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

Is vitamin D supplementation program in Iranian schools effective in reducing adolescent depressive symptoms? Cost effectiveness study

PURPOSE

We aimed to assess the cost-effectiveness of the vitamin D supplementation program in Iranian adolescents reducing adolescent depressive Symptoms.

METHODS

In the current cost-effectiveness analysis, the viewpoint of Iran's Ministry of Health was selected. The target population was 1,519,762 Iranian high school students (733,657 girls and 786,105 boys). The total costs of the vitamin D supplementations program were based on the reports of the Nutrition Improvement Office of Iran's Ministry of Health and were adjusted to 2018. The variable of Quality-Adjusted Life Years (QALYs) was considered a suitable variable for estimating the effectiveness of vitamin D supplementation. We chose one year as the time horizon. A decision tree model was constructed in TreeAge Pro. The results of the cost-effectiveness analysis were reported in term of the Incremental Cost-Effectiveness Ratio (ICER).

RESULTS

The results of our study showed that the estimated cost per QALY gained of the vitamin D supplementation program is equal to 1528.6676 $, which indicates that vitamin D supplementation in adolescents(11-18Y) is a cost-effective and a dominant strategy in preventing depression through the cost-saving and QALYs increment compared to the no intervention. Sensitivity analysis showed that the possible variations in vitamin D supplement costs could not alter the results, and vitamin D supplementation may be a predominant and cost-effective strategy to prevent adulthood depression with a 100% probability.

CONCLUSION

The national program of vitamin D supplementation among Iranian adolescents was a cost-efficient strategy reducing adolescent depressive Symptoms through the cost-saving and QALYs increment compared to the no intervention.

The association between vitamin D deficiency and metabolic syndrome in Ukrainian adolescents with overweight and obesity

PURPOSE

This work aims to determine the association between vitamin D deficiency and metabolic syndrome in overweight and obese adolescents from Ukraine.

METHODS

Anthropometric measurements were taken and general and biochemical examinations were performed on 136 obese and overweight adolescents and 60 adolescents with normal body weight. The vitamin D status was determined using 25-hydroxyvitamin D (25(OH)D) (calcidiol) levels in blood serum. To establish the factors influencing vitamin D status, the subjects were asked to answer a questionnaire and 2007 International Diabetes Federation diagnostic criteria were used to determine the incidence of metabolic syndrome. All research results were processed statistically.

RESULTS

A calcidiol sufficiency level was found in 3.9% of obese adolescents and 6.7% of overweight adolescents. Metabolic syndrome was found in 64.4% of obese adolescents with vitamin D deficiency, and in 26.2% of overweight adolescents. Factors associated with an increased risk of developing vitamin D deficiency in adolescents with metabolic syndrome included male sex (p=0.042), low income per family member (p=0.040), daily milk consumption of up to 1 cup per day (p=0.001), physical activity (p=0.001), duration of outdoor stays (p=0.001), and passive rest in front of a computer or television (p=0.001). Adolescents with metabolic syndrome were found predominance of body mass index (p<0.001), waist circumference (p<0.001), fasting blood glucose level (Р<0.001), and decreased calcidiol level (p=0.022). Among metabolic syndrome components, vitamin D deficiency was strongly associated with waist circumference and increased fasting blood glucose (p<0.05).

CONCLUSION

Vitamin D deficiency is prevalent in overweight and obese adolescents from Ukraine. Vitamin D deficiency is associated with metabolic syndrome criteria in overweight and obese adolescents.

The Effect of Vitamin D Deficiency with Stunting and Overweight: A Meta-analysis Study

Background: Childhood malnutrition such as stunting and obesity is an international public health problem leading to an increased risk of mortality and morbidity. Vitamin D deficiency has also been identified as a worldwide public health issue that is associated with an increase in the prevalence of related-chronic diseases. Aim: The purpose of this study was to investigating the relation between vitamin D deficiency with stunting and  overweight  among children. Methods: This was a systematic review and meta analysis study used articles from online database of PubMed, which published in 2011 to 2021. The dependent variables was stunting and overweight. The independent variable was vitamin D deficiency. The data was analyzed by RevMan. Results: Subjects with below-standard vitamin D levels in the body had 1.86 higher risk of experiencing stunting (OR = 1.86; 95% CI 0.90-3.84; p = 0.09) and 2.76 higher being overweight (OR = 2.76; 95% CI 0.96-7.99 ; p = 0.09) compared with those with normal vitamin D levels, this result was not statistically significant. Conclusion: There is a relation between vitamin D deficiency with stunting and overweight among children under 18 years

The association between vitamin D levels and metabolic syndrome components among metropolitan adolescent population

OBJECTIVES

Vitamin D promotes both lipolysis and lipogenesis, and some pediatric studies showed inconsistent associations between vitamin D and metabolic syndrome (MetS). This cross-sectional study aimed to examine the association between vitamin D levels and MetS components among metropolitan adolescents.

METHODS

A total of 4,149 adolescents aged 10-18 years were recruited from 23 metropolises in China. The MetS conditions were assessed according to the International Diabetes Federation consensus definition, and the serum 25-hydroxy vitamin D (25(OH)D) concentrations were analyzed. The association between MetS components and serum 25(OH)D levels was analyzed by the logistic regression model. Restricted cubic spline was applied to the model nonlinear association.

RESULTS

Prevalence of vitamin D deficiency was 74.9%, and 41.2% of study participants had at least one MetS component. After adjustment, the significant trend for a lower waist-to-height ratio was not observed in study participants with higher serum 25(OH)D quartile (p=0.57), but a significant nonlinear association between abdominal obesity and serum 25(OH)D levels was found (p=0.04): the highest risk of abdominal obesity occurred at 14.1 ng/mL of serum 25(OH)D. The association of serum 25(OH)D was significantly inverse with MetS (OR: 0.95; 95% CI: 0.92-0.98), but not with raised triglycerides (OR: 0.99; 95% CI: 0.96-1.01), raised blood pressure (OR: 0.99; 95% CI: 0.97-1.01) and impaired fasting glycemia (OR: 1.03; 95% CI: 1.01-1.04).

CONCLUSIONS

The net effect of vitamin D on lipid metabolism may be concentration-dependent, and the actual effect of vitamin D on MetS process may be complex among metropolitan adolescents, though serum 25(OH)D is inversely associated with MetS.

Vitamin D and Calcium Status Among Adolescents with Morbid Obesity Undergoing Bariatric Surgery

PURPOSE

Obesity is very prevalent among children and adolescents these days. Obese children are at increased risk of vitamin D and other micronutrient deficiencies. This risk is even higher in children and adolescents with morbid obesity who are candidates for bariatric surgery. Although multiple studies have studied the prevalence of vitamin D deficiency in adults undergoing bariatric surgery, studies are limited concerning adolescents in this regard. We aimed to study the prevalence of vitamin D deficiency and insufficiency and calcium status among morbidly obese children and adolescents.

MATERIALS AND METHODS

A number of 96 adolescents (20 years old and younger) with morbid obesity (BMI ≥ 99% percentile), who were candidates for bariatric surgery, were enrolled in this study (from 2016 to 2018), and their serum vitamin D and calcium levels were measured.

RESULTS

Sixty-four percent of the patients were vitamin D-deficient and 15.7% of them had insufficient levels of serum vitamin D. Only 20.2% of the children had sufficient serum vitamin D levels. Serum calcium levels were within the normal range among all of the patients. There was no significant relationship between age and sex with vitamin D levels.

CONCLUSION

Vitamin D deficiency is of very high prevalence among adolescents with morbid obesity.

Association of vitamin D status and cardio-metabolic risk factors in children and adolescents: the CASPIAN-V study

BACKGROUND

Metabolic syndrome (MetS) starts from early life and is one of the important underlying factors for non-communicable diseases (NCDs) in adulthood. Controversial evidence exists on the role of vitamin D deficiency in increasing the risk of pediatric MetS.

OBJECTIVE

This study aimed to assess the relationship between vitamin D level with MetS and its components in children and adolescents.

METHODS

This nationwide cross-sectional study was performed as part of a surveillance program in Iran. Participants were 2596 students, aged 7 to 18 years, living in 30 provinces. In addition to filling questionnaires, a physical examination was conducted, and blood samples were collected. The serum concentration of 25-hydroxy vitamin D (25(OH)D) was measured using the direct competitive immunoassay chemiluminescence method.

RESULTS

2596 students with a mean age of 12.2 y (55.1% boys) were recruited. Prevalence of vitamin D deficiency and insufficiency in participants was 10.6% (n = 276), and 60.5% (n = 1570), respectively. The prevalence of MetS was higher in the vitamin D deficient group. Students with deficient vitamin D levels had higher odds of MetS (OR: 4.25, 95%CI: 2.26-7.98), abdominal obesity (OR: 2.24, 95%CI: 1.61-3.12), low HDL-C (OR: 1.65, 95%CI: 1.18-2.30) and high fasting blood sugar (OR: 2.56, 95%CI: 1.43-4.57) in comparison to those with sufficient level of vitamin D.

CONCLUSION

Vitamin D deficiency was associated with increased odds of MetS and its components in the Iranian pediatric population. These findings underscore the importance of prevention and control of vitamin D deficiency in preventative programs against NCDs.

Circulating serum vitamin D levels in relation to metabolic syndrome in children: A systematic review and dose-response meta-analysis of epidemiologic studies

Findings from epidemiologic studies that evaluated the relationship between serum vitamin D levels and metabolic syndrome (MetS) in children were contradictory. We conducted a systematic review and meta-analysis on the relation of serum 25(OH)D levels and MetS in children. A comprehensive search was conducted in electronic databases, up to November 2020. Eleven cross-sectional studies that reported the link between circulating vitamin D levels and MetS in children were included in the analysis. Combining 11 effect sizes from 11 cross-sectional studies with 22,196 participants revealed that highest versus lowest serum vitamin D concentration was significantly associated with a 50% reduced odds of MetS in children (OR: 0.50; 95%CI: 0.39, 0.64). Subgroup analysis by study location revealed decreased odds of MetS in both non-Asian (OR: 0.45; 95%CI: 0.33, 0.63) and Asian countries (OR: 0.54; 95%CI: 0.39, 0.76) with no heterogeneity in these subgroups. When we confined the studies to those with representative populations (n = 21,611), a significant inverse association was found between highest versus lowest circulating vitamin D level and MetS (OR: 0.55; 95%CI: 0.42, 0.71). Dose-response analysis showed that each 10 ng/ml (or 25 nmol/L) in serum vitamin D was linearly related to a 12% reduced odds of MetS (OR: 0.88; 95%CI: 0.78, 0.99) in children. A nonlinear association was also detected between serum 25(OH)D and MetS. This meta-analysis revealed that circulating vitamin D concentration was inversely associated with odds of MetS in children, in a dose-response fashion. The same finding was found in the studies with representative populations.

The cost-effectiveness analysis of a nationwide vitamin D supplementation program among Iranian adolescents for adulthood cardiovascular diseases prevention

OBJECTIVE

This study aimed to evaluate a national vitamin D supplementation program's cost-effectiveness among Iranian adolescents to prevent cardiovascular diseases (CVDs) in adulthood.

STUDY DESIGN

A cost-effectiveness analytical study.

METHODS

A decision tree model was adopted to evaluate the cost per quality-adjusted life-year (QALY) of monthly intake of nine pearls of 50,000 IU vitamin D for nine months to prevent CVD a one-year horizon compared to no intervention. The analysis was conducted in Iranian adolescents in first or second high school grades of 47 climatically different Iran regions.

RESULTS

Our analytical analysis estimated the 1090$ cost per QALY gained of the monthly intake of 50,000 IU vitamin D for nine months among adolescents over a one-year horizon. Based on the incremental cost-effectiveness ratio (ICER) threshold of 1032-2666, vitamin D supplementation was cost-effective for adolescents to prevent adulthood CVD. It means that vitamin D supplementation costs were substantially less than the costs of CVD treatments compared to the no intervention.

CONCLUSIONS

Based on these findings, the national program of vitamin D supplementation in adolescents would be cost effective to prevent CVD development in adulthood. From an economic perspective, vitamin D supplementation, especially in adolescents with vitamin D deficiency, would be administrated.

The study of Iranian children and adolescents' physical activity: a systematic review and meta-analysis

OBJECTIVES

This systematic and meta-analysis review was conducted to determine the status of Iranian children and adolescents' physical activity.

CONTENT

All the related articles which were published in the major databases, including Pubmed, Scopus, Web of Science, Embase, Magiran, SID from the beginning of 2010 to the end of 2019, were reviewed by researchers. The Newcastle-Ottawa scale was also used to evaluate the quality of articles. Moreover, I ² index and chi-square were used to assess the heterogeneity between the results.

SUMMARY

490 articles were found as a result of the search in the selected international and local databases, where finally, 10 articles were included into the meta-analysis after the elimination of the duplicated articles and applying inclusion and exclusion criteria. The results indicated that 29.5% of the girls were considered active according to WHO criteria (16.1-42.8: 95% CI) and also 20.5% of the boys (7.3-33.7: 95% CI).

OUTLOOK

Overall, this study's findings showed that a large percentage of Iranian children and adolescents do not achieve the level of physical activity recommended by the World Health Organization. This can lead to undesirable consequences for this group of population that is considered as the human capital of any country; consequently, it seems necessary to take basic measures at the micro and macro levels in order to reduce such problems in the society.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Prevalence and Incidence of Metabolic Syndrome in Iran: A Systematic Review and Meta-Analysis

Metabolic syndrome (MetS) is a predictor of several diseases such as cardiovascular diseases, diabetes, dyslipidemia, stroke, osteoarthritis, certain cancers, and death leading to public health concern in most societies. We aimed to estimate the pooled prevalence and incidence of MetS in Iranian population through a meta-analysis study. We included cross-sectional and cohort studies to estimate the overall prevalence and incidence rates of MetS in Iran National databases including MagIran, Science Information Database, IranMedex, and international databases including Medline, Web of Sciences, and Scopus were searched up to October 2017. Finally, 125 studies were included. The total sample size was 472,401 with a mean age of 38 ± 7.8 years. The overall pooled prevalence and incidence rate among the general population of Iran was 0.26 (95% CI: 0.26, 0.29) and 97.96 (95% CI: 75.98, 131.48), respectively. The pooled prevalence of MetS was higher in females and in urban areas. The highest and lowest prevalence of MetS was obtained by the Iranian definition criteria (0.43) and the NHANES III (0.12). The highest and lowest incidence rates of MetS were obtained by IDF (144.07 per 1000) and the JIS (89.73 per 1000). The prevalence of MetS was higher in women and those living in urban areas. Furthermore, the prevalence of MetS increased with increasing age in both genders.

Association of Vitamin D Status and Metabolic Syndrome Components in Iranian Children

Background:

Recently, it has been found that Vitamin D can affect cardiometabolic risk factors. However, these findings have not been confirmed in younger population. We aimed to assess the associations of serum 25-hydroxyvitamin D (25(OH)D) and metabolic syndrome (MetS) components in Iranian children.

Methods:

This cross-sectional study was conducted on 240 children aged 6–9 years old. Anthropometric indices (weight, height, waist circumference, and body fat), biochemical parameters (low-density lipoprotein, high-density lipoprotein, triglyceride [TG], fasting blood sugar, and serum 25(OH)D), systolic blood pressure (SBP) and diastolic blood pressure (DBP) blood pressure, and dietary intake and physical activity were measured. Multivariate linear regression analysis was used to assess the association of MetS components and serum 25(OH)D.

Results:

Mean age of children was 7.8 ± 1.06 year. Mean serum 25(OH)D concentration was 14.6 ± 10.64 ng/ml, and the prevalence of Vitamin D deficiency (serum 25(OH)D lower than 10 ng/ml) was 41.66%. Dietary intake of Vitamin D was 1.91 ± 1.8 mcg/day. Serum 25(OH)D was inversely associated with TG (β = −0.16; CI: −0.27, −0.04) after adjusting by age, gender, body mass index, physical activity, and some dietary components. Serum 25(OH)D was negatively associated with SBP (β = −0.02; CI: (−0.05, −0.004), and DBP (β = −0.02; CI: −0.05, −0.003); however, it was not significant anymore after adjustment for sodium, potassium, and fiber.

Conclusions:

Vitamin D deficiency is alarming among Iranian children. Among the components of MetS, lower serum Vitamin D concentration was only associated with TG that could contribute in onset and progression of cardiometabolic disorders later in life.

Prevalence of vitamin D deficiency in Iran: A systematic review and meta-analysis

BACKGROUND

The prevalence of vitamin D deficiency in the Iranian community is very high. Women and older people are at the higher risk of vitamin D deficiency.

AIM

This study aimed to estimate the prevalence of vitamin D deficiency in Iran by combining the results of various studies.

METHODS

This was a systematic review and meta-analysis. Separate strategies were developed for search in national databases (Irandoc, Magiran, SID) and international databases (Web of Science, PubMed, and Scopus) using the keywords of "vitamin D deficiency," "Iran," and "prevalence." The titles and abstracts of the articles were screened and related full texts were appraised. Those articles that met inclusion criteria were selected for meta-analysis. The heterogeneity of the articles was assessed via the Chi-square test. They were combined using the random-effect approach. In addition, the groups were categorized and analyzed in terms of age and gender.

RESULTS

Of 639 articles, 30 articles with a sample size of 26,042 people were included for data analysis. The overall prevalence of vitamin D deficiency was reported as 0.56. Subgroup analysis showed that 0.64 of women and 0.44 of men were suffering from vitamin D deficiency. The prevalence of vitamin D deficiency in the age groups under 20, 20-50, and over 50 years was 0.56.4, 0.72.4, and 0.59.8, respectively.

CONCLUSIONS

The Iranian Ministry of Health is expected to design strategies to improve the status of vitamin D at the national level.

Vitamin D levels are associated with metabolic syndrome in adolescents and young adults: The BCAMS study

BACKGROUND AND AIMS

The relationship between vitamin D deficiency and metabolic syndrome (MS) remains controversial with relatively sparse data among youth. Therefore, we attempted to explicate the association of 25-hydroxyvitamin D [25(OH)D] levels with MS in Chinese adolescents and young adults.

METHODS

A cohort of 559 subjects at elevated risk of MS were recruited at 14-28 years of age as a follow-up to the Beijing Child and Adolescent Metabolic Syndrome Study. Subjects underwent clinical assessment including a 2h-oral glucose tolerance test. The concentrations of 25(OH)D, glucose, insulin and lipids were determined. MS was defined using the 2009 harmonized definition.

RESULTS

The prevalence of vitamin D deficiency (< 20 ng/ml) was 78.3%. After adjusting for age, gender and season, 25(OH)D concentrations were negatively correlated with neck circumference, percent body fat, LDL cholesterol, fasting and 2h-glucose levels (all P < 0.05). 25(OH)D levels were significantly lower in participants with obesity, high triglycerides, type 2 diabetes, or MS, compared to their respective counterparts (all P < 0.05). After adjusting for potential confounders (e.g., body mass index), participants in the lowest 25(OH)D tertile were 2.5 times more likely to exhibit MS than were those in the highest tertile (Odds Ratio: 2.48; 95% CI: 1.13-5.45, P < 0.05).

CONCLUSIONS

Vitamin D deficiency was very common in this young Chinese population at risk for MS. Given this association between low vitamin D levels and MS, the role of vitamin D supplementation in Chinese youths needs further examination, particular in those at risk for MS.

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.

Vitamin D deficiency causes inward hypertrophic remodeling and alters vascular reactivity of rat cerebral arterioles

Background and purpose

Vitamin D deficiency (VDD) is a global health problem, which can lead to several pathophysiological consequences including cardiovascular diseases. Its impact on the cerebrovascular system is not well understood. The goal of the present work was to examine the effects of VDD on the morphological, biomechanical and functional properties of cerebral arterioles.

Methods

Four-week-old male Wistar rats (n = 11 per group) were either fed with vitamin D deficient diet or received conventional rat chow with per os vitamin D supplementation. Cardiovascular parameters and hormone levels (testosterone, androstenedione, progesterone and 25-hydroxyvitamin D) were measured during the study. After 8 weeks of treatment anterior cerebral artery segments were prepared and their morphological, biomechanical and functional properties were examined using pressure microangiometry. Resorcin-fuchsin and smooth muscle actin staining were used to detect elastic fiber density and smooth muscle cell counts in the vessel wall, respectively. Sections were immunostained for eNOS and COX-2 as well.

Results

VDD markedly increased the wall thickness, the wall-to-lumen ratio and the wall cross-sectional area of arterioles as well as the number of smooth muscle cells in the tunica media. As a consequence, tangential wall stress was significantly lower in the VDD group. In addition, VDD increased the myogenic as well as the uridine 5’-triphosphate-induced tone and impaired bradykinin-induced relaxation. Decreased eNOS and increased COX-2 expression were also observed in the endothelium of VDD animals.

Conclusions

VDD causes inward hypertrophic remodeling due to vascular smooth muscle cell proliferation and enhances the vessel tone probably because of increased vasoconstrictor prostanoid levels in young adult rats. In addition, the decreased eNOS expression results in endothelial dysfunction. These morphological and functional alterations can potentially compromise the cerebral circulation and lead to cerebrovascular disorders in VDD.

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

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

The Association Between Vitamin D Deficiency and Metabolic Syndrome in Korean Adolescents

PURPOSE

This study aimed to analyze the demographic characteristics associated with vitamin D deficiency, as well as the association between vitamin D deficiency and metabolic syndrome, among Korean adolescents.

DESIGN AND METHODS

This cross-sectional descriptive study involved 2314 adolescents aged 12-18years. Participant data were extracted from the Korean National Health and Nutrition Examination Survey conducted between January 2010 and December 2014. A logistic regression analysis was performed to analyze the association between vitamin D and metabolic syndrome. All analyses were performed using IBM SPSS Statistics 24.

RESULTS

Among the participants, 78% exhibited vitamin D deficiency and 7.8% had metabolic syndrome. The vitamin D deficient and sufficient groups differed significantly in terms of age, sex, household income, and self-perceived health status. Among the subcomponents of metabolic syndrome, vitamin D deficiency was associated with a 2.07-fold higher risk of elevated fasting blood glucose (≥100mg/dL).

CONCLUSIONS

The association of vitamin D deficiency with an increased risk of elevated fasting blood glucose levels suggests that adolescents in this population should receive interventions to prevent and manage diabetes. In the future, the effects of vitamin D deficiency on chronic health problems, including diabetes, should be investigated in adolescents.

PRACTICE IMPLICATIONS

Adolescents with vitamin D deficiency should be screened for prediabetes, and clinicians should be concerned about both the diagnosis and prevention of diabetes in this population.

Physical Activity, Sedentary Behavior, Cardiorespiratory Fitness and Metabolic Syndrome in Adolescents: Systematic Review and Meta-Analysis of Observational Evidence

Background

Metabolic syndrome (MetS) has been diagnosed in adolescents and among the associated factors are low levels of physical activity, sedentary behavior over long periods and low cardiorespiratory fitness. However, specifically in adolescents, studies present conflicting results. The aim of the present study was to conduct a systematic review and meta-analysis of observational studies, in order to map the association between physical activity, sedentary behavior, cardiorespiratory fitness and MetS in adolescents.

Methods

A search was performed in the databases PubMed, SPORTDiscus, LILACS and the Cochrane Library. For the meta-analysis, the odds ratio (OR) was calculated together with the respective confidence intervals (95% CI), in which the measures of effect were analyzed by dichotomous data (exposure variables) with MetS used as events.

Results

Eighteen studies were included in the meta-analysis. Primary analysis demonstrated that low levels of physical activity (OR = 1.35 [1.03 to 1.79]; p = 0.03) and low cardiorespiratory fitness (OR = 4.05 [2.09 to 7.87]; p < 0.01) were significantly associated with the development of MetS, while for sedentary behavior, represented by screen time > 2 hours/day, a significant association was not identified (OR = 1.20 [0.91 to 1.59]; p = 0.20). Subgroup analyses demonstrated that the association between low physical activity and MetS was dependent on the use of the accelerometry technique (OR = 2.93 [1.56 to 5.47]; p < 0.01). Screen time > 2 hours/day was significantly associated with MetS only on weekends (OR = 2.05 [1.13 to 3.73]; p = 0.02). With respect to cardiorespiratory fitness, a significant association with MetS was found independent of the maximal oxygen uptake (VO₂max) measurement method.

Conclusions

Low levels of physical activity, low indices of cardiorespiratory fitness and sedentary behavior, represented by screen time > 2 hours/day on weekends, were significantly associated with the development of MetS in adolescence.

Vitamin D Deficiency is Associated with Overweight and/or Obesity among Schoolchildren in Central Ethiopia: A Cross-Sectional Study

Childhood and adolescent obesity is an international public health problem leading to an increased risk of adulthood obesity, mortality and morbidity. Its prevalence is increasing in low-income populations, and we hypothesized it may be associated with vitamin D deficiency. Low vitamin D status is a worldwide public health issue including in Ethiopia; however, no one has examined overweight/obesity in Ethiopian schoolchildren with regard to vitamin D status. The Analyses of a data set from a school-based cross-sectional study conducted in Adama Town (n = 89) and in rural Adama Woreda (n = 85) was carried out to determine vitamin D deficiency and its association with overweight and/or obesity. Data on a total of 174 schoolchildren aged 11-18 years was used for these analyses. The overall prevalence of overweight and/or obesity was 10.3%, with 8.5% overweight and 2.3% obese; the prevalence of underweight was 19%. In the multivariable logistic regression model, vitamin D deficiency, being in the higher age group, female sex and urban residence of students, their mothers' occupation of being employed and their households' high and middle socioeconomic status were significantly associated with overweight and/or obesity. We concluded that vitamin D deficiency is an independent predictor significantly associated with overweight and/or obesity among schoolchildren from rural and urban settings in Ethiopia. The results imply the need for behavior change communications on the importance of exposure to sunlight to produce adequate vitamin D to curb this emerging health problem of overweight/obesity following economic growth and globalization in Ethiopia. As this study only highlighted the association, prospective studies and randomized controlled trials are required to establish causality.

Determinants of vitamin D deficiency among undergraduate medical students in Saudi Arabia

BACKGROUND/OBJECTIVES

The objectives of our study were to determine possible factors associated with low vitamin D levels in medical students.

SUBJECTS/METHODS

A cross-sectional study was performed among 255 first- to fifth-year male undergraduate medical students of one of the major universities in Saudi Arabia. Serum 25-hydroxyvitamin D (25(OH)D) levels were measured using electrochemiluminiscence. Multiple logistic regression analysis was performed.

RESULTS

Majority of Saudi medical students (75.2%) had 25(OH)D levels <30 nmol/l, defined as risk for deficiency by the Institute of Medicine. Multivariate analysis showed that the odds of having 25(OH)D serum levels of ⩾ 30 nmol/l were seven times higher both in students who took vitamin D (odds ratio (OR)=7.2, 95% confidence interval (CI)=1.8-29.9, P=0.006) or multivitamin supplements (OR=6.9, 95% CI=1.7-27.3, P=0.006) within 1 year. Students with a history of vitamin D testing >1 year before the study or moderate/vigorous physical activity (PA) had 4.4 (OR=4.4, 95% CI=1.7-11.4, P=0.003) and 2.7-fold (OR=2.7, 95% CI=1.3-5.3, P=0.006) higher odds of having 25(OH)D levels ⩾ 30 nmol/l, respectively. There was no significant association between 25(OH)D serum levels and average time spent outdoors per day (P=0.369) and type of clothing (long-sleeved vs short-sleeved; P=0.800).

CONCLUSIONS

Vitamin D deficiency was highly prevalent in Saudi medical students. Modifiable factors such as vitamin D intake and PA could be targeted for intervention. Further studies with standardized laboratory measurements of 25(OH)D are needed to explore the role of vitamin D testing in behavioral change, which may lead to increased serum 25(OH)D levels.