Vitamin D status in South Korean population: Seven-year trend from the KNHANES

An error in concept and definition of recommended dietary allowance developed in 1941: Time to create new ones

The recommended dietary allowance (RDA) for vitamin C differs greatly (40-110 mg/d) across countries. In addition, vitamin D deficiency is, effectively, a pandemic, with a prevalence of approximately 25% to 80% across countries according to the findings in the recent scientific literature. However, these phenomena are attributable to a serious error in the concept and definition of RDA, which was developed in 1941. The current definition of RDA is the average daily dietary nutrient intake level that is deemed sufficient to meet the nutrient requirements of almost all (97-98%) healthy individuals. This is an extremely high intake level for a specific nutrient affecting only a few individuals (the upper 2.5%) of the generally healthy population. The RDA should be redefined by investigating at which intake level of a specific nutrient the incidence of a specific disease or mortality increases or decreases based on prospective cohort studies.

Effect of sunlight on vitamin D and hemoglobin levels among the residents of Ningbo, China

Introduction

Objective: this study investigated the effect of sunlight on vitamin D and hemoglobin levels among the residents of Ningbo, China. The impact of gender, age, and season on vitamin D and hemoglobin levels was also explored. Methods: a total of 8,481 research subjects, including 5,146 men and 3,335 women, who were permanent residents of Ningbo and received health checkups at Ningbo Second Hospital, were included in the study. Ningbo City climate bulletin data from 2019 to 2022 was also included. Results: the study subjects received an average of 132.20 ± 40.05 h of sunlight exposure per month and had average vitamin D levels of 19.63 ± 6.61 ng/ml. Hemoglobin levels were adequate in 85.4 % of the participants and deficient in 14.6 %. Sunlight exposure correlated positively with vitamin D and negatively with hemoglobin levels. Regression analysis indicated that gender, age, and season affected vitamin D and hemoglobin levels to different degrees. Conclusion: in Ningbo, vitamin D deficiency was common in adults while hemoglobin levels were mostly normal. The amount of sunlight exposure had a significant effect on vitamin D and hemoglobin levels and this relationship was impacted by gender, age, and season.

Association between Vitamin D Deficiency and Serologic Response to Hepatitis B Virus Vaccination among Heavy Industry Workers

INTRODUCTION

Hepatitis B virus (HBV) vaccination has decreased the overall incidence of HBV infection; however, approximately 5 to 10% of people are non-responders to the vaccination. This study investigated the factors associated with non-response to HBV vaccination, with an emphasis on vitamin D deficiency (VDD).

METHODS

This retrospective observational study focused on adult workers in a single heavy industry. Individuals with negative initial hepatitis B surface antibody (anti-HBs) levels prior to vaccination and who then received a two- or three-dose series of HBV vaccinations were enrolled. The study endpoint was failure to achieve a seroprotective antibody response, defined as an anti-HBs titer less than 10 mIU/mL. Propensity score matching (PSM) and binary logistic regression models were used to adjust the outcomes for other clinical characteristics.

RESULTS

Among 760 workers, 566 (74.5%) exhibited VDD. The non-response rates to HBV vaccination were 13.4% (76/566) and 5.7% (11/194) among workers with and without VDD, respectively (p = 0.005). Even after adjustment using PSM, VDD was still associated with a higher rate of response failure (adjusted odds ratio 2.74; 95% confidence interval 1.40-5.38, p = 0.003). The binary logistic regression model showed that VDD, older age, omission of the third vaccine dose, lower initial anti-HBs titer, and current smoking were associated with response failure.

CONCLUSIONS

Our study suggests that VDD may impair the serologic response following HBV vaccination. Further research is needed to evaluate the effectiveness of vitamin D supplementation in increasing the response to HBV vaccination.

Determining the vitamin D supplementation duration to reach an adequate or optimal vitamin D status and its effect on blood lipid profiles: a longitudinal study

BACKGROUND

Recently, Serum vitamin D (Vit. D) levels evaluation and the use of Vit. D supplements have increased substantially. There is no specific guideline for the duration of Vit. D supplementation, so yet Vit. D supplementation duration has remained a critical and controversial issue. This study aimed to determine the vit. D supplementation duration to reach an adequate or optimal Vit. D status and its effect on lipid profile.

METHODS

In this longitudinal study, 345 women with different status of Vit. D levels were enrolled and followed up for one year. Eligible participants received 50,000 IU Vit. D3 (cholecalciferol) once a month for 12 consecutive months. The serum Vit. D levels and lipid profiles were measured at baseline, 3rd, 6th, and 12th months after the intervention. Participants were categorized based on Vit. D level at baseline into deficiency (< 20 ng/mL), inadequate (20-30 ng/mL), and adequate (> 30 ng/mL) groups, and the data were compared at different times between the three groups.

RESULTS

Three deficiency (n = 73), inadequate (n = 138) and adequate (n = 134) groups of participants were followed. In all participants the average amount of Vit. D level changes were 8 ng/mL after one year of supplementation. The mean changes of serum Vit. D level in 6th and 12th months vs. 3th month was as below: In deficiency group: 4.08 ± 0.85 and 10.01 ± 1.02 ng/mL; (p < 0.001), in inadequate group: 3.07 ± 0.59 and 7.26 ± 0.78 ng/mL; (p = 0.001) and in adequate group: 2.02 ± 0.88 and 6.44 ± 1.005 ng/ml; (p = 0.001). Lipid profiles were improved in three groups. So, the mean changes of lipid profiles at the end of the study comparing with the baseline were: -5.86 ± 2.09, -7.22 ± 1.43 and - 6.17 ± 1.72 (mg/dl) for LDL (p < 0.05); -12.24 ± 3.08, -13.64 ± 3.21 and - 17.81 ± 2.94 (mg/dl) for cholesterol (p < 0.05) in deficiency, inadequate and adequate groups, respectively. For triglyceride, the mean changes were - 13.24 ± 5.78 and - 15.85 ± 7.49 (mg/dl) in deficiency and adequate groups, respectively (p < 0.05). Although the triglyceride decreased in the inadequate group at the end of the study but this difference was not significant (p = 0.67).

CONCLUSION

Taking of 50,000 IU Vit. D 3 monthly for 12 months resulted in reaching its level to adequate level in both deficiency and insufficient groups; however, in the adequate group its level did not reach above than 50 ng/mL. Therefore, 50,000 IU Vit. D3 supplementation monthly for one year can have beneficial effects on lipid profiles and there is no risk of toxicity in healthy women.

Assessment of serum vitamin D levels in children aged 0-17 years old in a Chinese population: a comprehensive study

Vitamin D deficiency and insufficiency pose global public health challenges, yet research on serum vitamin D levels in the 0-17-year-old age group in southeastern China remains limited. This study aimed to fill this gap by investigating serum 25(OH)D levels in children in the region aged 0-17 years, contributing crucial data for understanding vitamin D nutritional status. Liquid chromatography‒mass spectrometry/mass spectrometry (LC‒MS/MS) technology was used. Vitamin D testing was integrated into routine diagnostic procedures for 11,116 children in Wujiang District, Suzhou City. Among the 0-17-year age group, comprising 6348 boys and 4768 girls, the prevalence of serum 25(OH)D deficiency and insufficiency was 21.4% and 31.0%, respectively. The median serum 25(OH)D concentration was 29.72 ng/mL (21.84-39.84 ng/mL) in boys compared to 28.48 ng/mL (20.65-39.23 ng/mL) in girls. Seasonal variations were observed, with median serum 25(OH)D concentrations of 29.02 ng/mL (20.73-39.72 ng/mL) in spring, 28.79 ng/mL (21.53-39.37 ng/mL) in summer, 30.12 ng/mL (22.00-39.70 ng/mL) in autumn, and 28.58 ng/mL (19.97-39.46 ng/mL) in winter. Statistically significant differences were noted in the serum 25(OH)D levels during autumn and winter. In conclusion, the rate of adequate vitamin D levels in local children was 47.5%, revealing a relatively high prevalence of vitamin D deficiency (21.4%) and insufficiency (31.0%), especially during the post-preschool period. Advocating for vitamin D supplementation in children is crucial for ensuring adequate vitamin D support.

Selective estrogen receptor modulators (SERMs) with vitamin D composite agent can prevent fracture better than SERMs treatment: based on the National Health Claims Database 2017-2019

With the analysis of nationwide health claim data, treatment with the composite agent of SERMs and vitamin D reduces the risk of osteoporotic fracture and hip fracture better compared to SERMs treatment in women with osteoporosis aged ≥ 50 years.

PURPOSE

This study compared the potential of the composite agent of selective estrogen receptor modulators (SERMs) and vitamin D (SERM + VitD) with that of SERMs-only for fracture prevention and mortality reduction in women aged ≥ 50 years.

METHODS

The incidence of osteoporotic fracture (fractures of the vertebrae, hip, wrist, or humerus) and all-cause death after treatment with SERM + VitD and SERMs were characterized using the Korean National Health Insurance Service database 2017-2019. The participants were divided into two groups (SERM + VitD vs SERMs). After exclusion and propensity score matching, 2,885 patients from each group were included in the analysis. Fracture incidence was compared between groups. Kaplan-Meier curves were used to compare mortality. Cox proportional hazards regression analysis was used to compare the risks of fracture occurrence and mortality between the groups.

RESULTS

The incidence rate (138.6/10,000 vs. 192.4/10,000 person-years), and risk of osteoporotic fractures (hazard ratio [HR], 0.77; 95% confidence interval [CI], 0.61-0.97; p = 0.024) were lower in the SERM + VitD group than in the SERMs group. Analysis for specific fractures showed a lower hazard of hip fracture in the SERM + VitD group (HR, 0.25; 95% CI, 0.09-0.71; p = 0.009). No difference was observed between the groups regarding mortality.

CONCLUSION

The risk of osteoporotic fractures, especially hip fractures, was lower in the SERM + VitD group than in the SERMs group. Therefore, the composite agent of SERMs and vitamin D can be considered as a viable option for postmenopausal women with a relatively low fracture risk.

Prevalence of vitamin D deficiency and its association with cardiometabolic risk factors among healthcare workers in the Eastern Cape province, South Africa; cross-sectional study

This study assesses the prevalence of Vitamin D deficiency and its potential association with cardiometabolic risk factors among South African adults residing in the Eastern Cape province. In this cross-sectional study, 1244 healthcare workers (HCWs) completed a self-administered questionnaire and venous blood samples were drawn at two academic hospitals in the Eastern Cape. History of hypertension and diabetes mellitus were self-reported. Participants were categorised as obese if their body mass index (BMI) ≥ 30 kg/m2. Participants were classified as having metabolic syndrome if they had hypertension, diabetes mellitus and obesity. Vitamin D [25(OH)D] deficiency was defined as venous blood concentrations < 50 nmol/L. Associations between vitamin D deficiency and participants' characteristics were assessed using multivariate logistic regression model analysis. The prevalence of vitamin D deficiency was 28.5% (n = 355), of whom 292 were female. Among the participants who were deficient in vitamin D, the prevalence of obesity, diabetes mellitus, hypertension, chronic kidney disease, and metabolic syndrome was 64.9% (n = 230), 9% (n = 32), 16.6% (n = 59), 2.3% (n = 8) and 18% (n = 64), respectively. In the adjusted multivariate logistic regression model, black Africans (AOR = 2.87; 95% CI 1.52-5.43) and individuals ≥ 42 years (AOR = 1.37; 95% CI 1.07-1.77) were more likely to exhibit vitamin D deficiency. However, there was no significant association by age, sex, and cardiometabolic markers. More than one in four healthcare workers was deficient in vitamin D among the study sample, especially the black Africans and older individuals. Further studies are needed at the population level to elucidate on the vitamin D status in the region.

Vitamin D Status and Reference Intervals Measured by Liquid Chromatography-Tandem Mass Spectrometry for the Early Adulthood to Geriatric Ages in a South Korean Population during 2017-2022

This study aimed to describe the latest 25-hydroxyvitamin D (25(OH)D) status of the South Korean population aged ≥ 20 years using 25(OH)D concentrations measured by liquid chromatography-tandem mass spectrometry and to determine the factors associated with total 25(OH)D concentrations. This cross-sectional, retrospective study consecutively selected 119,335 subjects with a median age of 57 (20-101) years who underwent health checkups among 13 Korean cities during 2017-2022. The total 25(OH)D concentration was 54.5 ± 24.0 nmol/L (mean ± SD). The 7.6%, 47.5%, and 82.9% of participants had 25(OH)D less than 25, 50, and 75 nmol/L, respectively. The prevalence of 25(OH)D deficiency (<25 nmol/L) was higher in females than in males (8.9% vs. 6.1%) and varied between age groups, decreasing in older subjects. Those aged 20-29 years had the highest prevalence of 25(OH)D deficiency (23.0% in females and 20.1% in males), which also varied between cities. In the adjusted model, female sex, older age, summer and autumn seasons, lower body mass index (<25 kg/m2), and lower high-sensitivity C-reactive protein concentration (<1 mg/L) were associated with higher total 25(OH)D concentrations. This study could provide an exact understanding of the status of vitamin D and help devise strategies to prevent vitamin D deficiency among the Korean population.

Geographic location and ethnicity comprehensively influenced vitamin D status in college students: a cross-section study from China

BACKGROUND

Vitamin D plays an important role in the health of adolescents, whereas vitamin D status of Chinese college students was seldom studied in China. To explore the vitamin D status and its relationship with ethnicity and geographic location in Chinese college students.

METHODS

The freshmen were taken a physical examination by trained medical personnel after they reported to university. Demographic information including age, gender, ethnicity, region of original residence was collected using a questionnaire survey. Serum 25(OH)D3 concentrations were measured using a liquid chromatograph mass spectrometer. Multiple regression analyses were used to explore the factors that influence serum 25(OH)D3 levels.

RESULTS

Totally 3220 freshmen who came from 26 provinces, autonomous districts or municipalities were recruited, with a mean age of 18.75 ± 1.18 years and 70.2% of them were female. The mean serum 25(OH)D3 levels were 18.51 ± 6.54 ng/mL, and the proportion of vitamin D deficiency (< 20 ng/mL) and insufficiency (20 ~  < 30 ng/mL) was 64.4% and 30.2%, respectively. The combined proportion of vitamin D deficiency and insufficiency was increased with the latitude increased. Miao had the highest serum 25(OH)D3 levels, whereas Kazak ethnic had the lowest (22.51 ng/mL vs. 13.94 ng/mL) among different ethnic groups. Female students, students from city, Uighur and Kazak ethnic, residing in high latitude was significantly associated with lower serum 25(OH)D3 levels (P < 0.05).

CONCLUSIONS

Vitamin D deficiency is an important health problem in Chinese college students. Sunlight activities, dietary and life-style intervention for college students according to geographic location and ethnicities should be considered.

Update on vitamin D status in sunshine-abundant Thailand, 2019-2020

OBJECTIVE

The prevalence of vitamin D deficiency worldwide remains unknown. In the Thai 4th National Health Examination Survey (2008-2009) cohort, ∼45% and 7% of the adult population had serum 25-hydroxyvitamin-D [25(OH)D] levels below the threshold of 75 and 50 nmol/L, respectively. Vitamin D has been a hot topic in the scientific community. The aim of this study was to uncover the current situation regarding vitamin D status in Thailand.

METHODS

Participants were 4098 adults ages 10 to 96 y, randomly selected from the Thai 6th National Health Examination Survey (2019-2020) cohort. Serum 25(OH)D levels were measured by liquid chromatography/tandem mass spectrometry. Data were expressed as mean ± SE and adjusted odds ratio (95% CI).

RESULTS

Mean vitamin D status based on serum 25(OH)D was 88.2 nmol/L and differed by age, sex, residency, and religion. The prevalence of serum 25(OH)D <75 and <50 nmol/L were 31% and 4%, respectively. The prevalence of vitamin D deficiency was lower in individuals who lived in the northeastern part of Thailand or were male. The risk for vitamin D deficiency was lower than that in 2009. In multiple linear regression analysis, female sex, younger age, urbanization, a higher body mass index, Muslim religion, and living in Bangkok or the central region of Thailand were independently associated with lower serum 25(OH)D levels.

CONCLUSIONS

The vitamin D status in the Thai population has improved over the past 10 y. This improvement may reflect an increased awareness related to adequate vitamin D status.

Discordance in Secular Trends of Bone Mineral Density Measurements in Different Ages of Postmenopausal Women

BACKGROUND

Age-adjusted bone mineral density (BMD) in postmenopausal women decreases in developed countries whereas incidence of osteoporotic fracture decreases or remains stable. We investigated secular trends of bone density from 2008 to 2017 among different age groups of postmenopausal women.

METHODS

We analyzed BMD data obtained from health check-ups of 4,905 postmenopausal women during three survey cycles from 2008 to 2017. We divided them into 3 groups by age (50-59 years, 60-69 years, and 70 years or more) and observed the transition of lumbar and femoral BMD in each group, before and after adjusting for variables that may affect BMD.

RESULTS

Age-adjusted BMD, bone mineral content (BMC), and T-score demonstrated a declining trend over the survey period at lumbar spine (-2.8%), femur neck (-3.5%) and total femur (-4.3%), respectively. In the analysis for the age groups, the BMD, BMC, and T-score presented linear declining trend (-6.1%) in younger postmenopausal women while women aged over 70 or more showed linear increasing trends (+6.3%) at lumbar spine during the survey period. Femoral neck and total femur BMD demonstrated a declining linear trend only in the 50-59 and 60-69 years groups (-5.5%, -5.2%, respectively), but not in the 70 years or more group.

CONCLUSION

BMD in younger postmenopausal women has decreased considerably but has increased or plateaued in elderly women. This discordance of BMD trends among different age groups may contribute to decreased incidence of osteoporotic fracture despite a recent declining BMD trend in postmenopausal women.

Monthly versus daily administration of vitamin D3 in children: a retrospective propensity score-matched study

Objectives

We aimed to evaluate the efficacy and safety of monthly vitamin D3 administration compared to a daily dosing regimen in healthy children with vitamin D deficiency.

Methods

This retrospective study included vitamin D deficient (serum 25-hydroxyvitamin D [25(OH)D] < 20 ng/mL) children with precocious puberty who received gonadotropin-releasing hormone agonist every 4 weeks between December 2019 and November 2022. We used propensity scores to 1:1 match daily (1,000 IU daily) and monthly (25,000 IU per 4 weeks) administration of vitamin D3 based on age, sex, body mass index Z-scores, season of blood collection, and baseline serum 25(OH)D concentrations.

Results

Of 299 children, 192 were matched based on propensity scores (126 girls and 66 boys, 10.5 ± 1.4years). After a mean follow-up of 5.9 months (standard deviation [SD] 2.5 months), the monthly group showed a statistically significant increase in serum 25(OH)D concentrations (10.9 ± 5.3 vs. 8.2 ± 7.2 ng/mL; p = 0.018), higher corrected dose-response (12.3 ± 5.9 vs. 8.2 ± 7.2 ng/mL increase per 1,000 IU daily; p = 0.002), and a higher proportion of patients attaining 25(OH)D > 20 ng/mL (78.1% vs. 58.3%,; p=0.005) compared with the daily group. No cases of hypercalcemia were observed in either group.

Conclusions

Monthly administration of vitamin D3 may be an effective and safe alternative to correct hypovitaminosis D in pediatric population, possibly attributed to enhanced compliance.

Influence of Vitamin D Deficiency on the Expression of Genes and Proteins in Patients With Medium Rotator Cuff Tears

BACKGROUND

Whether vitamin D deficiency is related to rotator cuff muscle and tendon physiology is controversial.

PURPOSE

To assess the relationship between vitamin D deficiency and various gene expression patterns in patients with rotator cuff tears.

STUDY DESIGN

Controlled laboratory study.

METHODS

During arthroscopic surgery, samples from the supraspinatus muscle, deltoid muscle, and supraspinatus tendon were acquired from 12 patients with vitamin D deficiency (serum 25-hydroxyvitamin D concentration <20 ng/dL) and 12 patients with sufficient vitamin D levels (control group, serum 25-hydroxyvitamin D concentration ≥30 ng/dL) who were matched for age, sex, and tear size. Alterations in the expression of genes and proteins associated with myogenesis, muscle atrophy, adipogenesis, inflammation, and apoptosis, as well as in vitamin D receptor expression, were assessed using quantitative reverse transcription polymerase chain reaction, Western blotting, and immunohistochemistry and were compared between the 2 groups.

RESULTS

Vitamin D receptor gene expression in the deltoid muscle was significantly lower in the vitamin D deficiency group than in the control group (P = .043). Additionally, in the deltoid muscle, myoDgene expression levels were lower and atrogin levels were higher in the vitamin D deficiency group than in the control group (P = .034 and P = .011, respectively). However, in the supraspinatus muscle, no differences were observed between groups in the expression of myogenesis- or atrophy-related genes (all P > .05). The expression of inflammation-related genes (interleukin (IL)-1β and IL-6) was significantly higher in the vitamin D deficiency group, in both the deltoid and supraspinatus muscles (all P < .05). The supraspinatus tendon tissue did not show any significant differences in any gene expression evaluated (all P > .05). A correlation between gene and protein expression was observed for atrogin and IL-1β in the deltoid muscle (P = .019 and P = .037, respectively) and for IL-6 in the supraspinatus muscle (P = .044).

CONCLUSION

Vitamin D deficiency was not associated with the expression of myogenesis-related or muscle atrophy-related genes in the supraspinatus muscle of patients with rotator cuff tears, unlike in the deltoid muscle; rather, vitamin D deficiency was associated with increased proinflammatory cytokine expression.

CLINICAL RELEVANCE

In patients with rotator cuff tears, vitamin D deficiency was observed to be associated with increased levels of proinflammatory cytokines in the rotator cuff muscles, without significant changes in gene expression related to myogenesis or muscle atrophy.

Estimated dietary vitamin D intake and major vitamin D food sources of Koreans: based on the Korea National Health and Nutrition Examination Survey 2016-2019

BACKGROUND/OBJECTIVES

The purpose of this study was to establish a database (DB) of foods containing vitamin D that were investigated in the Korea National Health and Nutrition Examination Survey (KNHANES), to estimate the dietary vitamin D intake, to evaluate the dietary adequacy of this intake, and to identify the major food sources of Koreans that contain vitamin D.

SUBJECTS/METHODS

This study used data from the KNHANES 2016-2019. Individuals aged ≥ 1 year who participated in the nutrition survey (n = 28,418) were included. The dietary intake was assessed by the 24-h dietary recall method and individual dietary vitamin D intake was estimated using a newly established vitamin D DB. Dietary adequacy was evaluated by comparing the dietary intake of the participants with adequate intake (AI) as defined by Dietary Reference Intakes for Koreans (KDRIs) 2020.

RESULTS

The average dietary vitamin D intake for all the subjects was 3.13 μg/d, which was 33.1% of AI. Dietary vitamin D intake was lower in rural residents, the elderly, and those with low income. The major food groups that contributed to the total dietary vitamin D intake were fish and shellfish (61.59%), eggs (17.75%), meat (8.03%), milk (4.25%), legumes (3.93%), and grains (3.84%). The top 10 individual food items that contributed to the total vitamin D intake were eggs (17.44%), squid (8.5%), eels (7.44%), salmon (5.35%), mackerel (5.27%), anchovies (4.65%), yellow croakers (4.58%), pork meat (4.47%), soymilk (4.46%), and skipjack tuna (3.80%).

CONCLUSION

These results show that the mean dietary vitamin D intake of Koreans is lower than the reference AI level. Nutritional policies need to be put in place to increase the vitamin D intake of Koreans in the future. In addition, comprehensive research on all the sources of vitamin D, including intake of supplements and biosynthesis in the skin, is required.

Effects of intermittent or single high-dose vitamin D supplementation on risk of falls and fractures: a systematic review and meta-analysis

Previous randomized controlled trials have reported inconsistent findings regarding the effects of high-dose vitamin D supplementation on a risk of falls and fractures. This meta-analysis of 15 trials shows that intermittent or single high-dose vitamin D supplementation had no preventive effect on the risk of falls and fractures and might even increase the risk of falls.

PURPOSE

Randomized controlled trials (RCTs) have reported controversial findings regarding the associations between intermittent or single high-dose vitamin D supplementation and a risk of falls and fractures in adults. This study aimed to investigate those associations using a systematic review and meta-analysis.

METHODS

We searched PubMed, EMBASE, and Cochrane Library from inception to May 25, 2022. Data were extracted for a random-effects meta-analysis to calculate a pooled relative risk (RR) with a 95% confidence interval (CI).

RESULTS

Out of 527 articles, a total of 15 RCTs were included in the final analysis. In a meta-analysis of RCTs, intermittent or single high-dose vitamin D supplementation showed no significant beneficial effect in the prevention of either falls (RR, 1.03 [95% CI, 0.98-1.09]; I² = 56.6%; n = 11) or fractures (RR, 0.99 [95% CI, 0.87-1.14]; I² = 48.3%; n = 11). Among the subgroup meta-analyses by various factors, intermittent or single high-dose vitamin D supplementation reduced the risk of fractures in the subgroup meta-analysis of RCTs that included fewer than 1000 participants (RR, 0.74 [95% CI 0.57-0.96]; I² = 0.0%; n = 5). However, its beneficial effect was not observed in those including 1000 or more participants (RR, 1.06 [95% CI 0.92-1.21]; I² = 57.5%; n = 6). In contrast, intermittent or single high-dose vitamin D3 supplementation increased the risk of falls on the borderline of statistical significance (RR, 1.06 [95% CI 0.99-1.15]; P = 0.051; I² = 50.0%; n = 7).

CONCLUSIONS

Intermittent or single high-dose vitamin D supplementation had no preventive effect on the risk of falls and fractures and might even increase the risk of falls.

Metabolomic analysis of the inhibitory effect of phthalates and bisphenol A on the antioxidant activity of vitamin D in human samples using liquid chromatography–mass spectrometry

Vitamin D is important because it has roles in maintaining musculoskeletal health, redox homeostasis, and the immune system; however, it is commonly dysregulated by endocrine disrupting chemicals, particularly phthalates and bisphenol A (BPA). Continuous exposure to phthalates and BPA may alter the endogenous metabolite profiles associated with vitamin D activity, although the specific metabolites are yet to be identified. In this study, we identified the endogenous metabolites altered by phthalates and BPA exposure through untargeted metabolic profiling and investigated the role of these metabolites in vitamin D activity. Plasma metabolic profiling using liquid chromatography-mass spectrometry was performed in two groups: severe 25-hydroxyvitamin D (25(OH)D) deficiency and high exposure to phthalates and BPA (Group A) and 25(OH)D deficiency and low exposure to phthalates and BPA (Group B). Multivariate analysis revealed a distinct separation between the two groups. A total of six metabolites were annotated, of which levels of two were significantly different between the two groups: platelet-activating factor (PAF) C16 or lysophosphatidylcholine (lysoPC) 18:0, and 11Z-eicosenamide. Plasma levels of PAF C16 or lysoPC 18:0 were increased in Group A and exhibited an area under the curve of 0.769 with an accuracy of 74.4% in a receiver operating characteristic curve analysis. These metabolites are generated as byproducts of lipid peroxidation, which supports the fact that phthalates and BPA induce oxidative stress in cells. Furthermore, PAF C16 and lysoPC 18:0 may be involved in the network that interferes with the antioxidant activity of vitamin D upon exposure to phthalates and BPA. This study results provide useful information on how the activity of vitamin D on the antioxidant system is inhibited when exposure to phthalates and BPA.

Serum 25-hydroxyvitamin D status of a large Chinese population from 30 provinces by LC-MS/MS measurement for consecutive 3 years: differences by age, sex, season and province

PURPOSE

We aimed to describe the vitamin D status and its distribution in different age groups, sexes, seasons, and provinces of a large Chinese population.

METHODS

This study retrospectively analyzed 1,528,685 results of serum 25-hydroxyvitamin D (25(OH)D) in the central laboratory of KingMed Diagnostics. The samples were from the individuals aged 0-119 years old in 30 provinces of China. Serum 25(OH)D was measured by an accurate commercial liquid chromatography-tandem mass spectrometry (LC-MS/MS) method from January 2017 to December 2019. The subjects were stratified by age, sex, the season of blood collection, and the province of residence.

RESULTS

The median 25(OH)D concentration was 25.5 ng/mL (interquartile range (IQR) 18.7-32.7 ng/mL) in males and 20.8 ng/mL (IQR 14.4-28.2 ng/mL) in females. Overall, the median 25(OH)D concentration decreased with age in both males and females. Males had a 0.2-2.4 ng/mL higher median 25(OH)D concentration than females in different age groups. Vitamin D deficiency (25(OH)D < 15 ng/mL for the individuals under 14 years old; < 20 ng/mL for the individuals over 14 years old) was found in 21.3% of males and 43.6% of females. Significant seasonal variation of serum 25(OH)D concentrations was repeatedly observed in 3 years, with median concentration higher in summer (25.3 ng/mL (IQR 19.3-31.9 ng/mL)) and lower in winter (18.5 ng/mL (IQR 12.3-26.6 ng/mL)). Vitamin D status varied by province. The median 25(OH)D concentration was the highest in Hainan (31.0 ng/mL (IQR 24.9-39.2 ng/mL)) and the lowest in Qinghai (14.4 ng/mL (IQR 9.6-20.0 ng/mL)). 25(OH)D₂ was detected in 12.2% of the results, and no significant seasonal variation was observed.

CONCLUSION

In China, vitamin D deficiency is prevalent in the population participating in clinical vitamin D measurement. Age and sex differences in vitamin D levels were observed in our study. Seasonal variation and provincial differences are important aspects of serum vitamin D status. 25(OH)D₂ cannot be ignored entirely in clinical measurement practice in China.

Effect of vitamin D deficiency on metabolic syndrome among Korean shift workers

OBJECTIVE

This study aimed to investigate the effect of vitamin D deficiency on metabolic syndrome among shift workers.

METHODS

This study included 207 756 workers who underwent a comprehensive health examination at a large South Korean university hospital between 2012 and 2018. We performed multivariate-adjusted logistic regression analysis and analyzed mediation and exposure-mediator interaction.

RESULTS

Overall, 5.5% of the participants had metabolic syndrome. Compared to day work, the odds ratios (OR) of metabolic syndrome and vitamin D deficiency (<12 ng/mL) for shift work were 1.14 [95% confidence interval (CI) 1.06-1.22] and 1.63 (95% CI 1.57-1.70), respectively. Among shift workers, the OR of metabolic syndrome for vitamin D levels of 12-20 and <12 ng/mL, compared with a level of ≥20 ng/mL, were 1.36 (95% CI 1.15-1.61) and 1.51 (95% CI 1.26-1.81), respectively. Shift work and vitamin D deficiency showed an additive interaction; the relative excess risks due to interaction, attributable proportion, and synergy index were 0.26 (95% CI 0.08-0.44), 0.17 (95% CI 0.07-0.28), and 2.09 (95% CI 1.23-3.55), respectively. When vitamin D deficiency was treated as a mediator, the direct and total effects of shift work on metabolic syndrome were 1.12 (95% CI 1.04-1.22) and 1.15 (95% CI 1.07-1.25), respectively. The indirect effect was 1.03 (95% CI 1.02-1.04) and accounted for 18% of the total effect.

CONCLUSION

Vitamin D is a potential mediator of the impact of shift work on metabolic risk factors.

Serum 25-Hydroxyvitamin D concentrations are inversely associated with all-cause mortality among Koreans: a nationwide cohort study

Evidence on the association between serum 25-hydroxyvitamin D (25(OH)D) concentration and all-cause and cause-specific mortality in Asians, especially Koreans, is limited. We hypothesized that high concentrations of 25(OH)D are associated with lower all-cause and cause-specific mortality in the general Korean population. This study included 27,846 adults participating in the Fourth and Fifth Korean National Health and Nutrition Examination Survey 2008-2012, followed up through December 31, 2019. Hazard ratios (HR) and 95% confidence intervals (CIs) for mortality from all causes, cardiovascular disease (CVD), and cancer were estimated using multivariable-adjusted Cox proportional hazards regression. The weighted mean serum 25(OH)D of study participants was 17.77 ng/mL; 66.5% had vitamin D deficiency (<20 ng/mL) and 94.2% had insufficient vitamin D (<30 ng/mL). During a median follow-up of 9.4 years (interquartile range, 8.1-10.6 years), 1680 deaths were documented, including 362 CVD deaths and 570 cancer deaths. Serum 25(OH)D levels ≥30 ng/mL were inversely associated with all-cause mortality (HR, 0.57; 95% CI, 0.43-0.75) compared with serum 25(OH)D levels <10 ng/mL. Based on the quartile cutoffs of serum 25(OH)D concentration, the highest quartile of serum 25(OH)D concentration (≥21.8 ng/mL) was associated with the lowest all-cause mortality (HR, 0.72; 95% CI, 0.60-0.85; P trend < .001), and CVD mortality (HR, 0.60; 95% CI, 0.42-0.85; P trend = .006). No association with cancer mortality outcome was found. In conclusion, higher serum 25(OH)D levels were associated with lower all-cause mortality in the general Korean population. An additional association was found between higher quartile of serum 25(OH)D and lower CVD mortality.

Vitamin D Status of People 3 to 79 Years of Age from the Canadian Health Measures Survey 2012-2019

BACKGROUND

Vitamin D is recognized in bone health and the prevention of rickets and osteomalacia.

OBJECTIVE

This study aimed to assess vitamin D status of people in Canada and to identify factors associated with vitamin D inadequacy and deficiency.

METHODS

Serum 25-hydroxyvitamin D (25(OH)D) from the Canadian Health Measures Survey (cycles 3-6, n = 21,770, 3-79 y) were evaluated for geometric means and proportions <40 (inadequate) and <30 (risk of deficiency) nmol/L. Factors associated with inadequacy or deficiency were tested using logistic regression.

RESULTS

Mean serum 25(OH)D was 57.9 (95% CI: 55.4, 60.5) nmol/L; the prevalence of inadequacy was 19.0% (95% CI: 15.7, 22.3) and risk of deficiency was 8.4% (95% CI: 6.5, 10.3). Prominent dietary factors associated with inadequacy in adults included: not consuming fish compared with ≥1/wk (adjusted OR_adj: 1.60; 95% CI: 1.21, 2.11), none compared with ≥1/d for cow's milk (OR_adj: 1.41; 95% CI: 1.02, 1.94) or margarine (OR_adj: 1.42; 95% CI: 1.08, 1.88); or nonuser compared with user of vitamin D supplements (OR_adj: 5.21; 95% CI: 3.88, 7.01). Notable demographic factors included: younger adults compared with 71 to 79 y (19-30 y OR_adj: 2.33; 95% CI: 1.66, 3.29); BMI ≥30 compared with <25 kg/m² (OR_adj: 2.30; 95% CI: 1.79, 2.95); lower household income quartile 1 compared with 4 (OR_adj: 1.46; 95% CI: 1.00, 2.15); and self-reported Black (OR_adj: 8.06; 95% CI: 4.71, 13.81), East/Southeast Asian (OR_adj: 3.83; 95% CI: 2.14, 6.85), Middle Eastern (OR_adj: 4.57; 95% CI: 3.02, 6.92), and South Asian (OR_adj: 4.63; 95% CI: 2.62, 8.19) race compared with White. Similar factors were observed in children and for deficiency.

CONCLUSIONS

Most people in Canada have adequate vitamin D status; nonetheless, racialized groups have an elevated prevalence of inadequacy. Further research is required to evaluate if current strategies to improve vitamin D status, including increasing vitamin D in fortified foods and supplements, and dietary guidance to include a source of vitamin D every day help to reduce health inequality in Canada.

The association between vitamin D deficiency and risk of renal event: Results from the Korean cohort study for outcomes in patients with chronic kidney disease (KNOW-CKD)

Backgrounds

Some observational studies have suggested a possible association between vitamin D deficiency and CKD. However, in most studies, the causality between low levels of vitamin D and risk of renal events could not be explained. We investigated the relationship between vitamin D deficiency and risk of severe CKD stage and renal event in a large-scale prospective cohort study.

Methods

We used data from a prospective cohort of 2,144 patients with available information on serum 25-hydroxyvitamin D (25(OH)D) levels at baseline from KNOW-CKD, 2011-2015 were included. Vitamin D deficiency was defined as serum 25(OH)D levels < 15 ng/mL. We performed a cross-sectional analysis to elucidate the relationship between 25(OH)D and CKD stage using baseline CKD patient data. We further examined a cohort analysis to clarify the association between 25(OH)D and risk of renal event. Renal event was a composite of the first occurrence of a 50% decline in eGFR from the baseline value or the onset of CKD stage 5 (initiation of dialysis or kidney transplantation) across the follow-up period. We also investigated the associations of vitamin D deficiency with risk of renal event according to diabetes and overweight status.

Results

Vitamin D deficiency were significantly associated with an increased risk of severe CKD stage - 1.30-fold (95% CI: 1.10-1.69) for 25(OH)D. Deficiency of 25(OH)D with 1.64-fold (95% CI: 1.32-2.65) was related to renal event compared with the reference. Furthermore, vitamin D deficiency patients with presence of DM and overweight status also displayed higher risk than non-deficient patients for risk of renal event.

Conclusion

Vitamin D deficiency is associated with significantly increased risk of severe CKD stage and renal event.

Correlation between serum vitamin D level and benign paroxysmal positional vertigo recurrence

OBJECTIVE

Benign paroxysmal positional vertigo (BPPV) is the most common cause of dizziness in the general population. BPPV is known to be closely related to the serum vitamin D level. This study aimed to examine the relationship between serum vitamin D levels and BPPV recurrence.

METHODS

A retrospective chart review was conducted on 50 patients diagnosed with posterior and lateral canal BPPV. The diagnosis of BPPV was based on the finding of vertigo and nystagmus induced by certain head positions (The Dix-Hallpike maneuver and head roll tests). The patients were classified into BPPV recurrence (Group A) and non-recurrence groups (Group B). Otolith function was assessed by cervical vestibular evoked myogenic potential (cVEMP) and ocular vestibular evoked myogenic potential (oVEMP), and their association with vitamin D levels was evaluated.

RESULTS

There were 19 subjects in Group A and 31 in Group B. There were no significant differences in age, sex, cVEMP, and oVEMP between the two groups. The average vitamin D level was 12.9 ± 8.0 ng/mL for Group A and 19.2 ± 8.2 ng/mL for Group B, and the difference between the groups was significant (p = 0.011). In the receiver operating characteristic curve analysis for BPPV recurrence with the best sensitivity and specificity, the optimal cut-off value of total serum vitamin D was determined as 12.74 ng/mL. Furthermore, reclassifying the patients based on the cut-off value showed a significantly higher recurrence rate in the group with a lower serum vitamin D level (70.5% vs. 22.5%, p = 0.007).

CONCLUSION

This complex finding highlights the importance of measuring serum vitamin D levels to monitor and evaluate patients at risk of BPPV recurrence.

Inverse Relationship between Serum 25-Hydroxyvitamin D and Elevated Intraocular Pressure

Elevated intraocular pressure (EIOP) is the only major modifiable risk factor of glaucoma. While low serum vitamin D levels are considered a potential risk factor for glaucoma, there is conflicting evidence on the relationship between vitamin D and EIOP despite the possible linkage between vitamin D and intraocular pressure through oxidative stress and systemic inflammation. Therefore, the aim of this study is to verify the relationship between 25-hydroxyvitamin D [25(OH)D] and EIOP using data from 15,338 individuals who visited the health promotion center of an education hospital. The cubic spline curve revealed an inverse dose-dependent association between serum 25(OH)D level and EIOP. Using multiple logistic regression analysis, the fully adjusted odds ratio (OR) with 95% confidence interval (CI) for the EIOP of the serum 25(OH)D per increment was 0.97 (0.96-0.990). The fully adjusted ORs (95% CIs) for the EIOP of the 25(OH)D insufficiency and 25(OH)D sufficiency groups, compared to 25(OH)D deficiency group, were 0.72 (0.56-0.92) and 0.51 (0.34-0.78), respectively. The relationship remained significant in male and young age subgroups. In conclusion, the clinical assessment of intraocular pressure may prove helpful when treating patients with 25(OH)D deficiency, which may be a preventive strategy against the development of glaucoma.

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.

Changes in Vitamin D Status in Korean Adults during the COVID-19 Pandemic

The aim of this study was to investigate changes in 25(OH)D (25-hydroxyvitamin D) levels and in the vitamin D status of Korean adults before and during the coronavirus disease (COVID-19) pandemic. This study compared serum 25(OH)D levels before and after the pandemic in 1483 adults aged 19 years and older who were screened at a university hospital. Subjects were selected only from participants tested in the same season before and after the pandemic. The pre-COVID-19 testing period was from 1 March 2018 to 31 November 2019; the testing period in the COVID-19 era was from 1 June 2020 to 31 November 2021. The mean 25(OH)D level for all participants was 21.4 ± 10.2 ng/mL prior to the outbreak of COVID-19, which increased to 23.6 ± 11.8 ng/mL during the COVID-19 lockdown period (p < 0.001). The increase was particularly dramatic in elderly females (28.8 ± 12.3 ng/mL to 37.7 ± 18.6 ng/mL, p = 0.008). The prevalence of vitamin D deficiency decreased in both males (48.4% to 44.5%, p = 0.005) and females (57.0% to 46.0%, p < 0.001). In conclusion, 25(OH)D levels in Korean adults increased during the COVID-19 era, and the prevalence of vitamin D deficiency decreased accordingly.

Position Statement: Vitamin D Intake to Prevent Osteoporosis and Fracture in Adults

Adequate vitamin D status is essential for bone health. New randomized controlled trials investigating the effect of vitamin D supplementation on bone health have recently been published. This position statement updates and expands on the previous 2015 position statement of the Korean Society for Bone and Mineral Research on the adequate vitamin D status for healthy older adults (age ≥ 70 years) and those at high risk of osteoporosis and fracture (adults on osteoporosis medications) to maintain serum 25-hydroxy-vitamin D (25[OH]D) levels ≥ 20 ng/mL but < 50 ng/mL. A serum 25(OH)D level of 30 ng/mL may be beneficial for those on anti-resorptives. Vitamin D can be obtained from ultraviolet light exposure and diet. To reach the target vitamin D status through intake, adults must consume at least 400 IU/day to reach 20 ng/mL and 800 to 1,000 IU/day to reach 30 ng/mL. Foods familiar to the Korean diet that are high in vitamin D content or consumed frequently enough to positively impact vitamin D status are introduced in addition to the amount required to help reach one's target vitamin D status.

Assessing the effects of ultraviolet radiation, residential greenness and air pollution on vitamin D levels: A longitudinal cohort study in China

Vitamin D metabolism is essential in aging and can be affected by multiple environmental factors. However, most studies conducted single exposure analyses. We aim to assess the individual and combined effects of ultraviolet (UV) radiation, residential greenness, fine particulate matter (PM_2.5), and ozone (O₃) on vitamin D levels in a national cohort study of older adults in China. We used the 2012 and 2014 Chinese Longitudinal Healthy Longevity Survey data, and measured the environmental exposure in the same year. We interpolated the UV radiation from monitoring stations, measured residential greenness through satellite-derived Normalized Difference Vegetation Index (NDVI), modeled PM_2.5 with satellite data, and estimated O₃ using machine learning. We dichotomized serum 25-hydroxy vitamin D (25(OH)D), the primary circulating form of vitamin D, into non-deficiency (≥50 nmol/L) and deficiency (<50 nmol/L) categories. We used the generalized estimating equation for analysis, adjusted for sociodemographic information, lifestyle, physical condition, and season of blood draw, and calculated joint odds ratios based on the Cumulative Risk Index. We also explored the interaction between interested exposures, modification of participants' characteristics, and potential mediation. We included 1,336 participants, with a mean age of 83 at baseline. In single exposure models, the odds ratios of vitamin D deficiency (VDD) for per interquartile range increase in UV radiation, NDVI, PM_2.5, and O₃ and decrease were 0.39 (95 % CI:0.33,0.46), 0.90 (0.81,1.00), 1.65 (1.53,1.78), 1.67 (1.46,1.92), respectively. UV radiation mediated nearly 48 % and 78 % of the relationship between VDD and PM_2.5 and O₃, respectively. The association between UV radiation and VDD was stronger in females than men (OR: 2.25 vs 1.22). UV radiation, residential greenness can protect against VDD, while, PM_2.5 and O₃ increase the risk of VDD. UV radiation partly mediated the association between air pollution and VDD.

Prevalence of Vitamin D Insufficiency/Deficiency and Their Role in Atopic Dermatitis Development and Course in Children

Various conclusive evidence on the role of vitamin D in the pathogenesis of atopic dermatitis (AD) has been obtained in recent decades. Many studies have shown that patients with AD have low concentration of 25(OH)D in blood associated with high concentration of allergen specific IgE (according to several reports). The analysis of low 25(OH)D concentration prevalence, association of vitamin D deficiency with AD severity and sensitization to allergens, and association of vitamin D disorders with risk of AD development is presented.

Associations between ambient air pollution, obesity, and serum vitamin D status in the general population of Korean adults

Background

Although a growing body of evidence suggests air pollution is associated with low serum vitamin D status, few studies have reported whether obesity status affects this relationship. The aim of this study was to identify associations between ambient air pollution exposure, obesity, and serum vitamin D status in the general population of South Korea.

Methods

This study was conducted in a cross-sectional design. A total of 30,242 Korean adults from a nationwide general population survey were included for our final analysis. Air pollutants included particulate matter with an aerodynamic diameter ≤ 10 μm (PM₁₀), nitrogen dioxide (NO₂), and carbon monoxide (CO). We measured serum 25-hydroxyvitamin D concentration to assess vitamin D status for each participant. Multiple linear and logistic regression analyses were performed to identify associations between ambient air pollution and vitamin D status in each subgroup according to body mass index level.

Results

The annual average concentrations of PM₁₀, NO₂, and CO were significantly associated with a lower serum vitamin D concentration and higher risk of vitamin D deficiency. The results show a significant association between serum vitamin D status and PM₁₀ exposure in obese subgroup. Based on the gender, females with obesity showed more strong association (negative) between different air pollutants and low serum vitamin D concentration and a higher risk of vitamin D deficiency. However, this pattern was not observed in men.

Conclusions

This study provides the first evidence that women with obesity may be more vulnerable to vitamin D deficiency in the context of persistent exposure to air pollution.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-14164-y.

Association between lower parity and low muscle mass in postmenopausal women: data from KNHANES (2010-2011)

OBJECTIVE

This study aimed to investigate whether parity is associated with the prevalence of low muscle mass in postmenopausal women.

METHODS

This study was performed using data from the 2010-2011 Korean National Health and Nutrition Examination Survey, which included 1,338 postmenopausal women aged 46 to 70 years. The association between parity and low muscle mass was analyzed after adjusting parity, multiparity, age, body mass index, diabetes mellitus, education level, and Homeostatic Model Assessment of Insulin Resistance and using weighted multiple logistic regression analysis. Modifiable risk factors were evaluated in a susceptible population. Low muscle mass was defined as an appendicular skeletal muscle mass index below 2 SDs with a cutoff value of 5.45 kg/m 2 .

RESULTS

The low muscle mass group ( n = 343) had lower parity, lower body mass index, more frequent previous history of diabetes mellitus, higher Homeostatic Model Assessment of Insulin Resistance, and higher education level compared with the non-low muscle mass group ( n = 995). After adjusting for the confounding factors, parity with three births or more was associated with a significantly lower odds of postmenopausal low muscle mass than nulliparity (model 1: odds ratio, 0.32; 95% confidence interval, 0.12-0.87; P = 0.03; model 2: odds ratio, 0.27; 95% confidence interval, 0.11-0.67; P < 0.05). In the subgroup analysis of the lower parity group, moderate aerobic activity was associated with a lower low muscle mass prevalence.

CONCLUSIONS

A lower parity is associated with increasing the odds of low muscle mass in postmenopausal Korean women. Moderate aerobic activity may be effective in lowering the odds of low muscle mass in postmenopausal women with lower parity.

Cardiovascular risks associated with calcium supplementation in patients with osteoporosis: a nationwide cohort study

AIMS

This study aimed to evaluate the real effects of calcium supplementation on cardiovascular outcomes within a population-based cohort.

METHODS AND RESULTS

From a nationwide health screening database in South Korea, a total of 11 297 patients with osteoporosis who had taken calcium supplementation with or without vitamin D for at least 90 days [total calcium group; calcium supplementation only (CaO), n = 567; calcium supplementation in combination with vitamin D (CaD), n = 10 730] were matched at a 1:1 ratio to patients who had not taken calcium supplements (control group) by using propensity scores. The overall mean age was 59.9 ± 8.8 years and the percentage of women was 87.9% in our study population. Over a median follow-up of 54 months, the incidence rate of composite cardiovascular diseases (CVDs) per 1000 person-years was not different between the groups: 9.73 in the total calcium group and 8.97 in the control group [adjusted hazard ratio (HR): 1.12; 95% confidence interval (CI): 0.99-1.28; P = 0.08]. However, calcium supplementation without vitamin D was associated with an increased risk of composite CVD (HR: 1.54; 95% CI: 1.17-2.04; P < 0.01), especially non-fatal myocardial infarction (HR: 1.89; 95% CI: 1.23-2.91; P < 0.01), compared with no calcium supplementation.

CONCLUSION

Our population-based study supported that taking calcium supplementation combined with vitamin D did not appear to be harmful to cardiovascular health, but reminded that calcium supplementation without vitamin D should be used carefully even in populations with low dietary calcium intake.

Burden, trends, and risk factors for breast cancer in China from 1990 to 2019 and its predictions until 2034: an up-to-date overview and comparison with those in Japan and South Korea

BACKGROUND

The difference in epidemiological characteristics of breast cancer (BC) across countries is valuable for BC management and prevention. The study evaluated the up-to-date burden, trends, and risk factors of BC in China, Japan and South Korea during 1990-2019 and predicted the BC burden until 2034.

METHODS

Data on incident cases, deaths, disability-adjusted life-years (DALYs) and age-standardized rate (ASR) of BC were extracted from the Global Burden of Disease Study 2019. Trend analysis and prediction until 2034 were conducted by estimated annual percentage change and a Bayesian age-period-cohort model, respectively. Besides, the attributable burden to BC risk factors was also estimated.

RESULTS

In 2019, the number of BC incident cases, deaths and DALYs in China were 375,484, 96,306 and 2,957,453, respectively. The ASR of incidence increased, while that of death and DALYs decreased for Chinese females and Japanese and South Korean males during 1990-2019. High body-mass-index (BMI) was the largest contributor to Chinese female BC deaths and DALYs, while alcohol use was the greatest risk factor for Japanese and South Korean as well as Chinese males. The incident cases and deaths were expected to continue increase during 2020-2034 (except for Japanese female incident cases).

CONCLUSIONS

China had the greatest burden of BC among the three countries. Incident cases and deaths of BC were projected to increase over the next 15 years in China, particularly among Chinese males. Effective prevention and management strategies are urgently necessary for BC control in China.

Resolution of, and Risk of Incident Non-alcoholic Fatty Liver Disease With Changes in Serum 25-hydroxy Vitamin D Status

CONTEXT

A protective or causative role of vitamin D status on the risk of nonalcoholic fatty liver disease (NAFLD) remains inconclusive.

OBJECTIVE

To evaluate the association between changes in serum 25-hydroxyvitamin D [25(OH)D] status during follow-up and the risk of incident NAFLD and resolution of preexisting NAFLD.

DESIGN

A retrospective cohort study.

SETTING

Kangbuk Samsung Health Study based on routine health screening examinations.

PARTICIPANTS

Korean adults (mean age, 36.8 years; range, 18-96 years) who underwent comprehensive health examinations including assessment of serum 25(OH)D levels.

MAIN OUTCOME MEASURES

The main outcomes were (1) incidence and (2) resolution of NAFLD assessed by liver ultrasound. Cox proportional hazard models were used to estimate hazard ratios (HRs) with 95% CIs for outcomes according to serum 25(OH)D levels.

RESULTS

Among 139 599 participants without NAFLD at baseline, 27 531 developed NAFLD during follow-up. Serum 25(OH)D levels were significantly and inversely associated with NAFLD development. Among 48 702 participants with NAFLD at baseline, 13 449 showed NAFLD resolution. Multivariable-adjusted HR (95% CI) for NAFLD resolution comparing 25(OH)D 10 to <20, 20 to <30, and ≥30 ng/mL to <10 ng/mL were 1.09 (1.03-1.15), 1.13 (1.06-1.21), and 1.21 (1.09-1.35), respectively. Additionally, an increase in 25(OH)D levels between baseline and the subsequent visit (median, 1.8 years) was associated with decreased NAFLD incidence, while persistently adequate 25(OH)D levels over time was associated with decreased incidence and increased resolution of NAFLD.

CONCLUSIONS

Maintaining adequate serum 25(OH)D concentrations may be beneficial for both prevention as well as resolution of NAFLD.

Immunity-enhancing Micronutrients and Community Pharmacists: An Opportunity to Expand Self-Care Practices among the Public

Background: The urban lifestyle and environment pose a constant immune challenge to city dwellers. A major such challenge is influenza, which creates substantial public health and socio-economic burdens. The global healthcare paradigm has begun emphasizing the importance and cost-effectiveness of self-care in partnership with healthcare professionals such as community pharmacists for the management of mild ailments. For the general public, micronutrient supplementation is an affordable and potentially feasible self-care strategy for immunity enhancement and disease management. At the same time, micronutrient deficiencies are a serious public health concern in both developing and developed areas. Objective: This review focuses on the clinical evidence for the efficacy and safety of three key micronutrients — vitamins C, D and zinc — on respiratory infections. Key findings: These micronutrients are important for optimal immune function through their complementary roles in supporting both innate and adaptive immunity, as well as epithelial barriers. The need to improve public awareness of self-care in prevention and health management is highlighted by recent public health issues and the global fight against antimicrobial resistance. Community pharmacists could play a crucial role in empowering patient autonomy. Conclusion: With this review we aim to offer insights into the supplementation of these micronutrients as a self-care approach to the management of immune health.

Recent Information on Vitamin D Deficiency in an Adult Korean Population Visiting Local Clinics and Hospitals

We retrospectively reviewed serum 25-hydroxy vitamin D (25(OH)D) test results from an adult Korean population visiting local clinics and hospitals between July 2017 and December 2021 to gather recent information on the prevalence of vitamin D deficiency. The prevalence of vitamin D deficiency status was investigated according to criteria offered by various clinical guidelines. During the study period, 180,289 subjects (29,658 men and 150,631 women) were tested for 25(OH)D. The overall prevalence rates of vitamin D deficiency status based on 25(OH)D level were as follows: 0.4% for <5 ng/mL, 12.5% for <10 ng/mL, 20.6% for <12 ng/mL, 49.4% for <20 ng/mL, and <75.3% for <30 ng/mL. Women tested their 25(OH)D level more frequently than men, and the overall prevalence of 25(OH)D < 10 ng/mL was higher among women than men, while that of 25(OH)D <30 ng/mL was lower among women than men. Among age groups, the prevalence of 25(OH)D <30 ng/mL was higher in younger patients (20s−40s, 79.6−85.5%) than older ones (≥50 years, 62.6−69.2%). The overall prevalence of vitamin D deficiency decreased over time from 2018 to 2021. Future studies are needed to clarify the clinical impact of this change.

Low Vitamin D Status Is Associated with Increased Risk of Mortality in Korean Men and Adults with Hypertension: A Population-Based Cohort Study

Background Recent randomized controlled trials (RCTs) have shown no effect of vitamin D supplementation on cardiovascular disease, cancer events and mortality or all-cause mortality in Western populations. However, there has been a lack of research on populations with low vitamin D status, including Asians. In addition, there have been indications that an individual’s sex or hypertension status may affect the relationship between vitamin D status and mortality. In this study, we retrospectively assessed the association between vitamin D status and all-cause, cardiovascular, and cancer mortality in Koreans using a national database, and stratified participants according to sex and hypertension status. Methods Participants in the Korean Health and Nutrition Examination Survey 2008−2014, who consented to their data being synthesized with mortality data (up to December 2019), were included (n = 22,742; mean follow-up: 8.9 years). Participants’ level of serum 25-hydroxyvitamin D (25(OH)D) was measured by radioimmunoassay and categorized as <12, 12−19.9, and ≥20 ng/mL. A Cox proportional hazard model was used to assess the risk of mortality. Results In the total sample, risk of all-cause, cancer, and cardiovascular mortality was greater in adults with a serum 25(OH)D level below 12 and 12−19.9 ng/mL than those with ≥20 ng/mL. Men and adults with hypertension, who had low vitamin D status, had a higher risk of cancer and cardiovascular mortality, but not women or adults without hypertension. Similar results were observed when various cutoffs for 25(OH)D were employed, or extrinsic deaths were excluded. Conclusions Vitamin D status below 20 ng/mL is associated with a higher risk of mortality in Korean adults, especially in men and those with hypertension, on the basis of data from a nationally representative sample. Further RCTs on Asian adults with low vitamin D status are warranted.

Assessment of sunlight exposure across industries and occupations using blood vitamin D as a biomarker

Objective

Exposure to ultraviolet (UV) radiation from sunlight induces the production of essential vitamin D, whereas overexposure to sunlight leads to skin cancer. Sunlight exposure has been measured using questionnaires, dosimeters, and vitamin D levels. Several studies have measured vitamin D in the working population; however, these studies were limited to certain occupations such as farmers and construction workers. In the present study, we evaluated sunlight exposure using blood vitamin D as an exposure surrogate across industries and occupations.

Methods

The Korea National Health and Nutrition Examination Survey (KNHANES) is a nationwide study representing the Korean population. We analyzed data from KNHANES between 2008 and 2009. We examined the association between vitamin D levels and pertinent personal, seasonal, residential, and occupational factors. Furthermore, we developed a multiple regression model with factors other than occupational factors (industry and occupation) and obtained residual values. We computed the third quartile (Q3) of the residuals and then calculated the fractions exceeding the Q3 level for each combination of industry and occupation.

Results

Age, sex, body mass index, year, season, latitude, living area, living in an apartment, industry, and occupation were significantly associated with vitamin D levels. Based on the exceeding fraction, the armed forces showed the highest exceeding fraction level of 0.71.

Conclusions

Our results present the high exposure groups to sunlight across industries and occupations. Our results may provide a source for prioritizing occupational groups with a high risk of adverse health effects from sunlight exposure.

Perspectives on the systematic review for the 2020 Dietary Reference Intakes for Koreans for calcium

An accurate assessment of the recommended calcium (Ca) intake may contribute to reducing the risk of fractures and chronic diseases, ultimately improving quality of life. This review was performed to summarize key findings of Ca studies, investigate the effect of Ca intake on health outcomes, and determine the adequacy of evidence to revise the 2015 Dietary Reference Intakes for Koreans (KDRIs) for Ca in 2020. Databases were searched for intervention studies that assessed health outcomes by providing Ca in diets or as supplements. The framework of the systematic review comprised conducting literature searches, data extraction, quality assessment of the literature, and summarizing key findings relevant to set the Estimated Average Requirement (EAR) and Tolerable Upper Intake Level (UL) for Ca for the 2020 KDRI. The final search was performed in June 2019. A total of 13,309 studies were identified through databases and manual search. Sixtyfive studies were included in the final quality assessment and were summarized according to health indicators. As bone health was used as an indicator of the EAR for Ca, literature reports on bone health were further categorized by the life-cycle stage of the participants. This systematic review did not find new evidence that could be applied to the general Korean adult population, including postmenopausal women, for defining a new EAR for Ca in the 2020 KDRIs. Evidence in most of the reviewed literature was considered weak; however, some evidence was found that could improve the criteria on how the EAR for Ca was determined in children and adolescents. A review of the literature for the 2020 KDRIs for Ca did not find strong evidence in order to change the recommended values of the 2015 KDRIs. More clinical interventions are required among Koreans to strengthen the body of evidence to warrant the revision of the KDRIs.

Vitamin D Status and Bone Health in Postmenopausal Women Working in Greenhouses

Objectives

Greenhouse workers synthesize less vitamin D because ultraviolet light is blocked by the vinyl that covers the greenhouses. This study aimed to investigate the vitamin D status and bone health of postmenopausal women working in greenhouses.

Methods

This observational study enrolled women living in urban (n = 70, group 1) and rural areas (n = 91, group 2) and those working in greenhouses (n = 112, group 3). Serum levels of total and bioavailable 25-hydroxy-vitamin D [25(OH)D] and vitamin D binding protein were measured. T-scores of the lumbar spine and femur neck were measured by dual-energy X-ray absorptionetry.

Results

Heights were shorter in group 2 and group 3 than in group 1. Bioavailable 25(OH)D levels were higher and T-scores of the spine and femur were lower in both group 2 and 3 than in group 1. T-scores of the femur in group 3 were lower than those in group 2. The linear regression analysis showed that levels of bioavailable 25(OH)D significantly correlated with the spine T-scores but not with the femur T-scores. The prevalence of spinal osteoporosis was higher in both groups 2 and 3 compared to group 1. Group 3 demonstrated greater femur osteoporosis compared to groups 1 and 2.

Conclusions

Vitamin D plays an important role in spinal bone health. Moreover, working conditions are likely to play an important role in femur bone health. Therefore, appropriate working conditions and nutrition are paramount to improve bone health in postmenopausal women working in greenhouses.

Gender difference in the relationship between anemia and vitamin D in Korean adults: the fifth Korea National Health and Nutrition Examination Survey

This study was conducted to assess the relationship between vitamin D deficiency and anemia, by gender, in Korean adults. The data of 16,060 adults were analyzed (men, 6,840; premenopausal women, 4,916; postmenopausal women, 4,340) from the fifth Korean National Health and Nutrition Examination Survey (KNHANES V) (2010–2012). There were several key findings. First, after adjusting for related variables, the odds ratio (OR) of anemia [hemoglobin (Hb) <13 g/dl in men or Hb <12 g/dl in women] using the vitamin D normal group {25-hydroxyvitamin [25(OH)D] ≥15.0 ng/ml} as reference, was significant for the vitamin D deficient group [25(OH)D <15.0 ng/ml] in the overall population [OR, 1.310; 95% confidence interval (CI), 1.168–1.470]. Second, the OR of anemia, using the vitamin D normal group as reference, was significant for the vitamin D deficient group in premenopausal women (OR, 1.293; 95% CI, 1.105–1.513). However, vitamin D deficiency in the vitamin D normal group in men (OR, 1.093; 95% CI, 0.806–1.484) and postmenopausal women (OR, 1.130; 95% CI, 0.906–1.409) was not significant. In conclusion, Vitamin D deficiency is positively associated with anemia in premenopausal women, but not in men and postmenopausal women.

Trends in Vitamin D Status Around the World

Vitamin D status varies across all continents and countries. Vitamin D status usually is adequate in Latin America and Australia, but in contrast it is very low in the Middle East and some countries in Asia. Trends in vitamin D status, whether it improves or declines over the years, carry important messages. Trends usually are small, but can be predictors and indicators of general health. Vitamin D status has improved in the older population in the United States, and improvement relates to dairy use and vitamin D supplements. To the contrary, vitamin D status has declined in the Inuit population of Canada due to a change from a traditional fish diet to a Western diet. A large improvement was seen in Finland after mandatory fortification of dairy products was introduced. Determinants of decline are less sun exposure, increased use of sunscreen, increase of body mass index (BMI), less physical activity, and poor socioeconomic status. Determinants of increase are food fortification with vitamin D and vitamin D supplements. Food fortification can lead to a population-wide increase in vitamin D status as shown by the Finnish example. © 2021 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Differences in Fat-Free Mass According to Serum Vitamin D Level and Calcium Intake: Korea National Health and Nutrition Examination Survey 2008-2011

We analyzed the differences in fat-free mass (FFM) according to serum vitamin D level (VitD) and daily calcium intake (Ca) in 14,444 adults aged over 19 years. We used data from the 4th and 5th Korea National Health and Nutrition Examination Surveys (2008–2011). FFM was measured using dual-energy X-ray absorptiometry. VitD was classified as insufficient or sufficient (cutoff: 20 ng/mL). Ca was classified as unsatisfactory or satisfactory (recommended daily intake: 700 mg). In men, the FFM of group 2 (VitD ≥ 20 ng/mL; Ca < 700 mg), group 3 (VitD < 20 ng/mL; Ca ≥ 700 mg) and group 4 (VitD ≥ 20 ng/mL; Ca ≥ 700 mg) was 0.50 kg (95% confidence interval (CI), 0.084–0.92), 0.78 kg (95% CI, 0.26–1.29) and 1.58 kg (95% CI, 0.95–2.21) higher than that of group 1 (VitD < 20 ng/mL; Ca < 700 mg), respectively. In women, a 1 ng/mL increase in VitD was associated with a 0.023 kg increase in FFM (95% CI, 0.003–0.043) and a 1 g increase in Ca was associated with a 0.62 kg increase in FFM (95% CI, 0.067–1.16). High VitD and Ca were associated with a high FFM.

Dietary intake and nutritional status of Korean children and adolescents: a review of national survey data

In Korea, several national cross-sectional surveys monitor the diet, nutritional status, and health status of children. This continual dedicated national surveillance system contributes to the identification of nutritional and health issues, establishment of public health policies, and development of nutrition recommendations. This paper provides recent information about the Korea National Health and Nutrition Examination Survey and the Korean Youth Risk Behavior Web-based Survey and describes key nationwide survey findings published in the last 5 years on infant feeding practices and the dietary intake and nutritional status of Korean infants, children, and adolescents. There have been increasing trends in children, and teenagers who skip breakfast, eat fast food, consume sugary drinks, have vitamin D deficiency, and are obese. This review will inform pediatricians, nutritionists, and other health care practitioners who track children's growth and development. It may also help researchers and policymakers identify diet-related policies and strategies for chronic disease prevention in Korean infants, children, and adolescents.

Inverse Association between Serum 25-hydroxyvitamin D Levels and Risk of Suspected Non-Alcoholic Fatty Liver Disease in Obese Population

BACKGROUND

Worldwide, vitamin D deficiency is a public health issue and the prevalence of obesity and non-alcoholic fatty liver disease (NAFLD) are rapidly increasing. There are a limited number of studies assessing the association between serum levels of 25-hydroxyvitamin D (25(OH)D) and NAFLD risk in obese population.

OBJECTIVE

We evaluated the associations between serum 25(OH)D levels and risk of suspected NAFLD after stratification by obesity using data from the Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2014.

METHODS

This study included 25,755 subjects without significant alcohol consumption for the serum alanine aminotransferase (ALT) and hepatic steatosis index (HSI) analyses (8922 subjects for the serum gamma-glutamyl transferase (GGT) and fatty liver index (FLI) analyses), based on a cross-sectional study design. Serum 25(OH)D levels were measured using a Gamma counter with radioimmunoassay. A survey logistic regression model was applied to estimate ORs and 95% CIs. Restricted cubic smoothing splines were applied to evaluate nonlinear associations.

RESULTS

The risk of suspected NAFLD was reduced per unit of natural log-transformed serum 25(OH)D concentration in obese individuals (OR [95% (CI)]; for ALT, 0.80 [0.67, 0.96]; for GGT, 0.70 [0.49, 0.99; for FLI, 0.68 [0.47, 1.01]; for HSI, 0.70 [0.56, 0.87]). The ORs [95% CI] of suspected NAFLD changed across the quartiles: for serum ALT, from 1.02 [0.85, 1.23] to 0.72 [0.59, 0.87]; for serum GGT, from 0.79 [0.56, 1.13] to 0.64 [0.44, 0.92]; for FLI, from 0.98 [0.67, 1.44] to 0.70 [0.48, 1.02]; and for HSI, from 0.91 [0.73, 1.14] to 0.65 [0.52, 0.81] with dose-response relationships (all p for trend < 0.01).

CONCLUSIONS

This study suggests that vitamin D sufficiency for public health should be emphasized in order to prevent adverse health effects in obese populations.

History of anemia and long-term mortality due to infection: a cohort study with 12 years follow-up in South Korea

BACKGROUND

Anemia, which is a condition with reduced healthy red blood cells, is reported to be closely related to the development of infectious diseases. We aimed to investigate the association between history of anemia and 12-year mortality rate due to infections, and compare it with that among non-anemic individuals.

METHODS

Data from the National Health Insurance Service Health Screening Cohort were used in this population-based cohort study. Adults who underwent standardized medical examination between and 2002-2003 were included, and the mortality rate due to infection between 2004 and 2015 was analyzed. Individuals were considered to have a history of anemia if the serum hemoglobin level in 2002-2003 was < 12 g/dL for women and < 13 g/dL for men. The severity of anemia at that time was categorized as mild (12 g/dL > hemoglobin ≥11 g/dL in women and 13 g/dL > hemoglobin ≥11 g/dL in men), moderate (hemoglobin 8-10.9 g/dL), or severe (hemoglobin < 8 g/dL). Propensity score (PS) matching and Cox regression analysis were used as statistical methods.

RESULTS

Overall, 512,905 individuals were included in this study. The mean age of the participants was 54.5 years old (range: 40-98), and 49,042 (9.6%) individuals were classified in the anemic group, which comprised of 36,383 (7.1%), 11,787 (2.3%), and 872 (0.2%) participants in the mild, moderate, and severe sub-groups, respectively. After PS matching, 49,039 individuals in each group were included in the analysis. The risk of mortality due to infection in the anemic group was 1.77-fold higher (hazard ratio [HR]: 1.77, 95% confidence interval [CI]: 1.52-2.60; P < 0.001) than that in the non-anemic group. In the subgroup analysis, the mild and moderate anemia groups had 1.38-fold (HR: 1.38, 95% CI: 1.23 to 1.55; P < 0.001) and 2.02-fold (HR: 2.02, 95% CI: 1.62 to 2.50; P < 0.001) risk of mortality due to infection compared to that of the non-anemic group, respectively. The severe anemia group did not have a significantly different risk of mortality due to infection (P = 0.448).

CONCLUSIONS

History of anemia was associated with increased mortality rate due to infection at 12-year follow-up.

Clinical significance of vitamin D in idiopathic normal pressure hydrocephalus

BACKGROUND

Although recent studies show vitamin D deficiency is associated with cognitive decline, urinary incontinence, and gait instability, there has been no study on the effect of vitamin D on idiopathic normal pressure hydrocephalus (iNPH) characterized by the classic symptom triad of cognitive decline, urinary incontinence, and gait instability. We investigated the clinical significance of vitamin D in patients with iNPH.

METHODS

Between 2017 and 2020, 44 patients who underwent ventriculoperitoneal shunt surgery were divided into low (< 15 ng/mL) and high (≥ 15 ng/mL) vitamin D groups according to the concentration of 25(OH)D, an effective indicator of vitamin D status. They were respectively evaluated according to clinical and radiological findings.

RESULTS

The low vitamin D group (n = 24) showed lower preoperative cognition compared to the high vitamin D group (n = 20) in terms of Korean-Mini Mental Status Examination (K-MMSE) and iNPH grading scale (iNPHGS) (K-MMSE: 20.5 ± 5.4 versus 24.0 ± 4.5, p = 0.041; iNPHGS cognitive score: 2 ± 0.9 versus 1 ± 0.6, p = 0.025). And the low vitamin D group showed pre- and postoperatively more severe urinary incontinence (preoperative iNPHGS urinary score: 1 ± 1.0 versus 0 ± 0.9, p = 0.012; postoperative iNPHGS urinary score:1 ± 1.0 versus 0 ± 0.9, p = 0.014). The score of narrow high-convexity sulci for the low vitamin D group was lower (low vitamin D group: 1 ± 0.7 versus high vitamin D group: 2 ± 0.4, p = 0.031).

CONCLUSION

Lower concentration of vitamin D in iNPH may be related to lower preoperative cognition, pre- and postoperative urinary incontinence, and brain morphological change.

Association of serum 25(OH)Vit-D levels with risk of pediatric fractures: a systematic review and meta-analysis

The association between the risk of fractures and suboptimal vitamin D (Vit-D) status remains controversial in children. This meta-analysis suggested that serum 25(OH)Vit-D levels were lower in pediatric cases with fractures. 25-hydroxyvitamin D (25(OH)Vit-D) levels less than 50 nmol/L were associated with increased fracture risk in children.

INTRODUCTION

This study aimed to assess the association between serum 25(OH)Vit-D and the risk of fractures in children, and to explore the sources of heterogeneity and investigate their impact on results.

METHODS

Systematic review and meta-analysis were conducted for observational studies comparing serum 25(OH)Vit-D levels between fracture and non-fracture pediatric cases. The quality of the included studies was assessed using the Newcastle-Ottawa Scale (NOS).

RESULTS

Analysis on 17 case-control and 6 cross-sectional studies (2929 fracture cases and 5000 controls) suggested that 25(OH)Vit-D was lower in fracture cases than in controls (pooled mean difference (MD) = - 3.51 nmol/L; 95% confidence interval (CI): - 5.60 to - 1.42) with a heterogeneity (I²) of 73.9%. The sensitivity analysis which merged the case-control studies that had a NOS score ≥ 4 showed a pooled MD of - 4.35 nmol/L (95% CI: - 6.64 to - 2.06) with a heterogeneity (I²) of 35.9%. Pooled odds ratio of fracture in subjects with 25(OH)Vit-D ≤ 50 nmol/L compared to subjects with 25(OH)Vit-D > 50 nmol/L was 1.29 (95% CI: 1.10 to 1.53; I² < 1%).

CONCLUSION

This study indicated that serum 25(OH)Vit-D levels were lower in pediatric patients with fractures. 25(OH)Vit-D ≤ 50 nmol/L was associated with increased fracture risk in children.

A high prevalence of prediabetes and vitamin D deficiency are more closely associated in women: results of a cross-sectional study

OBJECTIVE

Many studies have shown that vitamin D deficiency is associated with insulin resistance and metabolic syndrome. However, few studies have shown independent associations between vitamin D deficiency and the metabolic characteristics of prediabetes. We aimed to evaluate the relationship between serum vitamin D concentration and metabolic risk factors in adults with prediabetes.

METHODS

We enrolled 161 patients aged 25 to 75 years in a cross-sectional study and collected clinical and biochemical data, including 25-hydroxyvitamin D (25[OH]D) status and fasting glucose concentration. Vitamin D status was defined as follows: deficiency (25[OH]D <49.9 ng/mL), insufficiency (49.9 to 74.9 nmol/L) or sufficiency (>74.9 nmol/L). Prediabetes was defined using fasting plasma glucose concentrations of 5.55 to 6.49 mmol/L.

RESULTS

The prevalences of vitamin D deficiency and insufficiency were 49.7% and 24.8%, respectively. Participants with vitamin D deficiency had a higher prevalence of prediabetes than those without (53.8% vs. 32.1%), and there was a significant relationship between female sex and vitamin D status (odds ratio: 1.382; 95% confidence interval: 0.335-5.693).

CONCLUSION

Vitamin D deficiency is more closely associated with a high prevalence of prediabetes in women than in men. Further studies are needed to elucidate the explanation for this association.