• Nutrition Research and Practice
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• v.13 no.6
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• pp.498-508
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• 2019

BACKGROUND/OBJECTIVES: Lower circulating 25-hydroxyvitamin D [25(OH)D] levels are associated with a higher risk of hypertension (HTN); however, it remains unclear whether the relationship is causal. We aimed to evaluate the causal effects of circulating 25(OH)D levels on the prevalence of HTN in the Korean population using the Mendelian randomization (MR) approach. SUBJECTS/METHODS: Epidemiological data, serum 25(OH)D data, and genomic DNA biospecimens were obtained from 2,591 participants, a subset of the study population in the Korea National Health and Nutrition Survey 2011-2012. Five 25(OH)D-related single nucleotide polymorphisms (SNPs; DHCR7 rs12785878, CYP2R1 rs10741657, CYP2R1 rs12794714, CYP24A1 rs6013897, and GC rs2282679), identified a priori from genome-wide association studies, were used as instrument variables (IVs) for serum 25(OH)D levels. In the MR analysis, we performed IV analyses using the two-stage least squares method. RESULTS: In the observational analysis, circulating 25(OH)D levels were found to be inversely associated with the HTN prevalence in ordinary least squares models (odds ratio: 0.97, 95% confidence interval: 0.96, 0.99) after adjusting for the potential confounders. There were differences in the circulating 25(OH)D levels across genotypes of individual SNPs. In the MR analysis, using individual SNPs as IVs, 25(OH)D levels were not associated with the HTN prevalence. CONCLUSIONS: We found no association between genetically determined circulating 25(OH)D levels and HTN in Korean adults. Our results are listed owing to the relatively small sample size and possible weak instrument bias; therefore, further studies are needed to confirm these results.

• Osteoporosis and Sarcopenia
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• v.2 no.4
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• pp.228-237
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• 2016

Objective: There has been no prospective study that examined intramuscular injection of high-dose vitamin D in Korean adults. The aim of this study was to assess the efficacy and safety of high-dose vitamin $D_3$ after intramuscular injection in Korean adults with vitamin D deficiency. Method: This study was a 24-week, prospective, multicenter, randomized, double-blind, placebo-controlled trial. A total of 84 subjects ${\geq}19$ and <65 years of age were randomly allocated to either the vitamin $D_3$ or placebo group in a 2:1 ratio. After randomization, a single injection of plain vitamin $D_3$ 200,000 IU or placebo was intramuscularly administered. If serum 25-hydroxyvitamin D (25[OH]D) concentrations were <30 ng/mLon week 12 or thereafter, a repeat injection was administered. Results: After a single intramuscular injection of vitamin $D_3$ to adults with vitamin D deficiency, the proportion of subjects with serum 25(OH)D concentrations ${\geq}30ng/mL$ within 12 weeks was 46.4% in the vitamin $D_3$ group and 3.6% in the placebo group (p<0.0001). The proportion of subjects with serum 25(OH)D concentrations ${\geq}30ng/mL$ within 24 weeks was 73.2% in the vitamin $D_3$ group and 3.6% in the placebo group (p<0.0001). Mean change in serum 25(OH)D concentrations at weeks 12 and 24 after vitamin $D_3$ injection was $12.8{\pm}8.1$ and $21.5{\pm}8.1ng/mL$, respectively, in the vitamin $D_3$ group, with no significant changes in the placebo group. Serum parathyroid hormone concentrations showed a significant decrease in the vitamin $D_3$ group but no change in the placebo group. Conclusion: Intramuscular injection of vitamin $D_3$ 200,000 IU was superior to placebo in terms of its impact on serum 25(OH)D concentrations, and is considered to be safe and effective in Korean adults with vitamin D deficiency.

• Journal of Periodontal and Implant Science
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• v.50 no.6
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• pp.368-378
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• 2020

Purpose: Vitamin D deficiency may cause bone loss and increased inflammation, which are well-known symptoms of periodontal disease. This study investigated whether serum 25-hydroxyvitamin D (25(OH)D) levels are associated with periodontal disease status and tooth loss. Methods: Cross-sectional data from 5,405 individuals aged ≥50 years (2,253 males and 3,152 females) were obtained from the 2008-2010 Dong-gu study, a prospective cohort study of risk factors for chronic diseases. Periodontal examinations were conducted to evaluate the number of remaining teeth, the periodontal probing depth (PPD), the clinical attachment level (CAL), and bleeding on probing. The percentages of sites with PPD ≥4 mm and CAL ≥4 mm were recorded for each participant. The severity of periodontitis was classified using the Centers for Disease Control and Prevention and the American Academy of Periodontology case definitions. Serum 25(OH)D levels were classified as reflecting severe deficiency, deficiency, insufficiency, or sufficiency. Multivariate linear regression analysis was performed to assess the associations of serum 25(OH)D levels with periodontal parameters and the number of remaining teeth after adjusting for confounders including age, smoking status, alcohol consumption status, month of blood collection, and physical activity. Multivariate logistic regression was used to evaluate the association between serum vitamin D levels and severe periodontitis. An overall statistical analysis and a stratified analysis by sex were performed. Results: Overall, the rates of severe deficiency, deficiency, insufficiency, and sufficiency were 6.5%, 67.9%, 22.4%, and 3.2%, respectively. After adjustment for confounders, vitamin D levels were directly associated with the number of remaining teeth, an association that was significant in males, but not in females. Sufficient serum 25(OH)D was associated with a low frequency of severe periodontitis. Conclusions: This population-based cross-sectional study indicates that low serum 25(OH) D is significantly associated with tooth loss and severe periodontitis in Koreans aged 50 years and older.

• Nutrition Research and Practice
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• v.10 no.2
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• pp.206-211
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• 2016

BACKGROUND/OBJECTIVES: Obesity, which is a known risk factor for many chronic diseases, has also been associated with vitamin D deficiency. This study explored the relationship between serum 25-hydroxy-vitamin D [25(OH)D] concentrations and adiposity measures in a general Korean population using the most recent, nationally representative survey data. SUBJECTS/METHODS: The study sample consisted of 4,771 Korean adults (${\geq}19years$) who participated in the fifth Korean National Health and Nutrition Examination Surveys. Serum 25(OH)D was determined by radioimmunoassay. Body mass index (BMI), waist circumference (WC) and total body fat content were measured as adiposity measurements. Total body fat content was measured by dual-energy X-ray absorptiometry. RESULTS: The serum 25(OH)D level was significantly higher in men than in women. Serum 25(OH)D concentration was positively correlated with energy intake, and it was negatively correlated with total body fat content (P < 0.0001) and percentage body fat (P < 0.0001) after adjustment for age in both sexes, while was inversely correlated with BMI only in women. In multivariable regression analysis, serum 25(OH)D was inversely associated with the total body fat content after adjustment for age, BMI, education, region, smoking, alcohol consumption, physical activity, and energy intake only in men (P = 0.0047). However, the serum 25(OH)D concentration was not associated with WC or BMI, indicators of adiposity after adjustment for potential risk factors. CONCLUSIONS: Serum 25(OH)D concentration was independently associated with the total body fat content in a general Korean population, but it may be not associated with the indicators for estimating adiposity, such as WC or BMI.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.14
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• pp.5983-5986
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• 2015

Background: Serum 25-hydroxyvitamin D insufficiency is very common in Pakistan and is often related to inferior prognosis in some cancers but limited data exist for hematopoietic malignancies. This study was conducted to determine the vitamin D insufficiency in B-chronic lymphoid leukemia (CLL) cases at the time of presentation and its possible correlation with clinical staging, hematological parameters and biochemical markers. Materials and Methods: This descriptive cross sectional study was carried at Liaquat National Hospital from January 2011 to June 2013. Sixty patients with B-chronic lymphoid leukemia were enrolled. Complete blood count, vitamin D levels, serum urea, creatinine, uric acid and LDH levels were assessed. Data were compiled and analyzed using SPSS version 21. Results: Out of 60 patients, 42 (70%) were male and 18 (30%) were female. Mean age was $59.0{\pm}9.2years$. The frequency of vitamin D insufficiency was found to be 56.7%. Overall insufficiency was more frequently seen in male gender (40%). Vitamin D insufficiency demonstrated a positive association with low lactate dehydrogenase levels (P=0.005). No links were established with age, clinical stage, hematological and other biochemical markers. Conclusions: Vitamin D insufficiency is high compared with Western studies. Whether normalization of vitamin D insufficiency in deficient B-CLL patients could improve the clinical outcome or delay disease progression will require further studies.

• Asian Pacific Journal of Cancer Prevention
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• v.16 no.6
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• pp.2227-2230
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• 2015

Background: Prostate cancer (PCa) is one of the most commonly diagnosed neoplasms and the second leading cause of cancer death in men in the Western world. Vitamin D (1,25dihydroxy vitamin D) is linked to many biological processes that influence oncogenesis but data on relations between its genetic variants and cancer risk have been inconsistent. The aim of this study was to determine associations between a vitamin D genetic polymorphism and 25-hydroxyvitamin D [25(OH)D] levels and prostate cancer. Materials and Methods: Genomic DNA was extracted from 124 Jordanian prostate cancer patients and 100 healthy volunteers. Ethical approval was granted from the ethical committee at Hashemite University and written consent was given by all patients. PCR was used to amplify the vitamin D receptor Fok1 polymorphism fragment. 25(OH)D serum levels were measured by competitive immunoassay. Results: All genotypes were in Hardy-Weinberg equilibrium. Genotype frequency for Fok1 genotypes FF, Ff and ff was 30.7%, 61.3% and 8.06%, for prostate cancer patients, while frequencies for the control group was 28.0%, 66.0% and 6.0%, respectively, with no significant differences. Vitamin D serum level was significantly lower in prostate cancer patients (mean 7.7 ng/ml) compared to the control group (21.8 ng/ml). No significant association was noted between 25(OH)D and VDR Fok1 gene polymorphism among Jordanians overall, but significant associations were evident among prostate cancer patients (FF, Ff and ff : 25(OH)D levels of 6.2, 8.2 and 9.9) and controls (19.0, 22.5 and 26.3, respectively). An inverse association was noted between 25(OH)D serum level less than 10ng/ml and prostate cancer risk (OR 35.5 and 95% CI 14.3- 88.0). Conclusions: There is strong inverse association between 25(OH)D serum level less than 10ng/ml level and prostate cancer risk.

• Clinical and Experimental Pediatrics
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• v.54 no.2
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• pp.51-54
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• 2011

Vitamin D is present in two forms, ergocalciferol (vitamin $D_2$) produced by plants and cholecalciferol (vitamin $D_3$) produced by animal tissues or by the action of ultraviolet light on 7-dehydrocholesterol in human skin. Both forms of vitamin D are biologically inactive pro-hormones that must undergo sequential hydroxylations in the liver and the kidney before they can bind to and activate the vitamin D receptor. The hormonally active form of vitamin D, 1,25-dihydroxyvitamin D3 $[1,25(OH)_2D]$, plays an essential role in calcium and phosphate metabolism, bone growth, and cellular differentiation. Renal synthesis of $1,25(OH)_2D$ from its endogenous precursor, 25-hydroxyvitamin D (25OHD), is the rate-limiting and is catalyzed by the $1{\alpha}$-hydroxylase. Vitamin D dependent rickets type I (VDDR-I), also referred to as vitamin D $1{\alpha}$-hydroxylase deficiency or pseudovitamin D deficiency rickets, is an autosomal recessive disorder characterized clinically by hypotonia, muscle weakness, growth failure, hypocalcemic seizures in early infancy, and radiographic findings of rickets. Characteristic laboratory features are hypocalcemia, increased serum concentrations of parathyroid hormone (PTH), and low or undetectable serum concentrations of $1,25(OH)_2D$ despite normal or increased concentrations of 25OHD. Recent advances have showed in the cloning of the human $1{\alpha}$-hydroxylase and revealed mutations in its gene that cause VDDR-I. This review presents the biology of vitamin D, and $1{\alpha}$-hydroxylase mutations with clinical findings.

• Nutrition Research and Practice
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• v.6 no.2
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• pp.162-168
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• 2012

Vitamin D deficiency is a risk factor for metabolic syndromes. We examined whether vitamin D deficiency altered the prevalence of cardiovascular disease (CVD) in older Koreans. Cross-sectional analysis of data from the Korean National Health and Nutrition Examination Survey IV 2008-2009 was used to examine the association between serum 25-hydroxyvitamin D (25(OH)D) levels and the prevalence of CVD in a representative population-based sample of 5,559 men and women aged ${\geq}50$ years. CVD was defined as angina pectoris, myocardial infarction, or stroke. The prevalence of CVD (7.0%) in the older Korean population was lower than that in the older US population, although average serum 25(OH)D levels were much lower in the Korean population. Additionally, serum 25(OH)D levels did not differ significantly between the CVD and non-CVD groups. However, subjects in the lowest category (< 25 nmol/l) of serum 25(OH)D level had the greatest prevalence of CVD, about two-fold higher than subjects in the highest category (> 75 nmol/l), after adjusting for age, gender, body mass index, education level, residence location, and region. The prevalence of other risk factors for CVD, including higher waist circumference, fasting glucose, low-density lipoprotein (LDL) cholesterol, and triglyceride levels and lower high-density lipoprotein (HDL) cholesterol levels, was also higher among subjects in the lowest category than among those in the highest category. In conclusion, low serum 25(OH)D may be an independent risk factor for CVD in older Koreans.

• Journal of Nutrition and Health
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• v.49 no.6
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• pp.437-446
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• 2016

Purpose: The purpose of this study was to estimate dietary intake of vitamin D and the relationship between serum 25-hydroxyvitamin D (25OHD) concentration and bone mineral density (BMD) in Korean adults using the 2011 data from the Korea National Health and Nutrition Examination Survey. Methods: Daily intake of vitamin D and ratio of subjects that consumed less vitamin D than adequate intake (AI) were estimated in 4,879 Korean adults. The relationship between daily intake of vitamin D and serum 25OHD and BMD were analyzed. Results: Average daily intakes of vitamin D were $3.84{\pm}0.23{\mu}g/day$ for men and $2.22{\pm}0.11{\mu}g/day$ for women. Approximately 72~97% of men and 80~99% of women consumed less than the AI of vitamin D for Koreans. Serum 25OHD concentration increased with age, and the ratios of serum vitamin D deficiency (< 20 ng/mL) were 47.8~81.1% for men and 59.4~92.8% for women. Average intake of vitamin D was higher in subjects aged < 50 yr than in those ${\geq}50yr$, but lower in serum 25OHD concentration. In subjects aged < 50 yr, serum 25OHD was higher in subjects that consumed $10{\mu}g/day$ of vitamin D than in those that consumed less than $5{\mu}g/day$. In female subjects aged ${\geq}50yr$, average intake of vitamin D was associated with higher bone mineral density. Conclusion: It was found that dietary intake of vitamin D could increase serum 25OHD concentration in young adults and bone mineral density in old women. Therefore, nutrition policies for enriched foods with vitamin D and nutrition education to consume more vitamin D-rich foods are needed to ameliorate vitamin D status of the Korean population. Adequate intake for Korean population aged < 50 yr might be adjusted upwardly up to $10{\mu}g/day$.

• Clinical and Experimental Pediatrics
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• v.56 no.5
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• pp.205-210
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• 2013

Purpose: The aim of this study was to recognize the state of vitamin D among healthy infants aged 1 to 6 months in South Korea, and also to identify the risk factors affecting the level of vitamin D. Methods: A total of 117 infants were enrolled in this study for 12 months, from March 1, 2011 to February 29, 2012. Serum levels of 25-hydroxyvitamin D (25[OH]D), calcium, phosphorus, and alkaline phosphatase were measured and data including birth weight, body weight, sex, feeding pattern, delivery mode, siblings and maternal age and occupation were collected. Data was mainly analyzed with independent t-test model. Results: We determined that the prevalence of vitamin D deficiency (serum 25[OH]D<20 ng/mL [50 mmol/L]) was 48.7% in the population investigated. Particularly in breastfed infants, the prevalence of vitamin D deficiency was strikingly high (90.4%). The mean serum level of 25(OH)D in breastfed infants was lower than that of formula fed infants (9.35 ng/mL vs. 28.79 ng/mL). Also female infants showed lower mean serum level of 25(OH)D than male. Mean serum values of calcium and phosphorus had positive correlation with vitamin D state (P<0.001). Conclusion: Vitamin D deficiency was found to be very common in infants aged 1 to 6 months in South Korea, and breast feeding was the most critical risk factor of vitamin D deficiency. Therefore we suggest to start vitamin D supplementation in South Korea, as soon as possible, to all infants, including breastfed and female infants.