Vitamin D deficiency and associated factors in adolescent girls in Beijing

Relationship of Vitamin D Deficiency with Cervical Vertebral Maturation and Dental Age in Adolescents: A Cross-Sectional Study

Background

Considering the high prevalence of vitamin D deficiency and its effect on growth and development, the assessment of the dental age and skeletal age with regard to vitamin D deficiency status could influence the treatment planning of growth modification treatment. This study aimed to assess the relationship between vitamin D deficiency, cervical vertebral maturation (CVM) as an indicator of skeletal age, and dental age in adolescent patients.

Methods

In this cross-sectional study, the chronological age of 52 orthodontic patients aged between 10 and 14 years was recorded, and their serum level of vitamin D was determined using a radioimmunoassay test. The patients were then divided into three groups based on their serum vitamin D level: severe deficiency, moderate deficiency, and the control group with normal vitamin D. The panoramic radiographs of patients were assessed to determine their dental age using Demirjian's method. CVM was determined on lateral cephalograms using Baccetti's classification to specify the skeletal age. Data were analyzed using a t-test, linear regression, ordinal logistic regression, and Pearson's correlation coefficient (at P < 0.05, confidence interval = 95%).

Results

Skeletal age showed a significant difference between the group with severe vitamin D deficiency and the control group (P=0.01); however, such difference was not observed between the group with moderate vitamin D deficiency and the control group (P=0.12). Dental age was not significantly different between the groups with vitamin D deficiency and the control group (P=0.26 for severe, and P=0.39 for moderate deficiency).

Conclusions

A less advanced skeletal maturation was observed in adolescents with severe vitamin D deficiency; however, dental development was not affected by this deficiency. Vitamin D status is better to be considered in decision-making for the initiation of growth modification orthodontic treatments.

Vitamin D status and determinants in Indian children and adolescents: a multicentre study

Studies performed on Indian children to assess vitamin-D status have been on small sample sizes, limited to specific geographical locations and used non-standard methods to measure 25(OH)D₃. This multicentre study assessed 25(OH)D₃ concentrations from dried blood spots (DBS) in 5–18-year-old Indian children and adolescents using a standardized protocol and identified factors contributing towards vitamin D deficiency. Cross-sectional, observational school-based study was conducted by multi-stage stratified random sampling. A city and nearby village were selected from 6 Indian states covering wide geographical areas. Demography, anthropometry, body-composition, dietary-intakes and DBS samples were collected. 25(OH)D₃ was assessed from DBS using Liquid chromatography with tandem-mass spectrometry. Vitamin-D status was assessed in 2500 children; with additional data collected on a subset (n = 669) to assess predictors. Mean vitamin-D concentration was 45.8 ± 23.9 nmol/L, 36.8% of subjects had sufficient vitamin-D (> 50 nmol/L); rural subjects and boys had higher concentrations (p < 0.05). On regression analysis, younger age, female-gender, overweight and urban residence significantly contributed to deficiency. More than half the Indian children/adolescents were vitamin-D deficient or insufficient. Our study reinforces vitamin-D deficiency as a major public health problem and the need for supplementation, food fortification and educating the population as initiatives required to improve sufficiency status.

Prevalence of Osteoporosis and Associated Risk Factors among Postmenopausal Women: A Cross-Sectional Study from Northern India

Context

Prevalence statistics of postmenopausal osteoporosis and knowledge regarding its independent predictors are lacking, especially in India, where every third woman and every eighth man is suffering from it.

Aim

This study aims to investigate the prevalence of osteoporosis and associated risk factors among postmenopausal women.

Study Settings and Design

This was a hospital-based prospective cross-sectional study.

Methods

This study was carried out among postmenopausal women, who attended orthopaedics outpatient department from August 2020 to July 2021 and 587 women ranging in age between 50 and 80 years who had confirmed menopause were enrolled for the study. Finally, 539 women were recommended for bone mineral density testing, using dual energy X-ray absorptiometry.

Statistical Analysis

To analyze the differences between the groups, a Chi-square and Student's t-test were used for the categorical and continuous variables, respectively. P < 0.05 was considered to show significant associations.

Results

In our study, 54.7% of subjects belonged to <60 years of age group. Half of the subjects (51.9%) were illiterate. 37.7% of subjects were having 6 or more children. 14.5% of subjects were currently smoking or chewing tobacco. Age of menopause among 38.0% of subjects was after 50 years of age and duration of menopause at the time of enrolment in the study was more than 10 years in 48.8% of subjects. The prevalence of osteoporosis increased with the increase in the parity and increased number of abortions. Subjects with family history of symptoms related to osteoporosis, and fragility fracture; and self-history of fragility fracture had higher prevalence of osteoporosis (P < 0.05).

Conclusion

In our study, the overall prevalence of osteoporotic fractures among postmenopausal females was 82.2% (osteoporosis: 37.5% and osteopenia: 44.7%). The findings of current study and previous studies clearly indicate the urgent need of collective efforts towards the growing problem of osteoporosis in postmenopausal women.

Association study of the serum 25(OH)D concentration and myopia in Chinese children

To analyze the serum 25 hydroxyvitamin D (25[OH]D) concentration in Chinese children with myopia and explore its correlation with myopia.From July to September in 2019, myopic children were collected from the Myopia Influencing Factors Survey Project. The basic information and vision related behaviors of the subjects were collected by questionnaire. The diopter of the children without dilated pupils was measured by the computerized refractometer. Meanwhile, 5 ml fasting venous blood samples were collected for the determination of serum 25(OH)D concentration.A total of 186 children were included in this study, including 90 males and 96 females, with an average age of 8 ± 3.26 years. The detection rate of serum 25(OH)D deficiency in myopic children was 65.59% (122/186). There was statistical significance in the detection rate of serum 25(OH)D deficiency in children with different myopic degrees (χ2 = 6.635, P = .010). The average serum 25(OH)D concentration in myopic children was 14.86 (10.67-18.96) ng/ml, and the difference of serum 25(OH)D concentration in children with different myopia degrees was statistically significant (Z = 20.23, P < .001). Logistic regression analysis showed that after controlling for gender, parental myopia, after-school class, and outdoor activities, the prevalence of developing moderate and high myopia was 2.051 times (95% confidence interval: 1.272-3.724) higher in the serum 25(OH)D deficiency group than in the serum 25(OH)D sufficiency group. There is a positive correlation between serum 25(OH)D concentration and the equivalent spherical degree of myopic children.The study found that serum 25(OH)D concentration is closely related to the prevalence of myopia in Chinese children. The results further support the conclusion that children with a higher level of serum 25(OH)D have a lower prevalence of moderate to high myopia. The results of this study provide a basis for further research into the relationship between vitamin D and visual development in children and its mechanisms.

Vitamin D status in pubertal children

BACKGROUND

Optimal vitamin D status has a great importance in puberty, which is a period of peak bone mineral acquisition. In this study, we aimed to assess the effect of pubertal period on vitamin D status.

METHODS

The study included totally 200 healthy children, aged between 4 and 14 years. Group 1 included 100 prepubertal, children, aged between 4 and 8 years. Group 2 included 100 pubertal children, aged between 9 and 14 years. They had no chronic illnesses. Ages, heights, weights, genders, Body Mass Indexes (BMIs), socioeconomic and educational status of families were established. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured by high performance liquid chromatography (HPLC). Serum parathyroid hormone (PTH) was evaluated using an immunoradiometric assay kit. Serum calcium (Ca), phosphorus (P) and alkaline phosphatase (ALP) levels were measured.

RESULTS

We determined that 25(OH)D levels were lower with higher PTH levels in the group aged 9 to 14 years (pubertal children), compared to the group aged 4 to 8 (prepubertal children). Gender, weight, height or BMI, family socioeconomic and education status did not affect serum 25(OH)D levels of children in each group.

CONCLUSIONS

We demonstrated that vitamin D deficiency was more commonly seen in the pubertal children, compared to pre pubertal period. Children should be supported with vitamin D supplements during the puberty, which has a great importance for rapid increase in bone mass.

Demographic Differences and Trends of Vitamin D Levels Among the Teenaged Girls in Balochistan

Background

Vitamin D is a vital micronutrient and plays a vital role in defining the bone mineral density of an individual. There are many factors that regulate the levels of vitamin D in our body. The deficiency in vitamin D leads to various complications, with the most important one weakening of bones. Adolescence defines the degree of bone mineral density, which reduces with the growing age in a gradual fashion.

Methods

The study was a cross-sectional study conducted in Zarghoon town, Quetta, Pakistan. A sample size of 142 was taken from urban and rural areas. Participants were adolescent girls falling in the age bracket of 13-18 years. The circulating level of 25-hydroxy vitamin D was assessed using the ELISA (enzyme-linked immunosorbent assay) technique. Data were analyzed with SPSS Version 20 (IBM Corp.).

Results

Overall, vitamin D deficiency was 32.4%, and 9.9 % of girls were found to be severely deficient, where the highest proportion belonged to urban samples. The prevalence rate of vitamin D insufficiency was 39.4%. The urban population had a higher prevalence of low levels of vitamin D. In urban respondents, 49.1% had an insufficient vitamin D level, 33.3% had a deficient vitamin D level, and 17.5% had a severely deficient vitamin D level. In rural respondents, 47.1% had normal vitamin D levels, 32.9% had insufficient vitamin D levels, 15.3% were deficient, and 4.7% were severely deficient.

Conclusion

It was concluded that vitamin D deficiency has a high prevalence among adolescent girls of school age. Additionally, it is more prevalent in urban areas than in rural areas.

The relationship between serum 25-hydroxy vitamin D and blood pressure and quality of life in overweight and obese patients with type 2 diabetes mellitus compared with healthy subjects

Background:

Vitamin D is one of the known lipoprotein hormones with metabolic properties. We aimed to determine the serum 25-hydroxy vitamin D concentration in overweight/obese subjects with diabetes mellitus type Ⅱ (DM Ⅱ) in association with systolic and diastolic blood pressure and quality of life compared with healthy participants.

Methods:

The current case-control study was carried out among 80 overweight/obese subjects with DM Ⅱ, and 77 healthy subjects matched by sex, age and body mass index (BMI). Serum 25-hydroxyvitamin D concentration was measured by ELISA method. In order to examine the quality of life, the Persian version of SF36 questionnaire was used.

Results:

There was significant difference between diabetic and healthy subjects considering serum 25-hydroxyvitamin D concentration (p=0.012). Serum 25-hydroxyvitamin D concentration was inversely correlated with diastolic blood pressure (p=0.02) and positively associated with physical function (p<0.001), social function (p<0.001) and general health (p<0.001) components of quality of life in diabetic subjects and physical health sub-scale (p=0.004) in all participants.

Conclusion:

Serum 25-hydroxyvitamin D concentration was significantly lower in diabetic subjects in comparison with healthy controls. There was a significant reverse relationship between serum concentrations of 25-hydroxyvitamin D with diastolic blood pressure and on the other hand, a significant positive relationship with physical function, social function and general health components and physical health subscale of quality of life in participants with DM Ⅱ.

Vitamin D Status in Egyptian Adolescent Females with Iron Deficiency Anemia and Its Correlation with Serum Iron Indices

Background:

In Egypt, it seems that adolescent girls are a candidate for Vitamin D Deficiency (VDD), mostly due to inadequate sun exposure as a result of the culture and social dress codes and dietary factors. Currently, there is growing evidence that VDD is associated with Iron Deficiency Anemia (IDA).

Aim:

To investigate the frequency of VDD in adolescent females with IDA in comparison to healthy control and demonstrate whether VD level was correlated with serum iron indices.

Subjects and Methods:

Forty adolescent females with known cases of IDA (group 1) and 30 healthy females matched for age as a control (group 2) were selected. We compared the differences between the two groups to determine the degree of VD level; where VDD was defined as 25-hydroxyvitamin D [25(OH)D] ≤20 ng/mL, vitamin D insufficiency (VDI) as 25(OH) D of 20-30 ng/mL, and vitamin D sufficiency (VDS) as 25(OH)D >30 ng/mL. Body mass index (BMI), complete blood count (CBC), serum iron, total iron binding capacity (TIBC), serum ferritin, serum creatinine, ionized calcium and 25(OH)D were measured for all participants.

Results:

We found that subnormal vitamin D (VDD and VDI) was more frequent in the IDA group (75%) than control (40%), (p = 0.025); where 19 adolescent female patients (47.5%) were VDD, 11 (27.5%) were VDI and 10 (25%) were VDS, while in the control group, VDD was present in 4 (20%), VDI in 4 (20%) and VDS in 12 (60%) respectively. There was not any significant correlation between serum VD and serum iron indices (r =0.168, p < 0.05) and Hb (r = 0.360, p < 0.001). There was no significant difference in serum hemoglobin level between IDA patients with subnormal VD and those with VDS. The mean level of serum 25(OH) D was significantly lower in winter months than summer in both groups; (16.87 vs. 31.57 mg/dL, p < 0.001) and (31.9 vs. 35.04 mg/dL, p < 0.001) respectively. BMI, Iron, TIBC and seasonal variation were not predictors of 25(OH) D levels in adolescent girls with IDA.

Conclusion:

VDD has a higher frequency in Egyptian adolescent females with IDA than healthy control. However, vitamin D levels were not significantly correlated with iron indices. Our result might direct the attention for measuring vitamin D level in patients with IDA with the possibility of VD supplementation with iron.

A critical review of the role of milk and other dairy products in the development of obesity in children and adolescents

Existing reviews suggest that milk and other dairy products do not play a role in the development of obesity in childhood, but they do make an important contribution to children's nutrient intake. It is thus curious that public health advice on the consumption of dairy products for children is often perceived as unclear. The present review aimed to provide an overview of the totality of the evidence on the association between milk and other dairy products, and obesity and indicators of adiposity, in children. Our search identified forty-three cross-sectional studies, thirty-one longitudinal cohort studies and twenty randomised controlled trials. We found that milk and other dairy products are consistently found to be not associated, or inversely associated, with obesity and indicators of adiposity in children. Adjustment for energy intake tended to change inverse associations to neutral. Also, we found little evidence to suggest that the relationship varied by type of milk or dairy product, or age of the children, although there was a dearth of evidence for young children. Only nine of the ninety-four studies found a positive association between milk and other dairy products and body fatness. There may be some plausible mechanisms underlying the effect of milk and other dairy products on adiposity that influence energy and fat balance, possibly through fat absorption, appetite or metabolic activity of gut microbiota. In conclusion, there is little evidence to support a concern to limit the consumption of milk and other dairy products for children on the grounds that they may promote obesity.

Use of Stable Calcium Isotopes (42Ca & 44Ca) in Evaluation of Calcium Absorption in Beijing Adolescents with Low Vitamin D Status

Female adolescent populations with low calcium intakes and sub-optimal vitamin D status are found in northern China. Whether these individuals are able to adapt by enhancing calcium absorption and reducing calcium excretion for maximizing calcium retention is unknown. This study examined the association between true-fractional-calcium-absorption (TFCA), plasma 25-hydroxyvitamin-D, and urinary calcium excretion among adolescents in Northern China. Twelve healthy girls 9 to 17 years old were recruited from Beijing during a winter. Calcium intake, anthropometry, pubertal status, plasma 25-hydroxyvitamin-Ds (25-OHD), serum calcium, and urinary calcium were determined. TFCA was evaluated by dual stable calcium isotopes. The mean ± SD calcium intake, 24-hour urinary calcium excretion, plasma 25-OHD and TFCA were 591 ± 164 mg/day, 79.9 ± 49.6 mg/day, 30.5 ± 9.8 nmol/L, and 60.4 ± 14.4%, respectively. TFCA was inversely correlated with 25-OHD (r = −0.73, p = .008). Urinary calcium was correlated with the onset of menarche (r = 0.63, p = .027). Post-menarcheal girls had a higher urinary calcium output than premenarcheal girls (p = .03). Adolescents from north China with sub-optimal vitamin-D status are able to adapt by enhancing TFCA and reducing urinary calcium excretion to retain calcium for bone development. TFCA was inversely correlated with plasma 25-OHD. Whether a higher efficiency of calcium absorption is sustainable if the shortfall of vitamin D persisting remains to be studied.

Current Vitamin D Status in Healthy Japanese Infants and Young Children

This study aimed to characterize serum 25-hydroxyvitamin D (25OH-D) values among Japanese children aged ≤48 mo. The study included 290 healthy infants and young children aged 0-48 mo (males/females=166/124) living in Shizuoka or Tokyo. The subjects were divided into three groups by age (Low Age: 0-5, Middle Age: 6-15, High Age: 16-48 mo). The vitamin D deficient state was defined as 25OH-D <12 ng/mL, the insufficient state as 12-20 ng/mL, and the sufficient state as >20 ng/mL. The seasonal variation of serum 25OH-D levels was also analyzed. The median serum 25OH-D levels in each group were: Low Age (n=50), 19 ng/mL; Middle Age (n=94), 30 ng/mL; and High Age (n=146), 30 ng/mL. The serum 25OH-D level was significantly lower in the Low Age group than in the other groups (p<0.01). Serum 25OH-D levels in summer and autumn (n=149) were significantly higher than in winter and spring (n=141) (33 vs. 25 ng/mL, p<0.01). In the Low Age group, there was a significant difference in serum 25OH-D levels between breast-fed infants (n=26) and formula-fed or mixed-fed infants (n=19) (12 vs. 32 ng/mL, p<0.01). However, there were no significant differences in 25OH-D levels between the two season classifications in either breast-fed or formula-fed and mixed-fed infants. Although clinical symptoms were not available, more than 75% of the breast-fed infants and 14.6% of infants and young children to whom food had been introduced were defined as having a vitamin D deficient or insufficient state. Breastfeeding seems one of the contributing factor to lower serum 25 OH-D levels among infants ≤5 mo of age.

Epidemiology and risk factors of hypovitaminosis D in a cohort of internationally adopted children: a retrospective study

Background

Predictors of hypovitaminosis D were extensively studied in the adult population, leading to an approximately complete understanding of them, while there is a lack of studies in the pediatric population, especially in migrant and internationally adopted children.

In this retrospective study, we tried to identify the major laboratory predictors of hypovitaminosis D in a cohort of internationally adopted children.

Methods

Data were extracted from the database of the “Ethnopediatrics Outpatient Clinic” of the “A. Gemelli” Foundation University Hospital in Rome, Italy. Our study included 873 children evaluated from March 2007 to May 2016. Analysis of variance, chi square test, t test and multivariate logistic regression were performed, a “p” value < 0.05 was considered significant, with a confidence interval of 95%.

Results

We did not find any significant correlation between Vitamin D and Calcium, Phosphates or Magnesium levels within the population we examined. Moreover, parathyroid hormone is not a good predictor of Vitamin D Status.

Conclusions

Considering the strong influence Vitamin D status has not only on bone health, but also on general well-being, it is due to perform a vitamin D assessment as soon as possible, especially in internationally adopted children.

Electronic supplementary material

The online version of this article (10.1186/s13052-018-0527-4) contains supplementary material, which is available to authorized users.

High prevalence of vitamin D deficiency and influencing factors among urban and rural residents in Tianjin, China

There was a high prevalence of vitamin D deficiency among residents in Tianjin, China, especially among female residents, rural young adults, and elderly individuals. This is the first large-scale study evaluating vitamin D status in Tianjin, China, and we believe that it makes a significant contribution to the literature.

PURPOSE

Vitamin D deficiency has been documented as a worldwide public health problem. To our knowledge, there has not been any large-scale study on vitamin D status in Tianjin, China. The aim of this study was to investigate vitamin D status among Tianjin residents and to determine influencing factors.

METHODS

This is a community-based study, and residents from both urban and rural areas of Tianjin were enrolled. Each participant completed a questionnaire regarding basic characteristics and lifestyle information. Serum 25-hydroxyvitamin D [25(OH)D] levels were statistically analyzed according to sex, age, and region. Other factors associated with vitamin D deficiency were also explored.

RESULTS

A total of 1814 participants were included, with mean serum 25(OH)D level of 49.44 ± 14.9 nmol/L; only 47.63% achieved the optimal (50-125 nmol/L) 25(OH)D level. Serum 25(OH)D levels were higher among male participants than among female participants (53.44 ± 13.94 versus 46.55 ± 14.91 nmol/L, P < 0.05) and among urban participants than among rural participants (50.4 ± 16.32 versus 48.65 ± 13.58 nmol/L, P < 0.05). Serum 25(OH)D levels were significantly higher among the age group of 40-49 years (50.7 ± 17.99 nmol/L) than among the ≥ 70 years (48.45 ± 14.49 nmol/L) or 18-29 years (47.81 ± 13.08 nmol/L) age groups.

CONCLUSIONS

There was a high prevalence of vitamin D deficiency/inadequacy among Tianjin residents, especially among female participants, rural young adults, and elderly individuals. Vitamin D supplementation is imperative for these high-risk vitamin D-deficient residents.

High Prevalence of Vitamin D Deficiency among Iranian Population: A Systematic Review and Meta-Analysis

BACKGROUND

The prevention and correction of vitamin D deficiency requires a precise depiction of the current situation and identification of risk factors in each region. The present study attempted to determine these entities using a systematic review and meta-analysis in Iran.

METHODS

Articles published online in Persian and English between 2000 and November 1, 2016, were reviewed. This was carried out using national databases such as SID, IranMedex, Magiran, and IranDoc and international databases such as PubMed, Google Scholar, and Scopus. The heterogeneity index among the studies was determined using the Cochran (Q) and I2 test. Based on the heterogeneity results, the random-effect model was applied to estimate the prevalence of vitamin D deficiency. In addition, meta-regression analysis was used to determine heterogeneity-suspected factors, and the Egger test was applied to identify publication bias.

RESULTS

The meta-analysis of 48 studies identified 18531 individuals with vitamin D deficiency. According to the random-effect model, the prevalence of vitamin D deficiency among male, female, and pregnant women was estimated to be 45.64% (95% CI: 29.63 to 61.65), 61.90% (95% CI: 48.85 to 74.96), and 60.45% (95% CI: 23.73 to 97.16), respectively. The results of the meta-regression analysis indicated that the prevalence of vitamin D deficiency was significantly different in various geographical regions (β=4.4; P=0.023).

CONCLUSION

The results obtained showed a significant prevalence of vitamin D deficiency among the Iranian population, a condition to be addressed by appropriate planning.

Prevalence of Osteoporosis in Peri- and Post-menopausal Women in Slum Area of Mumbai, India

Objective:

We conducted our study involving 1400 peri- and post-menopausal women who live in a slum area of Mumbai to determine the prevalence of osteoporosis, awareness about osteoporosis, education (knowledge regarding osteoporosis), treatment and prevention of osteoporosis.

Material and Methods:

A detailed medical, surgical, obstetrical & gynecological, menstrual, and drug history was recorded in a predesigned questionnaire designated for the study. Height and weight and body mass index were measured, physical activity level especially load bearing exercise was recorded, and amount of sunlight exposure per day was also recorded. Food intake was estimated using the 24 h dietary recall method and calcium and Vitamin D consumption pattern was assessed. We used calcaneum quantitative ultrasound to assess bone mineral density (BMD) for such large population.

Results:

The prevalence of low BMD was found in more than half of this population (81%). The mean age in Group I was found to be 36.50 ± 2.74 years as compared to 37.5 ± 3.44 years in Group II with low BMD, which was statistically significant (P = 0.02). The average age at menopause was 51.62 ± 5.72 years in Group I and 49.43 ± 4.52 years in Group II. The number of children and type of menopause has been found to be associated with low BMD in our study. Lack of physical exercise and low-calcium diet were significantly associated with low BMD.

Conclusion:

Our study showed that there is a high prevalence of Vitamin D deficiency and Osteoporosis even in adult women who live in a slum area. The findings from the study also suggest the need for large community-based studies so that high-risk population can be picked up early and early interventions and other lifestyle changes can be instituted so that no delay in implementing state and national or international health policy to tackle this increasing global health problem. The public awareness is important, and strategies to identify and manage low BMD in the primary care setting needs to be established and implemented.

The effect of parathyroid hormone on the uptake and retention of 25-hydroxyvitamin D in skeletal muscle cells

Data from our studies, and those of others, support the proposal that there is a role for skeletal muscle in the maintenance of vitamin D status. We demonstrated that skeletal muscle is able to internalise extracellular vitamin D binding protein, which then binds to actin in the cytoplasm, to provide high affinity binding sites which accumulate 25-hydroxyvitamin D₃ (25(OH)D₃) [1]. This study investigated the concentration- and time-dependent effects of parathyroid hormone (PTH) on the capacity of muscle cells to take up and release ³H-25(OH)D₃. Uptake and retention studies for ³H-25(OH)D₃ were carried out with C2C12 cells differentiated into myotubes and with primary mouse muscle fibers as described [1]. The presence of PTH receptors on mouse muscle fibers was demonstrated by immunohistochemistry and PTH receptors were detected in differentiated myotubes, but not myoblasts, and on muscle fibers by Western blot. Addition of low concentrations of vitamin D binding protein to the incubation media did not alter uptake of 25(OH)D₃. Pre-incubation of C2 myotubes or primary mouse muscle fibers with PTH (0.1 to 100 pM) for 3h resulted in a concentration-dependent decrease in 25(OH)D₃ uptake after 4 or 16h. These effects were significant at 0.1 or 1pM PTH (p<0.001) and plateaued at 10pM, with 25(OH)D₃ uptake reduced by over 60% (p<0.001) in both cell types. In C2 myotubes, retention of 25(OH)D₃ was decreased after addition of PTH (0.1 to 100pM) in a concentration-dependent manner by up to 80% (p<0.001) compared to non-PTH treated-C2 myotubes. These data show that muscle uptake and retention of 25(OH)D₃ are modulated by PTH, a physiological regulator of mineral homeostasis, but the cell culture model may not be a comprehensive reflection of vitamin D homeostatic mechanisms in whole animals.

Effect of Low-Dose Vitamin D Supplementation on Serum 25(OH)D in School Children and White-Collar Workers

OBJECTIVE

Our study aimed to investigate the nutritional vitamin D status of school children aged 9-15 years and white-collar workers in Zhejiang province, and evaluate the efficacy of low-dose-oral vitamin D supplementation in both populations.

METHODS

We conducted a prospective controlled trial during March 2014 to November 2015, comparing the efficacy of vitamin D supplements (400 IU/day) with non-intervention for 18 months in school children aged 9-15 years. Meanwhile, a before-after study was conducted among white-collar workers for 1 year. Serum 25(OH)D concentration was measured at baseline and after vitamin D supplementation, respectively.

RESULTS

At the baseline, 95% of school children and 84% of adult participants had vitamin D deficiency (<20 ng/mL). In school children, no difference was observed between the intervention and control groups with regard to anthropometric data. Serum 25(OH)D concentrations of the school children intervention group, school children control group and white-collar workers were 12.77 ± 3.01 ng/mL, 14.17 ± 3.59 ng/mL and 16.58 ± 3.66 ng/mL at baseline and increased to 17.34 ± 3.78 ng/mL, 18.04 ± 4.01 ng/mL and 17.75 ± 5.36 ng/mL after vitamin D supplementation, respectively. Although, after adjusting for potential confounders, the 400 IU oral vitamin D supplementation increased serum 25(OH)D concentration in school children (β = 0.81, p = 0.0426) as well as in white-collar workers (p = 0.0839), the prevalence of vitamin D deficiency was still very high among school children (79.23% in intervention group and 72.38% in control group) and white-collar workers (76.00%).

CONCLUSIONS

High prevalence of vitamin D deficiency was common in these two study populations. Daily doses of 400 IU oral vitamin D supplementation was not able to adequately increase serum 25(OH)D concentrations. A suitable recommendation regarding the level of vitamin D supplementation is required for this Chinese population.

25-hydroxyvitamin D is differentially associated with calcium intakes of Northern, Central, and Southern European adolescents: Results from the HELENA study

OBJECTIVES

Adolescents in the European Union (EU) exhibit a higher prevalence of vitamin D (VitD) deficiency than other age groups. The degree to which sunlight exposure 25-hydroxyvitamin D [25(OH)D] concentrations depends on a variety of factors, including diet. Nevertheless, the relationship between calcium and VitD intake and 25(OH)D concentrations has not been previously studied among adolescents living in different EU countries and consequently in different latitudes. Therefore, the aim of this study was to examine whether calcium and VitD intakes are differentially associated with 25(OH)D in adolescents from northern, central and southern EU countries.

METHODS

The present analysis included 178 adolescents from northern EU countries, 251 from central EU countries, and 212 from southern EU countries (ages 12.5-17.5 y). Mixed model linear regression analyses stratified by geographic location were used to verify associations between calcium and VitD intake and 25(OH)D concentrations. Age, Tanner stage, seasonality, energy intake, and supplement use were entered as covariates.

RESULTS

Only the calcium intake of central EU adolescents was positively associated with 25(OH)D (α = 0.005; 95% confidence interval, 0.007-0.028).

CONCLUSIONS

Further longitudinal studies should confirm these observations, as this could be important for future public health interventions aiming to increase 25(OH)D concentrations in adolescents.

Nutrient Status of Vitamin D among Chinese Children

Background: Vitamin D deficiency is considered to be a public health problem. However, the nutrient status of vitamin D in Chinese children is unclear. The aim of this study was to describe the vitamin D status among children aged under 18 years in southeast China. Methods: Children who visited the Huzhou Maternal and Child Care Hospital from January 2012 to August 2015 were included in this large cross-sectional study. Serum 25-hydroxyvitamin D (25(OH)D) concentrations were measured by electrochemiluminescence immunoassay. Vitamin D status was defined as deficiency (25(OH)D < 20 ng/mL), insufficiency (25(OH)D: 20–29 ng/mL) and sufficiency (25(OH)D ≥ 30 ng/mL). The association between relevant variables and vitamin D status was analyzed by a using generalized estimated equation model and a multivariate regression model. Results: 13,997 children aged under 18 years were included. Of these, 23.3% children suffered from low vitamin D status (deficiency and insufficiency), while 76.7% had a sufficient vitamin D status. The prevalence of low vitamin D status was 29.7% in winter and 23.4% in spring, which was higher than that in summer (21.4%) and autumn (19.9%). Clinical visiting children (32.1%) suffered more from low vitamin D than health examination children (17.6%). Additionally, age and season were independently and significantly associated with 25(OH)D concentrations, respectively. Conclusions: The deficiency and insufficiency status of vitamin D was very common among newborns and children aged one to 17 years. This indicates that more sunshine and vitamin D–fortified foods are necessary among Chinese children.

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

BACKGROUND

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

OBJECTIVES

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

SEARCH METHODS

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

SELECTION CRITERIA

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

DATA COLLECTION AND ANALYSIS

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

MAIN RESULTS

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

AUTHORS' CONCLUSIONS

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

Vitamin D deficiency in Malaysian adolescents aged 13 years: findings from the Malaysian Health and Adolescents Longitudinal Research Team study (MyHeARTs)

OBJECTIVE

To determine the prevalence of vitamin D deficiency (<37.5 nmol/L) among young adolescents in Malaysia and its association with demographic characteristics, anthropometric measures and physical activity.

DESIGN

This is a cross-sectional study among Form 1 (year 7) students from 15 schools selected using a stratified random sampling design. Information regarding sociodemographic characteristics, clinical data and environmental factors was collected and blood samples were taken for total vitamin D. Descriptive and multivariable logistic regression was performed on the data.

SETTING

National secondary schools in Peninsular Malaysia.

PARTICIPANTS

1361 students (mean age 12.9±0.3 years) (61.4% girls) completed the consent forms and participated in this study. Students with a chronic health condition and/or who could not understand the questionnaires due to lack of literacy were excluded.

MAIN OUTCOME MEASURES

Vitamin D status was determined through measurement of sera 25-hydroxyvitamin D (25(OH)D). Body mass index (BMI) was classified according to International Obesity Task Force (IOTF) criteria. Self-reported physical activity levels were assessed using the validated Malay version of the Physical Activity Questionnaire for Older Children (PAQ-C).

RESULTS

Deficiency in vitamin D was seen in 78.9% of the participants. The deficiency was significantly higher in girls (92.6%, p<0.001), Indian adolescents (88.6%, p<0.001) and urban-living adolescents (88.8%, p<0.001). Females (OR=8.98; 95% CI 6.48 to 12.45), adolescents with wider waist circumference (OR=2.64; 95% CI 1.65 to 4.25) and in urban areas had higher risks (OR=3.57; 95% CI 2.54 to 5.02) of being vitamin D deficient.

CONCLUSIONS

The study shows a high prevalence of vitamin D deficiency among young adolescents. Main risk factors are gender, ethnicity, place of residence and obesity.

Association between vitamin D status and serum parathyroid hormone concentration and calcaneal stiffness in Japanese adolescents: sex differences in susceptibility to vitamin D deficiency

There is currently insufficient information on serum 25-hydroxyvitamin D (25OHD) and parathyroid hormone (PTH) concentrations, and bone mineral status in healthy adolescents to allow reference values to be set. This study aimed to provide comparable data on vitamin D status in Japanese adolescents and to assess sex differences in susceptibility to vitamin D insufficiency. Serum 25OHD and PTH concentrations were measured in 1,380 healthy adolescents (aged 12-18 years). Subjects completed a questionnaire on exercise history, diet, and lifestyle factors. Calcaneal stiffness was evaluated by quantitative ultrasound. Serum 25OHD concentrations in boys and girls were 60.8 ± 18.3 and 52.8 ± 17.0 nmol/L, respectively. Approximately 30 % of boys and 47 % of girls had suboptimal 25OHD concentrations (<50 nmol/L). Serum PTH concentration was negatively correlated with serum 25OHD concentration in boys, but negatively correlated with calcium intake rather than serum 25OHD in girls. In contrast, the increment in calcaneal stiffness as a result of elevation of serum 25OHD was higher in girls than in boys. As vitamin D deficiency is common in Japanese adolescents, it was estimated that intakes of ≥12 and ≥14 μg/day vitamin D would be required to reach 25OHD concentrations of 50 nmol/L in boys and girls, respectively. Moreover, the results of the present study indicate that vitamin D deficiency has a greater association with calcaneal stiffness in girls than in boys.

Low Vitamin D Levels in Children with Fractures: a Comparative Cohort Study

BACKGROUND

The currently accepted ranges for "normal" serum vitamin D have recently been challenged in adults on the basis that healthy bone metabolism requires higher levels of vitamin D than previously thought.

PURPOSE

The purpose of this study was to evaluate whether a new "biologically based" classification based on 25(OH)vitamin D levels that invoke an endocrine biomarker response (<20 ng/mL for deficiency and <32 ng/mL for insufficiency) is more appropriate for children with fractures than historical criteria.

METHODS

Serum 25(OH)vitamin D levels were collected from 58 children with acute low-energy fractures from an outpatient orthopedic clinic from 2009 to 2012. These vitamin D levels were compared with a cohort of 103 children with chronic kidney disease (CKD) from an adjacent clinic, a condition with acknowledged low levels of vitamin D. Then, the prevalence of vitamin D sufficiency in the fracture cohort was evaluated and compared using both historical guidelines and newer biologically based criteria.

RESULTS

25(OH)vitamin D levels in the fracture cohort did not differ from levels in the CKD cohort (27.5 vs. 24.6 ng/mL) indicating a similar distribution of vitamin D levels. This finding was consistent when controlling for significant covariables using linear regression analyses. In the fracture cohort, there was a discrepancy between historical and biologically based criteria in 64% of children.

CONCLUSIONS

The results of the current study suggest that fracture patients are more frequently vitamin D deficient than previously thought. This finding is more readily apparent when newer biologically based criteria for vitamin D sufficiency are used.

High prevalence of vitamin D deficiency in urban health checkup population

BACKGROUND

Vitamin D deficiency is documented as a common health problem in the world. Limited data has been found on the prevalence of vitamin D deficiency in Beijing area.

AIM

To investigate the prevalence s of vitamin D deficiency in urban Beijing residents and the seasonal and monthly serum 25(OH)D variation in this population.

METHODS

This is an urban hospital based cross-sectional study lasting whole 2 years. 5531 (5-101 years old) urban Beijing residents for health checkup are recruited from December 9th, 2011 to December 8th, 2013. Each subject completed a questionnaire designed to quantify intake of vitamin D through food, vitamin D supplements, hours of sun exposure, sunscreen use over the past month. Serum 25(OH)D is statistically analyzed in accordance with gender, age, and time-lines.

RESULTS

Vitamin D deficiency (Serum 25(OH)D level ≤20 ng/mL) and sever deficiency (Serum 25(OH)D level ≤ 10 ng/mL) are highly prevalent in this population. The prevalence of vitamin D deficiency is 87.1% and higher prevalence is found in female (89.0%) than male (84.9% P < 0.001). Severe vitamin D deficiency is also higher in female than male (59.3% and 42.7%, respectively, P < 0.001). Female under 20 and over 80 have lower 25(OH)D levels compared to 40-60 years old female (both P < 0.05). Severe vitamin D deficiency are also highly prevalence in this two group (60.9% and 54.1%) compared with 40-60 years old females (43.1%, both P < 0.05). Seasonal variation are also found in this population (P < 0.01). Autumn and summer have the higher 25(OH)D level than winter and spring in both genders (P < 0.001). Winter and spring have higher vitamin D deficiency and Severe deficiency than the other two seasons (P < 0.05). Serum 25(OH)D level peaks in October and troughed in April in both female and male. Lower serum 25(OH)D level are found in April than February (P < 0.05) in both gender.

CONCLUSIONS

This is the first time to examine the prevalence of vitamin D deficiency among urban Beijing residents spanning the age spectrum. And Vitamin D deficiency and severe deficiency is found highly prevalent in this population, especially among females under 20 and older than 80 and in winter and spring seasons. Targeted prevention on vitamin D deficiency is urgent for this population.

Vitamin D Deficiency in Children and Adolescents in Bağcılar, İstanbul

OBJECTIVE

This study aimed to evaluate the frequency of seasonal 25-hydroxyvitamin D [25(OH)D] deficiency and insufficiency in children and adolescents living in Bağcılar, district of İstanbul city.

METHODS

Serum vitamin D levels of 280 children aged 3-17 years old were measured at the end of winter and at the end of summer. Of the total group, vitamin D levels were re-measured in 198 subjects. Vitamin D deficiency was defined as a serum 25(OH)D level less than 15 ng/mL and insufficiency-as levels between 15 and 20 ng/mL. Patients whose vitamin D levels were less than 15 ng/mL at the end of winter were treated with 2000 units/day of vitamin D for 3 months.

RESULTS

In the "end of winter" samples, 25(OH)D deficiency was present in 80.36% of the subjects and insufficiency in 11.79%. In the "end of summer" samples, vitamin D deficiency was detected in 3.44% and insufficiency in 27.75%. Vitamin D levels in the "end of winter" samples were not significantly different between boys and girls, while "end of summer" levels were significantly lower in girls (p=0.015). Sunlight exposure was significantly higher in boys (p=0.011). The group with sufficient dairy product consumption had significantly higher vitamin D levels in both "end of summer" and "end of winter" samples. Limb pain was frequently reported in children with low vitamin D levels in the "end of winter" samples (p=0.001). Negative correlations were observed between vitamin D levels and season and also between vitamin D levels and age.

CONCLUSION

It is essential to provide supplemental vitamin D to children and adolescents to overcome the deficiency seen especially at the end of winter.

Lower serum 25 (OH) D concentrations in type 1 diabetes: A meta-analysis

OBJECTIVE

Vitamin D may have protective effects against type 1 diabetes (T1D). However, the results of current cross-sectional studies have been inconsistent. We aimed to examine the association of serum vitamin D and T1D by conducting a meta-analysis.

METHODS

Multiple databases were searched until April 2014 to identify relevant studies. The search term was "serum vitamin D" and "type 1 diabetes". Random effects model was used to calculate the pooled risk estimate. The data were accessed by software Review manager 5.2.

RESULTS

We included a total of 23 studies (11 studies with 1900 participants of children or adolescents and 13 studies with 3494 participants of adults) in our meta-analysis. In children or adolescents, serum 25(OH) D in T1D was 5.69 ng/ml [95% confidence interval (CI) (2.82-8.55, P<0.0001) lower than in healthy controls. In adults, serum 25(OH) D in T1D was 2.61 ng/ml [95% confidence interval (CI) (1.13-4.09, P=0.0005) lower than in healthy controls. We did not find evidence of publication bias.

CONCLUSION

Serum 25OHD is significantly lower in patients with T1D than in healthy controls.

Low maternal vitamin D status during the second trimester of pregnancy: a cross-sectional study in Wuxi, China

BACKGROUND

Vitamin D deficiency is common in pregnant women, but an optimal serum vitamin D level during pregnancy has not been determined and remains an area of active research. Vitamin D data from large populations of pregnant Chinese women are still limited.

OBJECTIVE

To evaluate the vitamin D status of women in Eastern China during the second trimester of pregnancy.

METHODS

A hospital-based, cross-sectional, observational study. Serum 25-hydroxyvitamin D [25(OH)D] concentration was measured in samples from 5823 pregnant women in Wuxi City, China (latitude: 31.5o N), from January 2011 to June 2012.

RESULTS

The median serum 25(OH)D concentration was 34.0 nmol/L [2.5 nmol/L 25(OH)D = 1 ng/mL 25(OH)D]. Vitamin D deficiency [defined as 25(OH)D < 30 nmol/L according to the Institute of Medicine (National Academy of Sciences, Washington, D.C., USA)] or inadequacy [25(OH)D of 30-49.9 nmol/L] was identified in 40.7% and 38.0% of the women, respectively. Only 0.9% had a 25(OH)D level ≥ 80.0 nmol/L, which is the concentration recommended as adequate by the Endocrine Society (Washington, D.C., USA). Compared with older women, younger women were more likely to be deficient in vitamin D. There were significant differences in the 25(OH)D levels according to season. The 25(OH)D levels reached peak values in September and were correlated with (r = 0.337, P < 0.001), and fluctuated with, average monthly air temperatures.

CONCLUSIONS

There is a high prevalence of Vitamin D deficiency among pregnant Chinese women, and 25(OH)D levels varied according to season and air temperature. The results of this study also suggest that currently there is a big gap between the levels of Vitamin D detected in pregnant Chinese women and the levels recommended by the Endocrine Society.

[Determination of 25(OH)D serum levels in children with systemic lupus erythematosus and juvenile idiopathic arthritis]

BACKGROUND

It is well recognized that vitamin D has a direct effect in bone and muscle and has been associated as well with some rheumatologic diseases. Reports in children are scarce. The aim of this study was to determine the concentration level of 25(OH)D in a group of patients with systemic lupus erythematosus (SLE) and juvenile idiopathic arthritis (JIA) and compare them with healthy controls.

METHODS

Vitamin D (25(OH)D) was measured with isotope-dilution liquid chromatography-tandem mass spectrometry (ID-LC-MS/MS), PTH with immunoradiometric assay (IRMA), calcium, phosphorus and alkaline phosphatase by colorimetric assay in 37 patients with SLE, 37 patients with JIA and 79 healthy controls.

RESULTS

Mean 25(OH)D concentration levels were as follows: SLE 18.9±7.92ng/ml, JIA 21.97±5.55ng/ml and 23.6±3.07ng/ml in healthy controls. There was a significant difference between SLE patients vs. healthy controls (p <0.05); 29.7% of SLE patients, 35.1% of JIA patients and 31.6% of healthy controls had deficient levels of vitamin D.

CONCLUSIONS

One third of the total sample of children in this study had deficient levels of vitamin D. Patients with SLE presented a significant difference compared with healthy controls.

The phenomenon of micronutrient deficiency among children in China: a systematic review of the literature

OBJECTIVE

The present study aimed to review the literature on micronutrient deficiency and other factors influencing a deficiency status among children living in China.

DESIGN

A systematic review was performed to analyse the literature.

SETTING

Studies were identified through a search of PubMed and secondary references.

SUBJECTS

Children living in China aged less than 18 years.

RESULTS

Sixty-one articles were included. The prevalence of vitamin A deficiency decreased to approximately 10 % in 1995-2009. It increased with age but no significant difference was found between genders. The prevalence of thiamin and vitamin B12 deficiency was 10·5 % in Yunnan and 4·5 % in Chongqing provinces, respectively. Higher vitamin D deficiency rates were seen in spring and winter. The incidence of bleeding due to vitamin K deficiency was 3·3 % in 1998-2001 and more prevalent in rural areas. Both iodine deficiency and excess iodine intake were observed. Goitre rates were reported in Tibet, Jiangxi, Gansu and Hong Kong (3·5-46 %). Anaemia rates ranged from 20 % to 40 % in 2007-2011. High Se deficiency rates were found in Tibet, Shaanxi and Jiangsu. High Zn deficiency rates were also found (50-70 %) in 1995-2006. Few studies reported Ca deficiency rates (19·6-34·3 %). The degrees of deficiency for vitamin A, vitamin B12, Fe and Zn were more substantial in rural areas compared with urban areas.

CONCLUSIONS

The prevalence of micronutrient deficiency rates varied. Socio-economic status, environmental factors and the Chinese diet may influence micronutrient deficiency. Public health policies should consider implementing programmes of supplementation, food fortification and nutrition education to address these deficiencies among Chinese children.

Seasonal vitamin D status of healthy schoolchildren and predictors of low vitamin D status

OBJECTIVES

The aim of the study was to assess seasonal prevalence of vitamin D deficiency according to sex and to determine the relations between serum levels of 25-hydroxyvitamin D [25(OH)D] and parathyroid hormone (PTH) and sociodemographic characteristics in otherwise healthy schoolchildren during spring and autumn.

METHODS

In a cross-sectional study, 746 healthy students aged between 11 and 18 years were recruited during spring (n = 375) and autumn (n = 371). Sociodemographic data were collected by a questionnaire. Serum 25(OH)D, PTH, calcium, phosphate, and alkaline phosphatase were measured. Serum 25(OH)D levels were categorized as <50 nmol/L (vitamin D deficiency) and <25 nmol/L (severe deficiency).

RESULTS

Mean ± standard deviation 25(OH)D levels were 22.3 ± 10.5 nmol/L in girls and 28.5 ± 17.0 nmol/L in boys during spring (P < 0.001) and 36.5 ± 20.3 nmol/L in girls and 45.0 ± 18.5 nmol/L in boys during autumn (P < 0.001). The prevalence of vitamin D deficiency was 93% during spring and 71% during autumn. There was a negative correlation between 25(OH)D and PTH levels (P < 0.01). We determined a cutoff point of serum 25(OH)D in which the mean serum PTH concentration began to increase as 35.8 nmol/L (P < 0.0001). The age, sex, and calcium level were found to be independent predictors for vitamin D deficiency.

CONCLUSIONS

Vitamin D deficiency is prevalent among healthy schoolchildren. It is noteworthy that 25(OH)D levels were significantly lower in girls and during autumn. We recommend vitamin D supplementation for children in addition to more time spent for outdoor activities for sensible sunlight exposure.

Vitamin D status and its relationship with metabolic syndrome risk factors among adolescent girls in Boukan, Iran

OBJECTIVE

To investigate vitamin D status and its association with components of the metabolic syndrome (MetS) in adolescent girls attending high school in Boukan, Iran during winter 2012.

DESIGN

A cross-sectional study.

SETTING

High schools of Boukan city, Iran.

SUBJECTS

A sample of 216 girls aged 14-17 years was selected by multistage random sampling from four districts of Boukan. Weight, height, waist circumference, blood pressure, daily energy intake, physical activity and serum 25-hydroxyvitamin D (25(OH)D), fasting blood glucose, TAG and HDL-cholesterol levels of all participants were evaluated. Serum 25(OH)D level <20 ng/ml was defined as vitamin D deficiency.

RESULTS

Mean serum 25(OH)D was 7.26 (sd 2.81) ng/ml and 96 % of the participants had vitamin D deficiency. According to age-modified definitions of the National Cholesterol Education Program Adult Treatment Panel III, MetS was diagnosed in 10.6% of the participants. In multivariable regression analysis after adjustment for BMI, energy intake and physical activity level, serum 25(OH)D was inversely associated with fasting blood glucose (β = -0.143, P = 0.04). No significant relationship was found between serum 25(OH)D and other components of MetS.

CONCLUSIONS

The high prevalence of vitamin D deficiency warrants national polices and interventions towards improving this major health problem among adolescent girls. Low 25(OH)D level was significantly associated with increased fasting blood glucose. Prospective studies are needed to determine the effects of vitamin D deficiency on the development of MetS and related metabolic diseases in adolescent girls.

Analysis of 25(OH)D serum concentrations of hospitalized elderly patients in the Shanghai area

OBJECTIVE

To find an association between basic characteristics, seasons as well as disease types and 25-Hydroxyvitamin D serum concentrations in Chinese patients.

METHODS

We randomly selected 5470 Chinese patients with various diseases, who were hospitalized between May 2012 and August 2013 in Shanghai and analyzed their serum 25-Hydroxyvitamin D2 (25 (OH)D2) and 25-Hydroxyvitamin D3 (25(OH)D3) concentrations with liquid chromatography-tandem mass spectrometry (LC-MS/MS) as well as their parathyroid hormone (PTH) and serum creatinine blood levels. The resulting data were analyzed by linear regression and variance analyses or multivariate analysis with covariance.

RESULTS

The 25(OH)D serum concentrations were lowest in December. Among the subjects with a median age of 83.0 ± 16.0, the median 25(OH)D2, 25(OH)D3 and total 25(OH)D serum concentrations were 1.00 ± 1.80 ng/ml, 12.20 ± 8.50 ng/ml and 14.80 ± 9.80 respectively, indicating a prevalent 25(OH)D deficiency. According to our multivariate analysis of covariance, the factors affecting 25(OH)D2 and 25(OH)D3 serum concentrations included age, creatinine, PTH, season and type of disease, whereas gender correlated only with 25(OH)D2 and 25(OH)D2 and D3 values correlated negatively with each other. Our results further revealed that 25(OH)D3 levels were low while 25(OH)D2 levels were high among patients with lung diseases, dyskinesia and coronary heart diseases. In addition, participants with diabetes and cerebral infarction had higher 25(OH)D3 serum concentrations compared with lung disease patients.

CONCLUSION

Vitamin D intake particularly during winter and summer seasons is important especially for elderly lung disease, dyskinesia and coronary heart disease patients to improve their quality of life.

Prevalence of 25-hydroxyvitamin D deficiency in Korean adolescents: association with age, season and parental vitamin D status

OBJECTIVE

We aimed to assess the prevalence and associated factors of vitamin D deficiency in healthy adolescents and to determine parent-adolescent association in vitamin D status.

DESIGN

A cross-sectional study.

SETTING

Data from the Korean National Health and Nutrition Examination Survey (KNHANES) 2008-2009. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using 125I-labelled RIA kits. Vitamin D deficiency in adolescents was defined as 25(OH)D level <27·5 nmol/l, and 25(OH)D levels between 27·5 and <50 nmol/l were considered insufficient. For the parents, vitamin D deficiency was defined as 25(OH)D level <50 nmol/l.

SUBJECTS

The study population consisted of 2062 adolescents (1095 boys, 967 girls; aged 10-18 years) and their parents (1005 fathers, 1341 mothers).

RESULTS

Overall, 13·4% of adolescents (boys 11·7%, girls 15·4%) were 25(OH)D deficient, 54·7% were 25(OH)D insufficient. Prevalence of vitamin D deficiency increased with age (P < 0·0001). Parental vitamin D deficiency was more prevalent in vitamin D-deficient adolescents than in non-deficient adolescents (all P < 0·0001). In multivariate logistic regression analyses, predictors for vitamin D deficiency were senior high school students (OR = 3·45-4·33), winter/spring season (OR = 3·18-5·11/5·35-7·36) and parental vitamin D deficiency (OR = 1·78-4·88; all P < 0·05).

CONCLUSIONS

Vitamin D insufficiency is prevalent among healthy Korean adolescents and the parent-offspring association warrants vitamin D screening for family members of deficient individuals.

Evidence for a specific uptake and retention mechanism for 25-hydroxyvitamin D (25OHD) in skeletal muscle cells

Little is known about the mechanism for the prolonged residence time of 25-hydroxyvitamin D (25OHD) in blood. Several lines of evidence led us to propose that skeletal muscle could function as the site of an extravascular pool of 25OHD. In vitro studies investigated the capacity of differentiated C2 murine muscle cells to take up and release 25OHD, in comparison with other cell types and the involvement of the membrane protein megalin in these mechanisms. When C2 cells are differentiated into myotubes, the time-dependent uptake of labeled 25OHD is 2-3 times higher than in undifferentiated myoblasts or nonmuscle osteoblastic MG63 cells (P < .001). During in vitro release experiments (after 25OHD uptake), myotubes released only 32% ± 6% stored 25OHD after 4 hours, whereas this figure was 60% ± 2% for osteoblasts (P < .01). Using immunofluorescence, C2 myotubes and primary rat muscle fibers were, for the first time, shown to express megalin and cubilin, endocytotic receptors for the vitamin D binding protein (DBP), which binds nearly all 25OHD in the blood. DBP has a high affinity for actin in skeletal muscle. A time-dependent uptake of Alexafluor-488-labeled DBP into mature muscle cells was observed by confocal microscopy. Incubation of C2 myotubes (for 24 hours) with receptor-associated protein, a megalin inhibitor, led to a 40% decrease in 25OHD uptake (P < .01). These data support the proposal that 25OHD, after uptake into mature muscle cells, is held there by DBP, which has been internalized via membrane megalin and is retained by binding to actin.

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.

Impact of vitamin D fortified milk supplementation on vitamin D status of healthy school children aged 10-14 years

Vitamin D deficiency is a major public health problem, needing immediate attention. We studied the effect of vitamin D fortification of milk in school children. Our results show that fortification of milk is safe and effective strategy to deal with widespread vitamin D deficiency.

INTRODUCTION

Vitamin D deficiency among school children and adolescents is a well-documented major public health problem, needing immediate attention. To assess the effect of vitamin D fortified milk on serum 25 hydroxy vitamin D [S.25(OH)D] levels, we carried out a prospective double-blind randomized control trial in apparently healthy school children, aged 10-14 years.

METHODS

Of 776 subjects recruited out of 796 who consented, 713 (boys-300; girls-413) completed the study. Subjects were randomized into three groups. Group A (n = 237) received 200 ml of unfortified milk per day while group B (n = 243) and group C (n = 233) received 200 ml of milk fortified with 600 IU (15 μg) and 1,000 IU (25 μg) of vitamin D per day for 12 weeks. Serum calcium, phosphate, alkaline phosphatase, S.25(OH)D, and urinary calcium/creatinine ratio were estimated at baseline and after supplementation.

RESULTS

Hypovitaminosis D [25(OH)D < 20 ng/ml] was observed in 92.3 % subjects with mean S.25(OH)D level of 11.69 ± 5.36 ng/ml. There was no significant difference in S.25(OH)D levels among the three groups at baseline. The mean percentage change in S.25(OH)D level in groups B (137.97 %) and C (177.29 %.) were significantly greater than group A (-5.25 %). The percentage of subjects having S.25(OH)D levels >20 ng/ml following supplementation were 5.9 % in group A, 69.95 % in group B, and 81.11 % in group C in comparison to 6.32 %, 4.9 % and 12 %, respectively, at baseline.

CONCLUSION

Fortification of milk with vitamin D is an effective and safe strategy in improving S.25(OH)D levels in children aged 10-14 years.

Evaluation of two automated immunoassays for 25-OH vitamin D: comparison against LC-MS/MS

BACKGROUND/METHODS

A total of 95 human serum specimens, and a 12 specimen precision panel, were measured by 2 automated immunoassays (investigation use only DiaSorin LIAISON(®) 25 OH Vitamin D TOTAL Assay [LSN], and Siemens ADVIA Centaur(®) Vitamin D Total (VitD) assay [Centaur]) and the results compared against LC-MS/MS [LCMS] used as the reference method (Esoterix Inc.). For functional sensitivity and precision, 12 serum specimens [range 1.2-148ng/mL] were run in six replicates [N=30] or four replicates [N=20], respectively, for 5 consecutive days.

RESULTS

Passing-Bablok fit and Difference plot analysis [N=92] showed that although both immunoassays had comparable correlation coefficient [r] values to LCMS (0.936 and 0.933), the LSN assay results were statistically equivalent to those given by LCMS (slope 0.93, intercept -2.5), whereas the results of the Centaur assay showed overall significant assay bias compared to LCMS (slope 1.30, intercept -15.8) and this bias was more significant for doses <30ng/mL by LCMS [bias -30.4%; 95% limits of agreement -72.4% to 11.7%]. For specificity, based on 25-OHD2 and 25-OHD3 levels assessed by LCMS, we divided the specimens into 2 groups, one with detectable 25-OHD2 [Group 1, N=41] and the other with no detectible 25OHD2 [Group 2, N=51]. The 2 groups showed comparable correlation coefficient [r] values between the methods, but showed significant differences in slope: Centaur [1.48 with group 1 and 1.18 with group 2] compared to LSN [0.91 with Group 1 and 0.96 with Group 2]. LSN demonstrated better precision [total CV range 5.5-10.0%] compared to Centaur [total CV range 11.0-16.3%]. Functional sensitivity was calculated per EP-17A: 2.15ng/mL by LSN and 4.57ng/mL by Centaur.

CONCLUSIONS

Though there was good overall correlation, substantial bias was present in Centaur. Although LSN had a slope and intercept that was not significantly different than LCMS, Centaur had a significantly higher slope in specimens containing measurable 25-OHD2 levels, a large negative intercept and a significant negative dose bias for doses <30ng/mL by LCMS, suggesting the Centaur assay would report a higher frequency of patients with apparent vitamin D insufficiency/deficiency at the low end and apparent vitamin D toxicity at the high end compared against LCMS. This article is part of a Special Issue entitled 'Vitamin D Workshop'.

Effect of vitamin D administration in vitamin D-deficient pregnant women on maternal and neonatal serum calcium and vitamin D concentrations: a randomised clinical trial

There are several studies in which a correlation between maternal vitamin D deficiency and serum mineral disorders in the mother and the newborn has been reported. The present randomised clinical trial was designed to investigate the effect of vitamin D administration on maternal and fetal Ca and vitamin D status. The trial was carried out on 160 pregnant women. Vitamin D-deficient (25-hydroxyvitamin D (25(OH)D) < 30 ng/ml) pregnant women were recruited at 26–28 weeks of pregnancy. In the control group, a multivitamin supplement containing 400 IU vitamin D3/d was given. Patients in the treatment group were treated with 50 000 IU vitamin D3 weekly for a total duration of 8 weeks. At delivery, maternal and fetal Ca and 25(OH)D levels in both groups were compared. In total, 81 % of pregnant women were vitamin D deficient. At the time of delivery, Ca and vitamin D levels were higher in the treatment group compared with the control group (92 (sd 3) v. 85 (sd 4) mg/l, respectively, P= 0·001 for serum Ca; 47·8 (sd 11·1) v. 15·9 (sd 6·6) ng/ml, respectively, P< 0·001 for vitamin D). At the time of delivery, 32·7 % of women in the control group had hypocalcaemia, while no hypocalcaemic case was detected in the vitamin D-treated group. Mean neonatal serum 25(OH)D was higher in the treatment group compared with the control group (27·7 (sd 5·2) v.10·9 (sd 4·4) ng/ml, respectively, P< 0·01). The neonatal Ca level in the treatment group was significantly higher than that of the control group (99 (sd 3) v. 91 (sd 3) mg/l, respectively, P< 0·001). The administration of vitamin D to pregnant women with vitamin D deficiency improves both maternal and neonatal Ca levels.

A glimpse of vitamin D status in Mainland China

As an essential dietary micronutrient, vitamin D plays a pivotal role in promoting calcium absorption in the intestine and maintaining a healthy skeletal system throughout life. Beyond bone health, an emerging volume of scientific studies shows that vitamin D also may provide cardiovascular, metabolic, and immunologic benefits and reduce mortality. To our knowledge, in mainland China no national surveys have been conducted to date to depict the overall vitamin D status in the population. Therefore, the purpose of this contribution was to provide the best possible evaluation of vitamin D deficiency/insufficiency in China by reviewing publications that measured plasma/serum 25-hydroxyvitamin-D (25[OH]D) levels in various age groups and in different areas of China from January 2000 to June 2012. From these investigations conducted throughout the country and from newborns to adults to the elderly, it has been found that vitamin D deficiency/insufficiency is prevalent in the Chinese population in almost all age groups and areas if individuals are not taking vitamin D-fortified products/supplements or are lacking sufficient sunshine exposure. Some studies showed severe deficiency (25[OH]D <25 nmol/L) in Nanjing (north latitude 31) during the winter months and in Beijing (north latitude 40) in the fall. This unoptimistic situation represents a significant but modifiable public health risk that deserves greater attention and more efficient and timely management.

Serum 25-hydroxyvitamin D concentration does not correlate with atopic dermatitis severity

BACKGROUND

An inverse correlation between serum 25-hydroxyvitamin D concentration and atopic dermatitis (AD) severity has been suggested.

OBJECTIVE

To determine if a statistically significant relationship exists between serum 25-hydroxyvitamin D concentration and AD severity.

METHODS

A cross-sectional study was conducted of patients with AD who were 1 to 18 years of age. An objective Severity Scoring of Atopic Dermatitis (SCORAD) and a serum 25-hydroxyvitamin D concentration were measured for each subject. Statistical analysis was performed using appropriate univariate tests and multivariable models.

RESULTS

Ninety-four of 97 enrolled subjects were included in the analysis. Vitamin D deficiency (25-hydroxyvitamin D <20 ng/mL) was present in 37 subjects (39%), insufficiency (25-hydroxyvitamin D 21-29 ng/mL) in 33 (35%), and sufficiency (25-hydroxyvitamin D ≥30 ng/mL) in 24 (26%). The correlation between 25-hydroxyvitamin D concentration and SCORAD was not significant (r = -0.001; P = .99). A multivariate model showed that a lower serum 25-hydroxyvitamin D concentration was significantly associated with age 3 years or older (P < .0001), black race (P < .0001), and winter season (P = .0084).

LIMITATIONS

Limitations of this study include the inability to control for natural sunlight exposure, vitamin D intake, and AD treatment; in addition, only a single time point was captured.

CONCLUSIONS

Serum 25-hydroxyvitamin D concentration is not significantly correlated with AD severity in our pediatric population.

Status of vitamin D in children with sickle cell disease living in Madrid, Spain

Patients with sickle cell disease have vitamin D deficiency and poor bone health which makes them prone to have an increased risk of fractures and osteoporosis in adulthood. We performed a prospective, cross-sectional study in children diagnosed with sickle cell disease living in Madrid, Spain. The purpose of this study was to evaluate the status of vitamin D of these children. Patients 0-16 years old were enrolled between 2008 and 2011. We studied demographics, calcium metabolism, and bone health, especially by measuring levels of 25-hydroxyvitamin D (25(OH)D), during different seasons of the year, and bone densitometry (beyond 4 years of age). Seventy-eight children were included in the study. Mean age was 4.8 ± 4.3 years, and mean serum 25(OH)D level was 21.50 ± 13.14 ng/ml, with no differences in 25(OH)D levels within different seasons. Fifty-six percent of children had levels of 25(OH) vitamin D of <20 ng/ml, whereas 79 and 18 % of them had levels of <30 and <11 ng/ml, respectively. Secondary hyperparathyroidism was observed in 25 % of children. Densitometry was performed in 33 children, and an abnormal z-score was seen in 15.2 % of them with no correlation with levels of 25(OH)D.

CONCLUSIONS

Vitamin D deficiency is highly prevalent in children with sickle cell disease, who are residing in Madrid, Spain, and it is detected at a young age. We propose that early intervention may increase the possibility of an adequate bone density later in life.

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.

Vitamin D status and associated factors in recent-onset type 1 diabetic children in Iran

Background

In this study, the prevalence of vitamin D deficiency was assessed in a group of children and adolescent patients with recent-onset type 1 diabetes mellitus (T1DM).

Methods

Fifty-three patients with age 8–18 years and duration of T1DM less than 8 weeks were recruited. A food frequency questionnaire (FFQ) was used to assess dietary vitamin D and calcium intake. Sunshine exposure was measured using a questionnaire to quantify the amount of time children spent in the sun and other sun-related habits, and a sun index score was generated. Serum 25(OH)D < 20 ng/ml was considered as vitamin D deficiency. Logistic regression was used to assess predictors of vitamin D deficiency.

Results

All patients were vitamin D deficient (77%) or insufficient (23%). In a logistic regression model, it was shown that the risk of being vitamin D deficient was significantly decreased by sunlight exposure ≥ 15 minutes during the weekends versus < 15 minutes (OR: 0.06, 95% CI: 0.01–0.75; P=0.029). In addition, vitamin D deficiency in boys was lower than girls in this model (OR: 0.164 [95% CI: 0.02–1.11]; P = 0.063).

Conclusion

Vitamin D deficiency is highly prevalent among children and adolescents with T1DM in Iran. Boys and children with ≥ 15 minutes sunlight exposure in weekends were less likely to be vitamin D deficient than girls and those with < 15 minutes sunlight exposure.

Prevalence and cut-off point of vitamin D deficiency among secondary students of Arak, Iran in 2010

INTRODUCTION

Vitamin D has a basic role in bone growth and metabolism and has been noticed for its important role in many diseases, such as diabetes, depression, hypertension, and cardiovascular disease. Regarding some studies, detection of vitamin D deficiency in different places has important implication for health. This study determined prevalence of vitamin D deficiency in Arak, a centrally located city in Iran.

MATERIALS AND METHODS

Based upon a cross-sectional study in 2010, 420 students 10--16 years old including 220 girls and 200 boys, studied at Arak secondary schools, were selected by a multistage sampling. The level of 25 (OH) D and PTH (parathormone) was measured and also the prevalence of vitamin D deficiency in different intensities was evaluated and compared between girls and boys by the Student t-test. Vitamin D deficiency for the students was categorized into three intensities based on three levels of 25 (OH) D: mild deficiency - 15 ≤ 25 (OH) D < 20 ng/ml, moderate deficiency -- 8 ≤ 25 (OH) < 15 ng/ml, severe deficiency - 25 (OH) <8 ng/ml. The relationship between the 25 (OH) D and PTH was assessed by Scatter chart to define cut-off points for vitamin D deficiency.

RESULTS

Based on 25 (OH) D < 20 ng/ml, 84% of the students had vitamin D deficiency including 60.7% mild, 22.4% moderate, and 0.7% severe. Three local cut-off points including 13, 21, and 33 ng/ml were defined in the Scatter chart. The results showed that the deficiency of vitamin D in girls is much more than that in boys (P = 0.05).

CONCLUSION

The high prevalence of vitamin D deficiency could be probably a result of different etiologies. We recommended that people should be encouraged to take vitamin D and calcium supplements and also they should have more exposure to the sunlight.

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 deficiency and calcium intake in reference to increased body mass index in children and adolescents

Vitamin D deficiency has been linked to several chronic diseases in adults. Studies focusing on children and adolescents, however, are limited. In this randomized cross-sectional study, we aimed to determine the prevalence of vitamin D deficiency and its relationship with childhood obesity and dietary calcium intake among a population of healthy urban Saudi children and adolescents. To achieve this, 331 randomly selected Saudi children (53.8% females and 46.2% males) aged 6-17 years were included. Demographic, medical, and dietary information were collected; anthropometrics were measured. Levels of serum fasting glucose, lipid profile, 25(OH) D, and for albumin corrected calcium were analyzed. Vitamin D deficiency was noted in all subjects, with girls having significantly lower vitamin D levels than boys. Mean calcium intake was found to be 60% of the required dietary allowance (RDA), while the mean vitamin D intake was 23% of RDA. Vitamin D status and calcium intake were comparable in both normal and overweight/obese children and adolescents. Vitamin D status was highest among children who had calcium intake >800 mg/day. In adolescents there was insignificant but decreasing trend in BMI, which was observed to be highest among those whose calcium intake was <250 mg/day and lowest among those taking >800 mg/day.

CONCLUSION

results from this study suggest the importance of vitamin D fortification and increased dietary calcium in the Saudi diet to meet RDA requirements and avoid onset of vitamin D deficiency-related diseases in Saudi children and adolescents.

Prevalence and risk factors for vitamin D deficiency in children with iron deficiency anemia

PURPOSE

The increasing prevalence of breast feeding has led to concerns about vitamin D deficiency (VDD) and iron deficiency anemia (IDA) in children. We evaluated the prevalence of VDD in a population of Korean children with IDA and assessed the risk factors for VDD in these children.

METHODS

A total of 79 children who were diagnosed with IDA were prospectively surveyed from April 2010 to March 2011. Data were collected by questionnaire, medical assessment, and laboratory tests, including measurement of 25-hydroxyvitamin D (25OHD), hemoglobin, and wrist radiography.

RESULTS

The median age was 22 months and 30% of the subjects were female. Over a half of subjects (58%) had subnormal vitamin D level (25OHD<30 ng/mL), and VDD (25OHD<20 ng/mL) was present in 39% of children. There was no difference in serum hemoglobin level between IDA patients with VDD and those without VDD. Most subjects (89%) were currently or had recently been breastfed and almost all subjects (97%) who had VDD received breastfeeding. Children with VDD were more likely to be younger than 2 years, to have been breastfed, and to have been tested in winter or spring. Multivariable analysis indicated seasonal variation was a significant independent risk factor for VDD in our IDA patients.

CONCLUSION

Our results demonstrated that VDD has a high prevalence in Korean children with IDA. Primary care physicians should be aware of the possibility of VDD in children with IDA and should supplement the vitamin D as well as iron.