• Journal of Nutrition and Health
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• v.39 no.7
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• pp.649-660
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• 2006

This study was performed to estimate serum 2S-hydroxyvitamin D (25-OHD) level in wintertime and to evaluate the relationship between serum 25-OHD level and associated factors in 50 premenopausal working women aged 30-49 y in Busan. The serum 25-OHD level was measured by radioimmunoassay. Data for physiological characteristics, lifestyle factors, physical activity and nutrient intake was assessed by questionnaire including information about outdoor activity time, daily activity diary and 24hr recall method. The mean vitamin D intake was $4.24{\mu}g$, which corresponded to 84.9% of the Korean RDA. The mean level of serum 25-OHD was 25.7 ng/mL. Vitamin D deficiency (25-OHD < 7nmol/L) and toxicity $(25-OHD{\geq}75\;nmol/L)$ were not found in the subjects. However, the prevalence of vitamin D insufficiency (25-OHD < 15 nmol/L) and hypovitaminosis D (25-OHD < 30 nmol/L) were 12% and 60% respectively. The serum 25-OHD level showed positive significant correlations with the duration of outdoor activity per weekdays (p < 0.05). Our findings suggest that hypovitaminosis D was common in the subjects in wintertime. So nutritional education for increasing outdoor activities is needed for premenopausal working women to increase vitamin D status in wintertime.

• Nutritional Sciences
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• v.8 no.2
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• pp.111-117
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• 2005

It has been more than three decades since the first assay assessing circulating 25 (OH)D in human subjects was performed That publication as well as several that followed it defined 'normal' nutritional vitamin D status in human populations. Recently, the wisdom by which 'normal' circulating 25 (OH)D levels in human subjects were assigned in the past has come under question. It appears that sampling human subjects, who appear to be free from disease, and assessing 'normal' circulating 25 (OH)D levels by plotting a Gaussian distribution is grossly inaccurate. There are many reasons why this method is inaccurate, including race, lifestyle habits, sunscreen usage, age, latitude, and inappropriately low dietary recommendations for vitamin D. For instance, a 400 IU/day. AI for vitamin D is insignificant when one considers that a 10-15 minute whole body exposure to peak summer sun will generate and release up to 20,000 IU vitamin $D_3$ into the circulation. Recent studies, which orally administered up to 10,000 IU/day vitamin $D_3$ to human subjects for several months, have successfully elevated circulating 25 (OH)D levels to those observed in individuals from sun-rich environments. Further, we are now able to accurately assess sufficient circulating 25 (OH)D levels utilizing specific biomarkers instead of guessing what an adequate level is. These biomarkers include intact parathyroid hormone (PTH), calcium absorption, bone mineral density (BMD), insulin resistance and pancreatic beta cell function. Using the data from these biomarkers, vitamin D deficiency should be defined as circulating levels of 25 (OH)D$\leq$30 ng/mL. In certain cases, such as pregnancy and lactation, significantly higher circulating 25 (OH)D levels would almost certainly be beneficial to both the mother and recipient fetus/infant.

• Proceedings of the Korean Nutrition Society Conference
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• 2004.11a
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• pp.22-33
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• 2004

It has been more than three decades since the first assay assessing circulating 25(OH)D in human subjects was performed. That publication as well as several that followed it defined 'normal' nutritional vitamin D status in human populations. Recently, the wisdom by which 'normal' circulating 25(OH)D levels in human subjects were assigned in the past has come under question. It appears that sampling human subjects, who appear to be free from disease, and assessing 'normal' circulating 25(OH)D levels by plotting a Gaussian distribution is grossly inaccurate. There are many reasons why this method is inaccurate, including race, lifestyle habits, sunscreen usage, age, latitude, and inappropriately low dietary recommendations for vitamin D. For instance, a 400IU/day. AI for vitamin D is insignificant when one considers that a 10-15 minute whole body exposure to peak summer sun will generate and release up to 20,000 IU vitamin $D_3$ into the circulation. Recent studies, which orally administered up to 10,000 IU/day vitamin $D_3$ to human subjects for several months, have successfully elevated circulating 25(OH)D levels to those observed in individuals from sun-rich environments. Further, we are now able to accurately assess sufficient circulating 25(OH)D levels utilizing specific biomarkers instead of guessing what an adequate level is. These biomarkers include intact parathyroid hormone (PTH), calcium absorption, bone mineral density (BMD), insulin resistance and pancreatic beta cell function. Using the data from these biomarkers, vitamin D deficiency should be defined as circulating levels of $25(OH)D{\leq}30ng/mL$. In certain cases, such as pregnancy and lactation, significantly higher circulating 25(OH)D levels would almost certainly be beneficial to both the mother and recipient fetus/infant.

• Journal of The Korean Society of Integrative Medicine
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• v.7 no.4
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• pp.71-79
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• 2019

Purpose : Several studies suggest that smoking and vitamin D level is a risk factor of metabolic syndrome. The objective of this study is to evaluate the association between smoking status, vitamin D levels and the Korean adult male and female metabolic syndrome. Methods : We assessed 3796 participants aged 19 years and older from the Korean National Health and Nutritional Examination Survey 2013, 2014. Smoking statuses were collected from self-reported questionnaires. Subjects were divided into three categories: non-smokers, former smokers, and current smokers. Vitamin D was tested by Radioimmunoassay method and the value of serum 25-hydroxyvitamin D, which is an index of vitamin D status in the body, was used. The diagnosis of metabolic syndrome was made using criteria modified NCEP-ATP III. Logistic regression analysis was used to calculate odds ratios between smoking status, vitamin D levels, and metabolic syndrome. Results : The overall prevalence of metabolic syndrome was 23.0 % in men and 15.4 % in women. After adjusting for smoking, the odds ratio for men's metabolic syndrome in current smokers was 1.77 (95 % CI, 1.30~2.41), while for former smokers OR was 1.63 (95 % CI, 1.15~2.31) compared with nonsmokers. After adjustment vitamin D, the odds ratio for women's metabolic syndrome in vitamin D deficiency was 1.44 (95 % CI, 1.11~1.87) compared with normal. Conclusion : Smoking status was associated with an increased risk of metabolic syndrome in Korean adult males and decreased vitamin D level was associated with an increased risk of metabolic syndrome in Korean adult females.

• Preventive Nutrition and Food Science
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• v.8 no.1
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• pp.70-74
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• 2003

This study investigated the relationship of Helicobacter pylori (H. pylori) infection to iron-deficiency anemia in high school girls. Four hundred and fourty-five subjects resided in Ulsan City in Korea were evaluated by questionnaire or blood analysis for serum indicators of iron status, daily nutrient intakes, symptoms of anemia, and H. pylori IgG antibody status. In H. pylori infected subjects, total energy intake of was 1534.14±350.81 kcal (73.0% of the Korean RDA), the iron intake of subjects was 11.38±3.90 mg (71.1% of Korean RDA) and calcium intake was 467.63±175.96 mg (58.3% of the Korean RDA). Carbohydrate (p < 0.05), vitamin A (p < 0.05), vitamin C (p < 0.01) intakes were significantly lower in infected subjects than in non-infected subjects. The prevalence of anemia (hemoglobin (Hb) < 12 g/dL.) in H. pylori infected subjects was 22.7% as compared to 14.7% in non-infected subjects. The mean serum ferritin of infected subjects (21.71±21.50 ng/mL) was significantly lower than in non-infected subjects (p < 0.05) (as was the mean Hb concentration (12.54±1.51 g/dL) and hematocrit (37.99±3.64%)). Total iron binding capacity (TIBC) of H. pylori infected subjects (449.09±78.23 ㎍/dL) was significantly higher than that of non-infected subjects (432.99＋76.15 ㎍/dL) (P < 0.05). The levels of iron, red blood cell (RBC) and transferrin saturation were similar in infected and non-infected subjects. Two symptoms of anemia, 'pale face (p < 0.01)' and 'decreased ability to concentrate (p < 0.005)', were significantly higher in H. pylori infected subjects than in non-infected subjects. High school girls are known to be more vulnerable to iron deficiency than other age groups, and this research demonstrates that infection with H. pylori increases their risk of iron-deficiency anemia.

• Clinical and Experimental Pediatrics
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• v.60 no.2
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• pp.45-49
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• 2017

Purpose: Serum level of 25-hydroxyvitamin D (25-OHD) is considered as the most appropriate marker of vitamin D status. However, only a few studies have investigated the relationship between 25-OHD and parathyroid hormone (PTH) in children. To this end, this study was aimed at evaluating the lowest 25-OHD level that suppresses the production of parathyroid hormone in children. Methods: A retrospective record review was performed for children aged 0.2 to 18 years (n=193; 106 boys and 87 girls) who underwent simultaneous measurements of serum 25-OHD and PTH levels between January 2010 and June 2014. Results: The inflection point of serum 25-OHD level for maximal suppression of PTH was at 18.0 ng/mL (95% confidence interval, 14.3-21.7 ng/mL). The median PTH level of the children with 25-OHD levels of <18.0 ng/mL was higher than that of children with 25-OHD levels ${\geq}$ 18.0 ng/mL (P<0.0001). The median calcium level of children with 25-OHD levels<18.0 ng/mL was lower than that of children with 25-OHD levels${\geq}18.0ng/mL$ (P=0.0001). The frequency of hyperparathyroidism was higher in the children with 25-OHD levels<18.0 ng/mL than in the children with 25-OHD levels${\geq}18.0ng/mL$ (P<0.0001). Hypocalcemia was more prevalent in the children with 25-OHD levels<18.0 ng/mL than in the children with 25-OHD levels${\geq}18.0ng/mL$ (P<0.0001). Conclusion: These data suggest that a vitamin D level of 18.0 ng/mL could be the criterion for 25-OHD deficiency in children at the inflection point of the maximal suppression of PTH.

• Journal of Nutrition and Health
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• v.52 no.5
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• pp.465-474
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• 2019

Purpose: This study examined the association between the serum 25-hydroxyvitamin D concentration and the cognitive functions in Korean elderly. Methods: The subjects were 393 adults aged 60 years or older who participated in the Yangpyeong cohort between July 2009 and August 2010. The subjects were classified into deficiency, insufficiency, or adequacy groups according to the serum 25-hydroxyvitamin D concentration diagnostic criteria suggested by the US Institute of Medicine (IOM). The cognitive function was assessed based on the Korean version of the Mini-Mental State Examination (MMSE-KC). The dietary intake was assessed using the quantitative food frequency questionnaire with 106 food items. Results: The proportions of deficiency, insufficiency, or adequacy in serum 25-hydroxyvitamin D were 6.6%, 44.5%, and 48.9%, respectively. The serum 25-hydroxyvitamin D concentration was significantly higher in men than in women and in outdoor workers than in other occupations. The adequacy group had higher MMSE-KC scores than the other two groups, but not to a significant degree. The proportion of cognitive impairment tended to decrease with increasing serum vitamin D concentration to deficiency, insufficiency, and adequacy (p for trend = 0.029). The deficiency group had a 2.28 times higher risk of cognitive impairment than the adequacy group, but the difference was not statistically significant (OR, 2.28; 95% CI, 0.18 ~ 1.07, p for trend = 0.119). Conclusion: The serum vitamin D concentration tended to be associated with the cognitive function in elderly Koreans living in rural areas. To confirm the associations, further longitudinal studies with large samples were required.

• The Korean Journal of Nuclear Medicine Technology
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• v.24 no.1
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• pp.33-38
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• 2020

Purpose Vitamin D is essential for maintaining bone health, controling cell proliferation or differentiation, strengthening immune function by controlling calcium metabolism in the body. Vitamin D deficiency can lead to increase the risk of rickets, osteoporosis, cardiovascular disease, diabetes and cancer. Especially, South Korea is one of the highest population proportion of vitamin D deficiency. Accurate determination of levels of 25-OH-VitD or 25-OH-VitD3 in blood serum is required for the diagnosis and treatment of vitamin D deficiency. In this study, radioimmunoassay of 25-OH-VitD and 25-OH-VitD3 was performed and compared to evaluate the effectiveness of Vitamin D radioimmunoassay. Materials and Methods Serum 25-OH-VitD and 25-OH-VitD3 levels were measured using radioimmunoassay. The interrelationship, reproducibility and population distribution rate were evaluated. In addition, the internal quality control was performed at Asan Medical Center from April 2017 to June 2019 and the result of external quality control (Interagency proficiency evaluation) of first and second half of 2018 hosted by the Korean Society of Nuclear Medicine Technology (KSNMT). Both tests were measured by same manufacturer's reagent. Results 25-OH-VitD showed a strong positive correlation on 97 samples, as 25-OH-VitD3 x 0.9 + 0.3 (R>0.9). In repeated measurement, the average Diff(%) value of the reproducibility evaluation of 25-OH-VitD and 25-OH-VitD3 were 7.7% and 7.4%, respectively. Population distribution results showed no statistically significant differences(p>0.05). The resultant value of internal quality control, which measured from April, 2017 to June 2019 in Blood test room of Nuclear Medicine at Asan Medical Center, showed average (CV%) 6.2% and 6.8%, respectively. As a result of the external quality control (interagency proficiency evaluation) Z value obtained under 2.0, as shown below; Conclusion The interrelationship, reproducibility, population distribution rate, internal quality control and external quality control between 25-OH-VitD and 25-OH-VitD3 radioimmunoassay shows superior outcome. Radioimmunoassay, which can be alone measured in the blood as 25-OH-VitD or 25-OH-VitD3, is considered suitable screening tests for the diagnosis of vitamin D deficiency.

• Korean Journal of Clinical Pharmacy
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• v.28 no.1
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• pp.10-16
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• 2018

Background: Vitamin D has been associated with sepsis in pediatric and adult patients. The association with neonates is unclear. This systematic review and meta-analysis examined the effect of neonatal and maternal vitamin D levels on neonatal early-onset sepsis. Methods: We searched studies published up to November 2017 in PubMed/Medline, Embase, and the Cochrane Library databases. All studies that reported 25-hydroxyvitamin D levels in neonates with or without early-onset sepsis were included. Meta-analysis was performed using RevMan 5.3 software. Results: Four studies were eligible. The weighted mean difference of 25-hydroxyvitamin D levels in neonates with early-onset sepsis and controls was -7.27 ng/mL (95% confidence interval = -7.62, -6.92). Maternal vitamin D levels in neonates with early-onset sepsis were significantly lower than those in controls (weighted mean difference -7.24 ng/mL, 95% confidence interval -8.45, -6.03). All neonates with early onset sepsis had vitamin D deficiency (25-hydroxyvitamin D <20 ng/mL). Conclusion: Lower neonatal and maternal 25-hydroxyvitamin D levels were associated with neonatal early-onset sepsis. Vitamin D supplementation during pregnancy may be helpful to prevent neonatal early-onset sepsis. The effects of vitamin D supplementation on early-onset sepsis in neonates warrant further study.

• Journal of Nutrition and Health
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• v.46 no.3
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• pp.239-249
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• 2013

Subclinical vitamin $B_{12}$ deficiency is common in the elderly worldwide. We investigated the change of serum vitamin $B_{12}$ concentration with aging and compared anthropometric data and clinical health indicators between normal (${\geq}$ 340 pg/mL) and low (< 340 pg/mL) serum vitamin $B_{12}$ groups in 470 Korean women aged 65 years and over living in a rural area. Serum vitamin $B_{12}$ concentration showed inverse correlation with age (r = -0.0992, p < 0.05). The normal $B_{12}$ group showed significantly (p < 0.05) higher red blood cell count, hemoglobin, and hematocrit compared to the low $B_{12}$ group, however, no difference in mean corpuscular volume was observed between the two groups. The normal $B_{12}$ group showed significantly lower serum homocysteine concentration (p < 0.01) and prevalence of vitamin D (p < 0.01) or folate deficiency (p < 0.001). Bone mineral density (T-score) was significantly higher (p < 0.05) in the normal $B_{12}$ group, compared with that in the low $B_{12}$ group, and showed positive correlation (r = 0.1490, p < 0.01) with serum vitamin $B_{12}$ concentration after adjusting for age, body weight, and body mass index. No differences in anthropometric data, physical activity, and smoking and drinking habits were observed between the two groups. In conclusion, it could be suggested that older female adults with normal serum vitamin $B_{12}$ level would be less anemic and osteoporotic and more resistant to hyperhomocysteinemia associated chronic diseases than those with low serum vitamin $B_{12}$ level.