forearm fracture risk in children.

RECENT FINDINGS

Although the incidence of other fractures and injuries are decreasing, the incidence of forearm fractures is increasing in otherwise healthy children. There is a growing volume of research that forearm fracture risk in children may be related to deficiencies in parameters of bone health. Available evidence of this relationship was summarized and included direct links to bone health (measurement of bone properties), indirect links to bone health (diet, vitamin D status, BMI), and genetic analyses.

SUMMARY

There is consistent and convincing evidence of an association between bone mineral density and forearm fracture risk in children. Studies of calcium intake and supplementation are less extensive in scope but suggest that effects of calcium deficiency on the radius may contribute to childhood forearm fracture risk. Forearm fracture risk in obese children is likely to reflect a combination of suboptimal bone health status and behavioral characteristics. Published data on the role of vitamin D status and genetic factors are limited but merit further consideration. Further investigation is needed to better understand the factors contributing to forearm fracture risk in children and translate this knowledge into effective clinical prevention and practice.

Adverse interaction of low-calcium diet and low 25(OH)D levels on lumbar spine mineralization in late-pubertal girls

No consensus has been reached on the serum 25-hydroxyvitamin D [25(OH)D] levels required to ensure optimal bone health around menarche. We searched for a possible interaction of 25(OH)D levels and calcium intake on lumbar spine mineralization and on biologic features of bone metabolism in healthy late-pubertal girls. Lumbar spine parameters (ie, area, mineral content, and density) and calcium intake were evaluated in 211 healthy white adolescent girls at pubertal stages IV-V (11 to 16.9 years), together with biologic markers of calcium and bone metabolism and with International External Quality Assessment Scheme for Vitamin D Metabolite (DEQAS)-validated serum 25(OH)D levels. A high prevalence of 25(OH)D levels ≤ 30 nmol/L (41%), ≤ 40 nmol/L (61%), and ≤ 50 nmol/L (70%) was found during winter-spring. Parathyroid hormone (PTH) levels were inversely associated with 25(OH)D levels (p = .0021). In contrast, lumbar spine mineral content and density were not associated with 25(OH)D, excepted when calcium intake was below 600 mg/day (p = .0081). Girls with such low calcium intake and 25(OH)D levels of 40 nmol/L or less (9% of the cohort) had a 0.4 to 0.7 SD lower mean areal bone mineral density Z-score than girls with higher calcium intake and/or higher 25(OH)D status. The adverse association between lumbar spine mineralization and combined calcium deficiency-low 25(OH)D levels remained significant in the 91 girls who could be followed over 4 years after their initial evaluation. We conclude that low 25(OH)D levels (≤40 nmol/L) are observed frequently during winter-spring in late-pubertal European girls, which may exacerbate the negative impact of calcium deficiency on lumbar spine mineralization.

Factors influencing the vitamin D status of 10-year-old urban South African children

OBJECTIVE

Assessment of vitamin D status in a cohort of healthy 10-year-old urban children and the factors that influence vitamin D status in these children.

DESIGN

A cross-sectional study. Blood samples were collected across four seasons of the year for the biochemical determination of serum 25-hydroxyvitamin D [25(OH)D]. Anthropometric measurements (height and weight), BMI and total fat and lean mass (determined by the dual energy X-ray absorptiometry) were measured. 25(OH)D concentrations were assessed by chemiluminescent assay.

SETTING

Study of children in the Greater Johannesburg area of South Africa who form the Bone Health sub-cohort of the longitudinal Birth to Twenty cohort.

SUBJECTS

Three hundred and eighty-five children who form the Bone Health sub-cohort of the longitudinal Birth to Twenty cohort.

RESULTS

White children had significantly higher 25(OH)D than their black peers (120·0 (sd 36·6) nmol/l v. 93·3 (sd 34·0) nmol/l, respectively). Seasonal variations in 25(OH)D levels were found only in white children, with 25(OH)D levels being significantly higher in white than in black children during the autumn and summer months. In multiple regression analysis, season, ethnicity, sex and total fat mass were the factors found to have an influence on 25(OH)D. Vitamin D deficiency (7 %) and insufficiency (19 %) were uncommon among the 10-year-old children.

CONCLUSIONS

Vitamin D supplementation or fortification is not warranted in healthy children living in Johannesburg. However, further studies need to confirm this in other regions of the country, especially in those living further south and with less sunshine during the winter months.

Predictors of vitamin D status and its association with parathyroid hormone in young New Zealand children

BACKGROUND

Despite increased awareness of the adverse health effects of low vitamin D status, few studies have evaluated 25-hydroxyvitamin D [25(OH)D] status in young children.

OBJECTIVES

We aimed to assess vitamin D status on the basis of 25(OH)D and its relation with parathyroid hormone (PTH) and to identify possible predictors of 25(OH)D status in young children living in a country with minimal vitamin D fortification.

DESIGN

Serum 25(OH)D and PTH concentrations were measured in a cross-sectional sample of children aged 12-22 mo [n = 193 for 25(OH)D, n = 144 for PTH] living in Dunedin, New Zealand (latitude: 45 degrees S). Anthropometric, dietary, and sociodemographic data were collected.

RESULTS

The majority of children sampled in the summer (94%; 47 of 50) had 25(OH)D >50 nmol/L; however, nearly 80% of children sampled in the winter (43 of 55) had serum concentrations < or =50 nmol/L. In season-adjusted multivariate analysis, breastfeeding and higher levels of education were independently associated with lower 25(OH)D concentrations, whereas male sex and cigarette-smoke exposure were positively associated with 25(OH)D (all P < 0.05). Fractional polynomial regression was used to describe the nonlinear relation between serum PTH and 25(OH)D (P < 0.001). When 25(OH)D concentrations were >60-65 nmol/L, a plateau in PTH was evident.

CONCLUSIONS

Seasonal variation in 25(OH)D concentration implies that postsummer vitamin D stores were insufficient to maintain status >50 nmol/L year-round. Examination of the predictors of 25(OH)D in our model shows few modifiable risk factors, and thus effective dietary strategies may be required if future research determines that children with 25(OH)D concentrations <50 nmol/L are at significant health risk. This trial was registered at www.actr.org.au as ACTRN12605000487617.

25-hydroxyvitamin D status of healthy, low-income, minority children in Atlanta, Georgia

OBJECTIVES

The goals were to determine the prevalence of vitamin D deficiency among minority children in a southern US city, to examine differences in serum 25-hydroxyvitamin D levels between non-Hispanic black and Hispanic children, and to determine dietary sources of vitamin D.

METHODS

Low-income, minority children (N = 290; mean age: 2.5 +/- 1.2 years) were recruited during well-child clinic visits. Serum 25-hydroxyvitamin D and calcium levels were measured and dietary information was assessed.

RESULTS

The mean 25-hydroxyvitamin D(3) level was 26.2 +/- 7.6 ng/mL, whereas 25-hydroxyvitamin D(2) was not detected. Overall, 22.3% of children had deficient serum 25-hydroxyvitamin D(3) levels (< or =20 ng/mL), 73.6% had less-than-optimal serum 25-hydroxyvitamin D levels (< or =30 ng/mL), and 1.4% had low serum calcium levels (< or =9 mg/dL). A significantly larger proportion of non-Hispanic black children, compared with Hispanic children, had vitamin D deficiency (26% vs 18%; P < .05). Age and season of recruitment were significantly associated with vitamin D deficiency and low serum calcium levels. Older children (> or =3 years) were less likely to have vitamin D deficiency (odds ratio [OR]: 0.89 [95% confidence interval [CI]: 0.81-0.96]; P < .001). Study enrollment during spring and summer reduced the likelihood of vitamin D deficiency by approximately 20% (spring, OR: 0.85 [95% CI: 0.73-0.98]; P = .03; summer, OR: 0.82 [95% CI: 0.73-0.92]; P < .01). Fortified milk provided most dietary vitamin D (62%), with Hispanic children reporting greater intake.

CONCLUSIONS

Suboptimal vitamin D status was common among apparently healthy, low-income, minority children. Age and season were significant predictors of vitamin D deficiency.

Vitamin D insufficiency and deficiency in children with early chronic kidney disease

OBJECTIVE

To assess the prevalence of abnormal vitamin D status in children and adolescents with chronic kidney disease (CKD).

STUDY DESIGN

This was an outpatient cross-sectional, retrospective study of 258 patients, mean age 12.3 +/- 5.2 years, with an average estimated glomerular filtration rate (eGFR) of 106 +/- 51 mL/min/1.73 m2 (range, 0 to 220 mL/min/1.73 m2). Serum 25-hydroxy-vitamin D [25(OH)D], calcium, phosphorus, and parathyroid hormone levels, as well as selected anthropometric variables, were analyzed.

RESULTS

Reduced 25(OH)D concentrations (< 30 ng/mL) were found in 60% of the patients. In 28%, the concentration was < 20 ng/mL, indicating vitamin D deficiency. Patients with more advanced CKD were more likely to have vitamin D deficiency compared with those with incipient CKD or normal GFR (42% vs 26%; P = .03) and displayed more prominent hyperparathyroidism. Suboptimal vitamin D status was similar in males and females, but was significantly more prevalent in older (P < .01), non-Caucasian (P < .01), and overweight (P = .02) patients. Patients with early-stage CKD (eGFR > 60 mL/min/1.73 m2) and with vitamin D deficiency were significantly shorter than their counterparts with 25(OH)D levels > 20 ng/mL (P = .02).

CONCLUSIONS

Vitamin D insufficiency and deficiency are very prevalent in pediatric patients across all stages of CKD, particularly in non-Caucasian and obese patients, and may contribute to growth deficits during the earliest stages of CKD.

Plasma 25-hydroxyvitamin D levels in young children undergoing placement of tympanostomy tubes

OBJECTIVES

We report the plasma 25-hydroxyvitamin D [25(OH)D] levels of 16 young children who were undergoing ambulatory surgery for placement of tympanostomy tubes.

METHODS

We previously obtained blood samples from young children who were undergoing ambulatory surgery and reported that they had lower blood levels than adults of eicosapentaenoic acid (an omega-3 fatty acid), vitamin A, and selenium. Plasma frozen continuously at -80 degrees C was available from 16 subjects who were undergoing placement of tympanostomy tubes.

RESULTS

The mean (+/- SD) age of the patients was 3.7 +/- 1.6 years (median, 2.9 years; range, 1.9 to 7.4 years). Sixty-two percent were male; half were white, and half were Hispanic. Sixty-two percent were private patients; the parents reported that half were taking vitamin supplements. None had a history of rickets. None had 25(OH)D levels less than 10 ng/mL; 50% had 25(OH)D levels less than 20 ng/mL (deficient in adults); another 31% had levels from 21 to 29 ng/mL (insufficient in adults).

CONCLUSIONS

Vitamin D is essential for the production of endogenous antimicrobial peptides, and has been linked to seasonal, epidemic influenza A. However, the level of 25(OH)D needed to prevent infection with various human pathogens has not been defined. In view of increasing bacterial resistance and emerging new pathogens, further research on the relationship of infection to 25(OH)D and other nutritional factors is warranted.

Vitamin D status and calcium metabolism in adolescent black and white girls on a range of controlled calcium intakes

BACKGROUND

There are limited data in adolescents on racial differences in relationships between dietary calcium intake, absorption, and retention and serum levels of calcium-regulating hormones.

OBJECTIVES

The aim of this study was to investigate these relationships cross-sectionally in American White and Black adolescent girls.

METHODS

Calcium balance studies were conducted in 105 girls, aged 11-15 yr, on daily calcium intakes ranging from 760-2195 mg for 3-wk controlled feeding periods; 158 observations from 52 Black and 53 White girls were analyzed.

RESULTS

Black girls had lower serum 25-hydroxyvitamin D [25(OH)D], higher serum 1,25-dihydroxyvitamin D, and higher calcium absorption and retention than White girls. Calcium intake and race, but not serum 25(OH)D, predicted net calcium absorption and retention with Black girls absorbing calcium more efficiently at low calcium intakes than White girls. The relationship between serum 25(OH)D and serum PTH was negative only in White girls. Calcium intake, race, and postmenarcheal age explained 21% of the variation in calcium retention, and serum 25(OH)D did not contribute further to the variance.

CONCLUSIONS

These results suggest that serum 25(OH)D does not contribute to the racial differences in calcium absorption and retention during puberty.

Vitamin D: a growing perspective

Vitamin D deficiency has been widely reported in all age groups in recent years. Rickets has never been eradicated in developed countries, and it most commonly affects children from recent immigrant groups. There is much evidence that current vitamin D guidelines for the neonatal period, 5-10 microg (200-400 IU)/day, prevent rickets at the typical calcium intakes in developed countries. The annual incidence of vitamin D-deficiency rickets in developed countries ranges between 2.9 and 7.5 cases per 100,000 children. The prevalence of vitamin D deficiency in mothers and their neonates is remarkable, and the results of one study suggest that third-trimester 25-hydroxyvitamin D (25(OH)D) is associated with fetal bone mineral accrual that may affect prepubertal bone mass accumulation. Beyond infancy, the evidence indicates that 5 microg (200 IU)/day of vitamin D has little effect on vitamin D status as measured by the serum 25(OH)D concentration. Two randomized clinical trials show that higher vitamin D intake improves one-year gain in bone density in adolescent girls. The functions of vitamin D extend beyond bone to include immune system regulation and anti-proliferative effects on cells. Early life vitamin D inadequacy is implicated in the risk of bone disease, autoimmune disease, and certain cancers later in life; however, long-term interventional studies do not exist to validate the widespread implementation of greater vitamin D consumption. Here we review the available data concerning vitamin D status and health effects of vitamin D in pregnancy through to and including adolescence.

Vitamin D deficiency in children and its management: review of current knowledge and recommendations

Given the recent spate of reports of vitamin D deficiency, there is a need to reexamine our understanding of natural and other sources of vitamin D, as well as mechanisms whereby vitamin D synthesis and intake can be optimized. This state-of-the-art report from the Drug and Therapeutics Committee of the Lawson Wilkins Pediatric Endocrine Society was aimed to perform this task and also reviews recommendations for sun exposure and vitamin D intake and possible caveats associated with these recommendations.

Serum tumor necrosis factor-alpha concentrations are negatively correlated with serum 25(OH)D concentrations in healthy women

Background

Circulating 25 hydroxyvitamin D (25 (OH)D), an accurate measure of vitamin D status, is markedly greater in individuals with increased exposure to ultraviolet B (UVB) light via sunlight or the use of artificial UV light. Aside from the known relationship between vitamin D and bone, vitamin D has also been implicated in immune function and inflammation. Furthermore, a mass of evidence is accumulating that vitamin D deficiency could lead to immune malfunction. Our overall objective was to study the relationship between vitamin D status (as determined by serum 25(OH) D concentrations) and inflammatory markers in healthy women.

Methods

This observational study included 69 healthy women, age 25–82 years. Women with high UVB exposure and women with minimal UVB exposure were specifically recruited to obtain a wide-range of serum 25(OH)D concentrations. Health, sun exposure and habitual dietary intake information were obtained from all subjects. Body composition was determined by dual-energy-x-ray absorptiometry. A fasting blood sample was collected in the morning and analyzed for serum 25(OH)D, parathyroid hormone (iPTH), estradiol (E₂), cortisol, and inflammatory markers [tumor necrosis factor -alpha (TNF-α), interleukin-6 and -10 (IL-6, IL-10), and C-reactive protein (CRP)].

Results

Women with regular UVB exposure (Hi-D) had serum 25(OH)D concentrations that were significantly higher (p < 0.0001) and iPTH concentrations that were significantly lower (p < 0.0001) than women without regular UVB exposure (Lo-D). Although IL-6, IL-10, and CRP did not have a statistically significant relationship with 25(OH)D concentrations, linear regression models revealed a significant inverse relationship between serum 25(OH)D and TNF-α concentrations. This relationship remained significant after controlling for potential covariates such as body fat mass, menopausal status, age, or hormonal contraceptive use.

Conclusion

Serum 25(OH)D status is inversely related to TNF-α concentrations in healthy women, which may in part explain this vitamin's role in the prevention and treatment of inflammatory diseases. Results gleaned from this investigation also support the need to re-examine the biological basis for determining optimal vitamin D status.

[Biochemical measures in the German Health Interview and Examination Survey for Children and Adolescents (KiGGS)]

In the framework of the German Health Interview and Examination Survey for Children and Adolescents (KiGGS) a variety of biochemical parameters was determined in order to provide objective information on health status and particular health risks, in addition to parent interview data and anthropometric measurements. Overall 43 parameters covered three areas of particular public health interest: micronutrient deficiency, seroepidemiology of infectious diseases and immunization status, and risk indicators or risk factors for chronic non-communicable diseases. A review of available evidence regarding valid reference or cutoff values as well as the standardization of laboratory methods led to the categorization of these parameters into five classification categories. Here, we discuss the present first descriptive results on selected parameters representing the various categories. In order to determine the public health impact of measurement results, and perhaps even derive normative reference data relevant to health care, more detailed analyses will be required. In the first step, these will focus on cross-sectional analyses of the association between biochemical parameters and other health-related anthropometric and sociodemographic variables. Intermediate and long-term objectives will include the construction of multidimensional reference values taking into account several laborato ry data and other clinical information at the same time, and the prognostic validation of reference or cut-off values based on a follow- up of the study participants for clinical outcomes.

Vitamin D deficiency: A global perspective

Vitamin D is essential for the maintenance of good health. Its sources can be skin production and diet intake. Most humans depend on sunlight exposure (UVB 290-315 nm) to satisfy their requirements for vitamin D. Solar ultraviolet B photons are absorbed by the skin, leading to transformation of 7-dehydrocholesterol into vitamin D3 (cholecalciferol). Season, latitude, time of day, skin pigmentation, aging, sunscreen use, all influence the cutaneous production of vitamin D3. Vitamin D deficiency not only causes rickets among children but also precipitates and exacerbates osteoporosis among adults and causes the painful bone disease osteomalacia. Vitamin D deficiency has been associated with increased risk for other morbidities such as cardiovascular disease, type 1 and type 2 diabetes mellitus and cancer, especially of the colon and prostate. The prevalence of hypovitaminosis D is considerable even in low latitudes and should be taken into account in the evaluation of postmenopausal and male osteoporosis. Although severe vitamin D deficiency leading to rickets or osteomalacia is rare in Brazil, there is accumulating evidence of the frequent occurrence of subclinical vitamin D deficiency, especially in elderly people.

Risk factors for low serum 25-hydroxyvitamin D concentrations in otherwise healthy children and adolescents

BACKGROUND

Serum 25-hydroxyvitamin D [25(OH)D] concentrations serve as a biomarker for vitamin D stores. Prior studies have not examined the risk factors for low vitamin D concentrations in a multiethnic sample of US youth across a broad age range.

OBJECTIVE

The objective was to determine the prevalence of and factors associated with low concentrations of 25(OH)D in children and adolescents.

DESIGN

Serum 25(OH)D concentrations were measured in 382 healthy children aged 6-21 y living in the northeastern United States. Dietary and supplemental vitamin D intake was assessed by interview. Fat and lean mass were assessed by dual-energy X-ray absorptiometry. Multivariable ordinal logistic regression was used to determine factors associated with decreased concentrations of 25(OH)D.

RESULTS

The median concentration of 25(OH)D was 28 ng/mL (interquartile range: 19-35 ng/mL), and 55% of subjects had 25(OH)D concentrations <30 ng/mL. 25(OH)D concentrations were inversely correlated with parathyroid hormone concentrations (Spearman's r=-0.31, P<0.001) but were not significantly correlated with 1,25-dihydroxyvitamin D concentrations. In the multivariable model, older age (P<0.001), black race [odds ratio (OR): 14.2; 95% CI: 8.53, 23.5], wintertime study visit (OR: 3.55; 95% CI: 2.29, 5.50), and total daily vitamin D intake <200 IU (OR: 1.58; 95% CI: 1.02, 2.46) were associated with low vitamin D concentrations. Fat and lean mass were not independently associated with vitamin D status in this healthy-weight sample.

CONCLUSION

Low serum 25(OH)D concentrations are prevalent in otherwise healthy children and adolescents in the northeastern United States and are related to low vitamin D intake, race, and season.

Elevated blood lead concentrations and vitamin D deficiency in winter and summer in young urban children

BACKGROUND

It is widely recognized that blood lead concentrations are higher in the summer than in winter. Although the effects of some environmental factors such as lead in dust on this phenomenon have been studied, relationships to sunlight-induced vitamin D synthesis have not been adequately investigated. Vitamin D status is influenced by the diet, sunlight exposure, age, skin pigmentation, and other factors, and may modify gastrointestinal lead absorption or release of lead stored in bones into the bloodstream.

OBJECTIVE AND METHODS

We collected paired blood samples from 142 young, urban African-American and Hispanic children in the winter and summer to study the seasonal increase in blood lead and its relationships to vitamin D nutrition, age, and race.

RESULTS

A winter/summer (W/S) increase in blood lead concentrations of 32.4% was found for children 1-3 years of age. There was a smaller W/S increase of 13.0% in children 4-8 years of age. None of the 51 Hispanic children had an elevated blood lead concentration (> or = 10 microg/dL) during the winter, and only one had an elevated summertime concentration. In contrast, elevated blood lead concentrations were frequent in the 91 African-American children, especially those 1-3 years of age. For the latter, the percentage with elevated blood lead levels increased from 12.2% in winter to 22.5% in summer. A 1.2% W/S increase in serum 25-hydroxy-vitamin D (serum 25-OH-D) concentrations was found for children 1-3 years of age. However, in children 4-8 years of age the W/S increase in serum 25-OH-D was much larger-33.6%. The percentages of children with low (< 16 microg/L) serum 25-OH-D concentrations were 12.0% in winter and 0.7% in summer and were consistently greater in African-American than in Hispanic children. The seasonal increases in blood lead and serum 25-OH-D in children 4-8 years of age were significantly associated.

CONCLUSION

The higher summertime serum 25-OH-D concentrations for the 4- to 8-year-old children are likely caused by increased sunlight-induced vitamin D synthesis and may contribute to the seasonal increase in blood lead. Age and race are key factors that affect blood lead and vitamin D nutrition, as well as their interactions, in young urban children.

Peripheral bone mineral density and its predictors in healthy school girls from two different socioeconomic groups in Delhi

Peripheral bone density measurements are scarce and the factors, which predict bone mineral density at these sites, especially in children, are not clearly known. In this study, age, height, weight and alkaline phosphatase had a significant association on peripheral bone mineral density in healthy Indian school girls.

INTRODUCTION

Factors that lead to the attainment of peak bone mass at peripheral sites, during period of growth are not clearly known.

METHODS

Six-hundred and sixty-four randomly selected 7- to 17-year-old girls from upper and lower socioeconomic status (USES/LSES) schools were assessed clinically and a recording of their height and weight was undertaken. Serum calcium, phosphorus, total alkaline phosphatase (ALP), 25-hydroxyvitamin D (25-OHD) and parathyroid hormone (PTH) were measured in all of them. Bone mineral density (BMD) was measured at the distal forearm (BMDdf) and calcaneum (BMDca) by peripheral dual energy X-ray absorptiometry (pDXA).

RESULTS

Girls belonging to the USES were significantly taller (149.7 +/- 12.3 cm vs 144.4 +/- 11.9 cm; P < 0.001) and weighed more (44.3 +/- 12.9 kg vs 35.9 +/- 10.0 kg; P < 0.001) than girls from the LSES. USES girls had a significantly higher mean serum calcium (9.3 +/- 0.7 mg/dl vs 9.2 +/- 0.8 mg/dl; P < 0.05) and significantly lower alkaline phosphatase (316 +/- 166 IU/l vs 423 +/- 228 IU/l; P < 0.01) and iPTH (29.9 +/- 18.4 pg/ml vs 45.7 +/- 64.6 pg/ml; P < 0.01). There was no significant difference in mean serum phosphorus and 25-OHD levels between the two groups. USES subjects had higher BMD at both sites than LSES subjects. BMDdf and BMDca increased with age and tended to plateau by 16 years and 12 years of age respectively in both the groups. Age, height and weight explained approximately 50% of the variability, while biochemical parameters explained approximately 30% of variability in BMD at both the sites. The only biochemical parameter which had a significant association with BMD was ALP at the distal forearm.

CONCLUSION

In conclusion, age, nutrition, height and weight are significantly associated with BMD at peripheral sites.

A prospective analysis of plasma 25-hydroxyvitamin D concentrations in white and black prepubertal females in the southeastern United States

BACKGROUND

Little is known regarding changes in vitamin D status among children living in the southern United States and whether these changes are race-dependent.

OBJECTIVES

The aims were to prospectively assess plasma 25-hydroxyvitamin D [25(OH)D] concentrations in prepubertal black and white girls (n = 83) living in northeast Georgia and to determine whether 25(OH)D concentrations change with increasing age.

DESIGN

Plasma samples were obtained annually over a time frame of 1-7 y, and 25(OH)D concentrations were assessed by using radioimmunoassay. Percentage body fat (%BF) and fat-free soft tissue (FFST) mass were measured by using dual-energy X-ray absorptiometry. Linear mixed-effects models were used with height, weight, body mass index percentile, %BF, FFST, pubertal stage, dietary intake, physical activity, and socioeconomic status as covariates.

RESULTS

Plasma 25(OH)D values < 80 nmol/L were observed in 75% of the participants. Plasma 25(OH)D values (analyzed on the natural logarithm scale) decreased with increasing age (P = 0.02), independent of race. Plasma 25(OH)D values were higher in whites than in blacks (P < 0.0001), and the amount of this difference depended on season (P < 0.001 for all seasons). A significant negative association between FFST and 25(OH)D, beyond the effects of age, race, and season (P = 0.007), was observed. The effects of age, race, and season on 25(OH)D remained significant when dietary calcium, vitamin D, and physical activity were used as covariates; however, after adjustment for FFST, only the effects of race and season remained.

CONCLUSIONS

White girls living in the southeastern United States have higher 25(OH)D concentrations than do black girls, and the magnitude of this difference depends on the season. Decreases in 25(OH)D with age are associated with increases in FFST. Whether FFST requires additional vitamin D during growth remains to be determined.

Resurrection of vitamin D deficiency and rickets

The epidemic scourge of rickets in the 19th century was caused by vitamin D deficiency due to inadequate sun exposure and resulted in growth retardation, muscle weakness, skeletal deformities, hypocalcemia, tetany, and seizures. The encouragement of sensible sun exposure and the fortification of milk with vitamin D resulted in almost complete eradication of the disease. Vitamin D (where D represents D2 or D3) is biologically inert and metabolized in the liver to 25-hydroxyvitamin D [25(OH)D], the major circulating form of vitamin D that is used to determine vitamin D status. 25(OH)D is activated in the kidneys to 1,25-dihydroxyvitamin D [1,25(OH)2D], which regulates calcium, phosphorus, and bone metabolism. Vitamin D deficiency has again become an epidemic in children, and rickets has become a global health issue. In addition to vitamin D deficiency, calcium deficiency and acquired and inherited disorders of vitamin D, calcium, and phosphorus metabolism cause rickets. This review summarizes the role of vitamin D in the prevention of rickets and its importance in the overall health and welfare of infants and children.