Vitamin D status among infants, children, and adolescents in southeastern China

The Association between Serum Vitamin D Levels and Urinary Tract Infection Risk in Children: A Systematic Review and Meta-Analysis

The association between serum vitamin D levels and urinary tract infection (UTI) in children is unclear. We undertook a systematic review and meta-analysis to evaluate the relationships between different vitamin D levels and the likelihood of UTI in children. Online databases, including Web of Science, PubMed, Embase, and Cochrane Library, were searched up to 6 February 2023 for studies based on the inclusion criteria. Weighted mean difference (WMD) and Odds Ratios (ORs), along with their 95% confidence intervals (CI), were calculated, and the random-effects model was used for analysis. Twelve case-control studies and one cross-sectional study (839 children with UTI and 929 controls) were included. We found that children with UTI had lower levels of serum vitamin D than healthy controls (WMD: -7.730, 95% CI: -11.57, -3.89; p < 0.001). Low vitamin D levels were significantly associated with UTI in children (OR: 2.80; 95% CI: 1.55, 5.05; p = 0.001). The likelihood of children having a UTI significantly increased when their serum vitamin D level was less than 20 ng/mL (OR: 5.49, 95% CI: 1.12, 27.04; p = 0.036). Therefore, vitamin D level, especially when less than 20 ng/mL, is a risk factor in UTI.

Vitamin D status in children and its association with glucose metabolism in northern China: a combination of a cross-sectional and retrospective study

OBJECTIVES

This study aimed to explore the vitamin D status of children in northern China and the association between vitamin D and glucose metabolism.

DESIGN

Cross-sectional study was conducted among child participants and retrospective study designs were conducted among adult participants.

SETTING AND PARTICIPANTS

Both studies were recruited from Harbin, 326 children were included in children's study, 8469 adults were included in adult study.

PRIMARY AND SECONDARY OUTCOME MEASURES

Physical examination, lifestyle and dietary habit data were recorded in all the participants. Serum insulin, glucose, 25(OH)D₃ concentrations in children and serum glucose and lipids levels in adults were measured. Rickets history was also investigated in adults, which was used to define vitamin D deficiency in childhood. The associations were tested by linear regression and binary logistic regression.

RESULT

In the children's study, only 10.7% of participants were vitamin D sufficient (≥30 ng/mL). Inverse correlations between serum 25(OH)D₃ concentration and fasting insulin and homeostasis model assessment - insulin resistance (HOMA-IR) were found, and children with lower serum 25(OH)D₃ concentrations were likely to have insulin resistance (IR) (OR: 0.955, 95% CI: 0.917 to 0.995, p value: 0.027). In an adult study, rickets in childhood increased the risk of type 2 diabetes in male participants (OR=1.414, 95% CI=1.013 to 1.972; p value=0.042), but this result was not observed in female participants.

CONCLUSION

Our findings suggest that vitamin D deficiency is widespread in northern China. Vitamin D deficiency in childhood was associated with IR and increased the risk of type 2 diabetes in male adults.

Vitamin D Status for Chinese Children and Adolescents in CNNHS 2016-2017

Vitamin D is very important in maintaining children's bone health because of its regulatory role in calcium and phosphate metabolism. To better understand vitamin D status and related risk factors of children and adolescents in China, this study analyzed the 25-hydroxyvitamin-D (25(OH)D) concentration of children and adolescents aged 6-17 years in China and assessed the risk factors of vitamin D deficiency and insufficiency. We analyzed the data of 25(OH)D concentration collected from the China National Nutrition and Health Survey of Children and Lactating Mothers in 2016-2017 (CNNHS 2016-2017). The age, sex, region type, ethnicities, season, weight and height were recorded, measured by unified questionnaire, equipment and standards. The concentration of 25(OH)D was detected by LC-MS/MS. A total of 64,391 participants from the cross-sectional study of CNNHS in 2016-2017 were included in this study. The median serum 25(OH)D concentration was 17.70 (13.20-22.68) ng/mL, 18.70 (14.10-23.80) ng/mL in boys and 16.60 (12.40-21.40) ng/mL in girls. The total prevalence rate of vitamin D deficiency and insufficiency was 65.98% when the cut-off was 20 ng/mL, 60.42% for boys and 71.99% for girls. According to the results of logistic regression analysis, girls aged above 12 y, living in midlands and northern regions, in spring and winter seasons and with abdominal obesity will have a significantly increased risk of vitamin D deficiency and insufficiency among Chinese children and adolescents. The results showed that vitamin D deficiency and insufficiency are very common among children and adolescents aged 6-17 y in China. They should be encouraged to have more effective sunlight exposure, increased intake of vitamin D from food or supplements in their diet, especially for those aged above 12 y, living in the northern or midlands areas, in spring and winter, and abdominally obese.

Correlation analysis between vitamin A, D, and E status with altitude, seasonal variation, and other factors, among children aged 0-6 years in a Chinese population living in the Tibetan plateau of Ganzi prefecture

Objective

We attempted to understand the status of vitamin (Vit) A, D, and E in children aged 0–6 living in the Tibetan plateau areas of Ganzi prefecture, to provide the basis for relevant government departments to carry out physical examinations of these children and to prevent and cure four key diseases (Infantile diarrhea, nutritional anemia, rickets, and infantile pneumonia).

Methods

Serum retinol and tocopherol levels were detected using high‐performance liquid chromatography (HPLC). Serum levels of 25‐(OH)D were detected by high‐performance liquid chromatography–tandem mass spectrometry (LC–MS). The polynomial logistic regression was used to analyze the effects of age, season, altitude, and gender on Vit A, D, and E levels.

Results

Vit A and D had the lowest mean serum levels before the age of 1 year and with the most significant deficiency rates. The lowest Vit E levels were seen in the Toddlerhood group. The rates of deficiency and insufficiency were the highest. Vit A, D, and E levels were significantly affected by seasonal changes and were significantly higher in the summer than in any other season. Vit A and D were significantly affected by altitude, and their levels were lowest above 4 km.

Conclusion

The overall levels of Vit A, D, and E in children aged 0–6 in the Tibetan plateau areas of Ganzi prefecture were lower than those in the plain's areas.

Multilevel Analysis of the Nutritional and Health Status among Children and Adolescents in Eastern China

We aimed to identify multiple nutritional health problems and the relevant factors among children and adolescents aged 7–17 years. This study was part of the China Nutrition and Health Surveillance of Children and Lactating Mothers in 2016–2017, conducted in Jiangsu Province in eastern China. After sampling, 3025 school-age children and adolescents were enrolled into this study. Demographic information collections and anthropometric measurements were conducted by trained local Center for Disease Control and Prevention (CDC) staff. Venous blood in the amount of 6 mL was drawn from each participant in the morning and used for testing biochemical and nutritional indicators. Multivariate logistic regression analysis and Poisson regression analysis were used for overnutrition- and undernutrition-related disorders to test relevant personal, parental, and household factors. The prevalence of wasting, overweight, and obesity was 5.5%, 14.8%, and 12.7%, respectively. Metabolic syndrome (MetS) was prevalent among 5.1% of participants. Among the study participants, 29.5% had hyperuricemia. The overall prevalence of high low-density lipoprotein (LDL) and high total cholesterol (TC) of all participants was 4.8% and 7.4%, respectively. 0.9% of the participants had vitamin A deficiency (VAD) and 14.6% had marginal vitamin A deficiency; 25.1% had vitamin D deficiency (VDD) and 54.5% had inadequate vitamin D levels. Anemia was present in 4.0% of all participants. The prevalence of zinc deficiency was 4.8%. Demographic characteristics, behavioral characteristics, parents’ characteristics, and family characteristics were associated with these multiple malnutrition disorders. The double burdens of malnutrition, which includes overnutrition- and undernutrition-related diseases, were prevalent among the school-age children and adolescents in Jiangsu Province in eastern China. There were various factors related to different nutritional problems. Thus, health education focusing on behavior intervention and nutrition education are necessary in containing nutritional problems among children.

Relationship between Serum 25OH-Vitamin D2 Level and Vitamin D Status of Children Aged 3-5 Years in China

Background: Vitamin D deficiency is prevalent globally and there is lack of evidence as to how 25(OH)D2 contributes to vitamin D status. The aim of this study was to describe vitamin D status and to assess the role of vitamin D2, a dietary vitamin D source, against the vitamin D status of children aged 3–5 years in China. Methods: Data were extracted from the Chinese National Nutrition and Health Surveillance (CNNHS) in 2013. The concentration of serum 25(OH)D2 and 25(OH)D3 was measured by using LC-MS/MS. Results: A total of 1435 subjects were enrolled and serum 25(OH)D were analyzed. The prevalence of total serum 25(OH)D < 30 nmol/L was 8.9%. Serum 25(OH)D2 was detected in 10.9% of the studied children. After adjusting for confounding factors, total 25(OH)D concentration was 8.48 nmol/L lower and odds ratio of vitamin D deficiency was 4.20 times (OR (95%CI): 4.20 (1.64, 10.77)) in children without 25(OH)D2 than those with 25(OH)D2 detected. Conclusions: Vitamin D deficiency was common among children aged 3–5 years in China. Vitamin D2 may play a role in preventing vitamin D deficiency in Chinese children aged 3–5 years.

Vitamin D Status of Breastfed Filipino Infants Aged Less Than 6 Months in an Urban Community

PURPOSE

This study aimed to determine the serum 25-hydroxy-vitamin D (25(OH)D) status of breastfed infants less than six months old and their mothers, and factors affecting the status.

METHODS

This cross-sectional study was done on breastfed, term, Filipino infants less than six months old who were seen at local health centers and clinics in an urban area. The serum 25(OH)D levels of these infants and their mothers were determined, and their demographic data, nutritional status, sun exposure behavior, and maternal vitamin D intake were analyzed for correlation using regression models.

RESULTS

Among the 131 infants, 101 (77%) had vitamin D deficiency (VDD), which was defined as having 25(OH)D levels <37.5 nmol/L, and 13 (10%) had vitamin D insufficiency (VDI), with levels >37.5-50 nmol/L. Conversely, maternal VDD with levels <50 nmol/L was seen in 31 (24%) mothers and maternal VDI with levels 50-75 nmol/L, in 63 (48%) mothers. Infant age and maternal 25(OH)D status were independent predictors of infant VDD. Infants less than three months old were found to have a six-time increased risk of infant VDD (p=0.004). Infants who had mothers with VDD had a six-time increased risk, whereas those with maternal VDI had a four-time increased risk of infant VDD (p=0.049 and p=0.020, respectively).

CONCLUSION

Both infant and maternal VDD and VDI were seen to be highly prevalent in this tropical, urban community. Young infants and maternal VDD/VDI independently increased the risk of infant VDD, whereas lack of sun exposure of the mothers increased the risk for maternal VDI.

Vitamin D Status and Its Influence on the Health of Preschool Children in Hangzhou

Objective: Vitamin D deficiency and insufficiency in children are global public health problems. However, few studies have focused on vitamin D status in healthy preschool children, especially in Asia. This study aimed to investigate vitamin D status and host-related factors in healthy preschool children in Hangzhou to analyze the impact of low vitamin D levels (<30 ng/mL) on health outcomes (obesity, early childhood caries, and respiratory tract infections).

Methods: A total of 1,510 healthy children aged 24–72 months from 15 kindergartens in Hangzhou were included. Data on the children's gender, age, body mass index (BMI), caries, and blood samples available for vitamin D analysis were collected from June to August 2018. A total of 325 children aged 36–48 months took part in a survey on the frequency of respiratory tract infections in the last year.

Results: The children's mean 25(OH)D level was 28.01 ± 7.29 ng/mL. A total of 11.4% of the children had vitamin D deficiency, and 52.6% had vitamin D insufficiency. Only 36.0% had vitamin D sufficiency. No significant difference was found by gender or BMI group. However, children in the obesity group had the highest prevalence of vitamin D deficiency and the lowest 25(OH)D levels. A significant negative correlation was found between the 25(OH)D level and child age (r = −0.144, p < 0.001). Regression analysis showed that the children’s 25(OH)D levels decreased by 0.17 ng/mL per month with age. In addition, children with low vitamin D levels might increase the risk of obesity and early childhood caries. Multiple linear regression indicated that the number of caries in children increased by 0.08 per 1-ng/mL decrease in the 25(OH)D level (β = −0.08, p < 0.001).

Conclusion: Vitamin D deficiency/insufficiency is a serious problem among healthy preschool children in Hangzhou. Public health policies or interventions should be implemented to ensure that preschool children have adequate vitamin D to reduce the risk of related diseases.

Seasonal Changes in Vitamin D Levels of Healthy Children in Mid-Latitude, Asian Urban Area

PURPOSE

This study aimed to investigate the seasonal changes in vitamin D levels in a healthy pediatric population living in mid-latitude East Asian urban areas.

METHODS

A pediatric population was selected from single secondary hospital visitors. Clinical data and serum vitamin D levels were collected retrospectively. Statistical analyses were performed based on the month of the blood sampling date, subject age, and vitamin D supplementation history. The data were categorized into three subgroups based on serum vitamin D levels-adequate (≥30 ng/mL), insufficient (20-29 ng/mL), and deficient (<20 ng/mL).

RESULTS

Of the 481 patients, 172 had vitamin D supplementation history. More than 70% of the total study population had inadequate vitamin D levels (<30 ng/mL). The non-supplemented group and the supplemented group showed significantly uneven monthly distribution of the adequate, insufficient, and deficient subgroups. Only the non-supplemented group showed significantly different average vitamin D levels in the summer months compared to the winter months. In the non-supplemented group, vitamin D levels were the lowest in March, the highest in August and September. Significant relevance was noted between vitamin D supplementation status and vitamin D serum level in February and March. There was no significant difference between different age groups in terms of the distribution of vitamin D levels.

CONCLUSION

Currently-widespread vitamin D replacement methods seem to have some effect on increasing the overall serum vitamin D levels, specifically during late winter when natural serum vitamin D levels plunge. However, they are unable to fully compensate the seasonal fluctuation.

Association of serum 25-Hydroxyvitamin D with Vitamin D intervention and outdoor activity among children in North China: an observational study

Background

Living at high latitudes is one of the risk factors for vitamin D deficiency in children. However, evidence on vitamin D improvement for this pediatric population to date is limited. This study aims at evaluating the association of different vitamin D intervention methods and outdoor activity on the vitamin D status of children in North China.

Methods

In this observational study, a total of 55,925 children aged 1 month to 18 years old were recruited from pediatric outpatient departments from July 2016 to June 2017. Data on demographics, anthropometric measurements, vitamin D intervention (either prescribed by physicians or given by parents) and outdoor activity were recorded. The serum levels of 25-hydroxycholecalciferol (25(OH)D) were determined by high performance liquid chromatography tandem–mass spectrometry. Logistic regression analysis was performed to assess the association of vitamin D intervention or outdoor activity with blood vitamin D status, adjusted for age, gender, BMI for age, and seasons.

Results

The overall rate of hypovitaminosis D was 65.60%. Of the children’s outdoor activity, 35.63, 31.95, and 32.42% were below 30 min/d, 30–60 min/d and over 60 min/d, respectively. Furthermore, the proportion of therapeutic intervention, supplementation intervention and no vitamin D intervention among the children was 16.48, 32.87, and 50.65%, respectively. After adjusted for confounding factors, vitamin D intervention was associated with a lower risk of hypovitaminosis D, with OR (95% CI) of 0.191 (0.180, 0.202) in children with therapeutic doses and 0.423 (0.404, 0.443) in those with supplementation doses, compared with children without vitamin D intervention. In addition, longer outdoor time was associated with a lower risk of hypovitaminosis D [0.479 (0.456, 0.504) for 60 min/d, 0.737 (0.701, 0.776) for 30–60 min/d], independent of vitamin D intervention.

Conclusions

High prevalence of vitamin D deficiency was found in children living at high latitudes. Vitamin D intervention and outdoor activity are all negatively associated with children’s vitamin D deficiency. Routine vitamin D intervention combined with increased outdoor time might be an effective approach to prevent hypovitaminosis D among children, especially those at school, living at high latitudes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12887-020-02435-9.

Sociodemographic disparity in the nutritional status among children and adolescents in Zhejiang Province

OBJECTIVE

To explore the sociodemographic disparity in the nutritional status including BMI, vitamin D and vitamin A status among children and adolescents in Zhejiang Province.

METHODS

Weight, height serum 25-hydroxyvitamin D, and serum retinol were assessed in 2818 children and adolescents (6-17 years of age), using ten investigation sites in Zhejiang Province including urban and rural areas data from the China National Nutritional Study 2016-2017, which is a nationally representative cross-sectional study, to form provincial representative sample of Zhejiang Province. Sociodemographic disparity was explored.

RESULTS

The prevalence of low weight, eutrophic, overweight and obese were 6.7%, 70.4%, 11.6%, and 11.2%, respectively. Significant difference was observed on BMI between males and females (P < 0.05), and between urban and rural areas (P < 0.05). The prevalence of vitamin D deficiency, inadequacy, normal and appropriate were 1.8%, 34.9%, 46.4% and 16.9%, respectively. Significant difference was observed on the concentration of 25-hydroxyvitamin D (25(OH)D) both between genders and between living areas (P < 0.05). The prevalence of vitamin A deficiency, marginal deficiency and appropriate were 4.5%, 24.7%, and 70.9%, respectively. Significant difference was observed on the concentration of retinol between living area (P < 0.05).

CONCLUSIONS

Overweight and obesity, deficiency and inadequacy of vitamin D, deficiency and marginal deficiency of vitamin A were prevalent among children and adolescents. There were disparities between genders and between living areas on the nutritional status. Regional and sex-specific guidelines and public health policies for children and adolescent nutrition are needed.

An Investigation of Vitamin Levels Status in the Serum of Children in China

This study was to investigate the vitamin levels in the serum of children in the Northeast of China and some factors associated with the vitamin levels. The sera were obtained from 2096 normal children aged 1 month to 12 years in the Northeast of China. Vitamins A and E were detected using their sera by HPLC, and the level of vitamin D was detected by LC-MS. The 20 overweight children were chosen from the 7-8 age range and took additional vitamins studies for extra 3 months. The data were analyzed by IBM SPSS Statistics 21. The average levels of vitamins A, D, and E in sera samples from the 2096 children were 0.2715mg/L (95%CI, 0.2715-0.2791mg/L), 26.2848μg/L (95%CI, 25.7900-26.7786μg/L), and 8.6137mg/L (95% CI, 8.5077-8.7198mg/L), respectively. The percentages of vitamins A, D, and E deficiency were 19.61%, 47.47%, and 0.62%, respectively. For 20 children from the VDD or VAD groups, after giving them more VA and VD for 3 months, the levels of VA and VD in the sera were increased significantly; however, the average BMI has barely changed. According to our finding, vitamin D deficiency was severe, vitamin A deficiency was common, and vitamin E was insufficient in the sera of children in the Northeast of China. The levels of vitamins A, D, and E were correlated with age and overweight.

25-Hydroxyvitamin D Status and Its Association with Sleep Duration in Chinese Schoolchildren

OBJECTIVE

To examine the association between 25-Hydroxyvitamin D (25(OH)D) levels and sleep duration among Chinese adolescents.

SUBJECTS AND METHODS

A school-based cross-sectional study was conducted among Chinese adolescents in 2017. Data on a total of 800 adolescents aged 8⁻14 years was used for this study. Anthropometric measurements such as height and weight were measured by trained research staff. Serum 25(OH)D and lipids were measured in the laboratory. Sleep habits and other health-related behaviors were tested by questionnaire.

RESULTS

25(OH)D levels were significantly positively correlated with sleep duration (r = 0.11, p < 0.05). In multivariate logistic regression analyses, insufficiency/deficiency of vitamin D (25(OH)D ≤ 20 ng/mL) was significantly associated with increased probability of short sleep (AOR = 1.67, 95% CI = 1.14⁻2.43).

CONCLUSIONS

Low 25(OH)D levels were independently associated with the risk of insufficient sleep in Chinese adolescents.

Prevalence of vitamin D insufficiency among children in southern china: A cross-sectional survey

Vitamin D deficiency is associated with numerous public health issues. Limited data are available for children in southern China, a region that receives abundant sunlight. We aimed to estimate the 25-hydroxyvitamin D (25(OH)D) levels in children in that area, and to determine seasonal variations in serum 25(OH)D levels. A total of 16,755 children aged 0 to 6 years, who visited the Guangdong Women and Children's Hospital for health examination between January 2016 and May 2017, were included in the present study. The serum 25(OH)D levels ranged from 10.5 to 307.4 nmol/L (mean ± standard deviation: 78.5 ± 26.3 nmol/L). The prevalence of vitamin D deficiency and insufficiency were 10.8% and 39.0%, respectively. The mean serum 25(OH)D level in spring (71.8 ± 24.9 nmol/L) was lower than that in other seasons. From January to April, we found a relatively high prevalence of vitamin D deficiency or insufficiency, both of which were also found to increase with age. Logistic regression analysis revealed that vitamin D deficiency and insufficiency were significantly associated with age and season. Deficiency and insufficiency of vitamin D are common among children in southern China, despite the area receiving sufficient sunlight.

Association between Vitamin D deficiency and psoriasis: An exploratory study

INTRODUCTION

Deficiency of Vitamin D is a widespread problem. Vitamin D could have important immune modulatory effects in psoriasis.

OBJECTIVE

Aimed to review and endeavored to establish the relationship, if any, between deficiency of Vitamin D and psoriasis.

METHODS

Leading studies that examined the relationship between deficiency of Vitamin D and psoriasis were reviewed from July2016 to October 2016. An electronic published work search was performed using PubMed, Ovid MEDLINE, Google Scholar, and Saudi Digital Library.

RESULTS

A total of 2132 eligible articles were identified by the electronic search. The titles and abstracts of 954 articles fulfilled the criteria of midline search. 20 articles were included after application of inclusion standards and full-text review. These 20 studies included 2046 psoriatic patients with or without arthritis and 6508 healthy controls. 14 studies show a positive correlation between Vitamin D deficiency and psoriasis. These 14 studies included 1249 psoriatic patients with or without arthritis and 680 healthy controls. Remaining six studies, including 797 psoriatic patients with or without arthritis and 5828 healthy controls do not depict a positive correlation between the two variables under study.

CONCLUSION

There exists a correlation of psoriasis with deficiency of Vitamin D. However, there is a need for larger scale case-control studies to assess how far Vitamin D deficiency plays a role in psoriasis.

Vitamin D Nutritional Status and its Related Factors for Chinese Children and Adolescents in 2010-2012

Vitamin D plays a critical role in calcium and phosphate metabolism and helps maintain skeletal integrity in childhood, yet vitamin D status in Chinese children and adolescents is not well documented. The aim of this study was to assess the vitamin D status and analyze the risk factors for vitamin D deficiency in Chinese children and adolescents aged 6-17 years. Serum 25 hydroxyvitamin D (25(OH)D) was measured with a radioimmunoassay kit in 15,000 children and adolescent participants in the Chinese national nutrition and health survey (CNNHS) 2010-2012. Age, gender, region type, ethnicity, outdoor time, and vitamin D supplementation were recorded in unified design questionnaires. The season was recorded by the date of blood taken; location was divided into north and south by China's Qinling Mountains and Huaihe River; and ambient ultraviolet B (UVB) radiation level was classified according to the corresponding dose of each participant living area from National Aeronautics and Space Administration data. 14,473 participants from the cross-sectional study of CNNHS 2010-2012 were included in this study. The median serum 25(OH)D concentration was 48.2 (35.4-63.4) nmol/L, and the concentration for males was 50.0 (36.5-65.7) nmol/L, which was statistically higher than that of females (46.7 (34.4-60.9) nmol/L) (P < 0.001). The general prevalence of vitamin D deficiency was 53.2%; 50.0% for males and 56.5% for females at the cut-off 50 nmol/L. According to the results of the log-binomial regression analysis, vitamin D deficiency in Chinese children and adolescents was specifically related to female gender (P < 0.0001), to ages 12-14 years (P < 0.0001) and 15-17 years (P < 0.0001), living in large cities (P < 0.0001) or ordinary rural areas (P < 0.0001), low ambient UVB levels (P < 0.0001) and medium ambient UVB levels (P < 0.0001), spring (P < 0.0001), autumn (P < 0.0001) and winter seasons (P < 0.0001). The data showed that vitamin D deficiency was very common among children and adolescents aged 6-17 years in China. Effective sun exposure should be encouraged in both genders aged 6-17 years, dietary vitamin D and vitamin D supplements are also recommended, especially in the seasons of spring and winter.

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.

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.