• Journal of the East Asian Society of Dietary Life
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• v.16 no.3
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• pp.292-298
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• 2006

Modification of the diet during childhood and adolescence may be an effective strategy for maximizing the peak bone mass. Many supplementation studies have suggested a positive effect of the increased vitamin D intake on the bone mineral status in the elderly. However to date all studies have been conducted on old men and postmenopausal women. The aim of this study was to examine the effects of vitamin D supplementation on the bone mineral density and bone mineral content in growing rats. Twenty Sprague-Dawley female rats were divided into two groups; Control, and vitamin D supplementation. The bone mineral density(BMD) and bone mineral content(BMC) were measured using PIXImus in the spine and femur. Vitamin D supplementation did not affect the level of weight gain, mean food intake and food efficiency ratio. In addition, vitamin D supplementation had no added effect on the spine and femur BMD, and BMC. There were no significant differences in the spine BMD/weight and BMC/weight between the groups, but the spine BMD/weight and BMC/weight was 11 % higher in the vitamin D supplementation group. The femur BMD/weight and femur BMC/weight were significantly higher in the vitamin D supplementation group 9 weeks after the experiment. These results provide evidence of the beneficial effects of vitamin D supplementation on the BMD during the growth period.

• Nutrition Research and Practice
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• v.9 no.2
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• pp.158-164
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• 2015

BACKGROUND/OBJECTIVES: Vitamin D deficiency is common in hemodialysis patients. The aim of this study was to identify whether or not sun exposure and dietary vitamin D intake have effects on serum 25-hydroxyvitamin D (25(OH)D) status in hemodialysis (HD) patients. The objective was to identify the main determinants of serum vitamin D status in the study subjects. SUBJECTS/METHODS: A cross-sectional study of 47 HD patients (19 males and 28 females) was performed. We assessed serum 25(OH)D and $1,25(OH)_2D$ levels between August and September 2012 and analyzed the prevalence of vitamin D deficiency in HD patients. To evaluate the determinants of serum 25(OH)D levels, we surveyed dietary vitamin D intake, degree of sun exposure, and outdoor activities. To compare biological variables, serum 25(OH)D was stratified as below 15 ng/ml or above 15 ng/ml. RESULTS: Mean 25(OH)D and $1,25(OH)_2D$ levels were $13.5{\pm}5.8ng/ml$ and $20.6{\pm}11.8pg/ml$, respectively. The proportions of serum 25(OH)D deficiency (< 15 ng/ml), insufficiency (15-< 30 ng/ml), and sufficiency (${\geq}30ng/ml$) in subjects were 72.4%, 23.4%, and 4.3%, respectively. Prevalence of vitamin D deficiency in female patients was 78.6%, whereas that in males was 63.2% (P = 0.046). Vitamin D intake and sun exposure time were not significantly different between the two stratified serum 25(OH)D levels. Dietary intake of vitamin D did not contribute to increased serum 25(OH)D levels in HD patients. The main effective factors affecting serum 25(OH)D status were found to be the sun exposure and active outdoor exercise. CONCLUSIONS: Hypovitaminosis D is common in HD patients and is higher in females than in males. Sun exposure is the most important determinant of serum 25(OH)D status in HD patients.

• 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.

• Journal of the Korean Dietetic Association
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• v.23 no.1
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• pp.39-53
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• 2017

Insufficient vitamin D intake is a major health problem around the world. Recently, many studies have suggested that vitamin D intake may influence insulin resistance. However, little is known about the association between vitamin D and diabetes mellitus. The aim of this study was to investigate the association between serum 25-hydroxy vitamin D (25(OH)D) levels and diabetes mellitus in Korean adults. This study was a cross-sectional analysis of 3,686 participants of the Korean National Health and Nutrition Examination Survey (KNHANES) 2013~2014 aged 19 years and higher. The results showed that the mean serum 25-hydroxy vitamin D (25(OH)D) level in Korean adults was 16.77 ng/mL, and 74.2% of them had an insufficient serum 25-hydroxy vitamin D (25(OH)D) level (below 20 ng/mL). In normal and pre-diabetic groups, the serum 25-hydroxy vitamin D (25(OH)D) level significantly increased with age (P<0.001), but there was no significant difference relative to age in the diabetic group. Low vitamin D levels (25-hydroxy vitamin D < 10 ng/mL) were associated with increased fasting blood glucose levels, compared with optimal vitamin D levels (25-hydroxy vitamin D > 30 ng/mL), after adjusting for variables that may affect fasting blood glucose, but this result was not significant. In conclusion, although no significant association was observed between diabetes prevalence and vitamin D levels in this study, further studies are needed because the effect of vitamin D on diabetes remains controversial. This nutrient plays a crucial role in the body, and levels are insufficient in the Korean population.

• Journal of Nutrition and Health
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• v.38 no.1
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• pp.76-81
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• 2005

The effects of the amount of red pepper intake per a day on the capsaicin threshold, nutrient intake, and anthropo-metric measurements were investigated in 100 female students of university. Three 24-hour recalls were performed to estimate usual nutrient and red pepper intake of free-living participants. The solutions containing capsaicin at concentration of 0.05, 0.1, 0.2, 0.3, 0.4, 0.5ppm used for the evaluation of hot-taste detection threshold. Subjects were asked to recognize the burning sensation after tasting l0ml of each test solution in ascending order of capsaicin concentrations. Mean intake of red pepper was 4.6 g/d and the capsaicin threshold was 0.27 ppm. The detection threshold for capsaicin was correlated with the amount of pepper intake per a day. Red pepper intake was correlated with energy, protein, lipid, carbohydrate, Iron, vitamin A, vitamin B$_2$ niacin, and vitamin E intakes. However, it was not correlated with intake of calcium, vitamin B$_1$ or vitamin C. The red pepper intake was negatively correlated with fat mass and waist girth and the capsaicin threshold was also negatively correlated with pulse. In conclusion, red pepper intake was associated with nutrient intake and capsaicin threshold whereas it was negatively correlated with fat mass and waist girth.

• Clinical and Experimental Reproductive Medicine
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• v.51 no.2
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• pp.125-134
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• 2024

Objective: Vitamin D deficiency is a major problem for human health worldwide. The mechanisms of vitamin D in the male reproductive system are unknown. After coronavirus disease 2019 (COVID-19) vaccines were developed, doubts were raised about their possible effects on male fertility. Based on vitamin D's function in the immune system, its potential role as an adjuvant for COVID-19 vaccines is intriguing. The aims of this study were to assess the effects of vitamin D first on sperm parameters and sex hormones, and then as an immune adjuvant on sperm parameters and sex hormones after study participants had received their second doses of COVID-19 vaccines. Methods: Phase 1 (before the COVID-19 pandemic) included 72 men with idiopathic infertility, and phase 2 had 64 participants who received two doses of COVID-19 vaccines. Both groups were instructed to take 50,000 IU of vitamin D twice monthly for 3 months. Sperm parameters and sex hormones were assessed pre-and post-supplementation. Results: Regular vitamin D intake for 3 months significantly increased the participants' vitamin D levels (p=0.0001). Both phases showed a positive correlation between vitamin D intake and sperm parameters. Vaccination had no negative effects on sperm parameters and sex hormones. Vitamin D was associated with follicle-stimulating hormone (p=0.02) and testosterone (p=0.0001) in phase 2 after treatment. Conclusion: Our results support vitamin D supplementation as an immune adjunct to COVID-19 vaccination for improving sperm parameters and hormone levels. COVID-19 vaccination is not harmful for male fertility potential, and vitamin D is an effective factor for male fertility.

• Journal of Environmental Health Sciences
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• v.44 no.2
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• pp.188-195
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• 2018

Objectives: This study aimed to investigate the association between vitamin D deficiency and the risk of diabetes mellitus, and also examined whether their association is differed by sex and age. Methods: We analyzed the data from 28,135 subjects ${\geq}20years$ old who were registered for the Korea National Health and Nutrition Examination Survey (KNHANES) 2008-2014. Vitamin D was measured using serum 25-hydroxyvitamin D (25(OH)D) concentrations. Results: After adjusting for potential confounders (age, sex, education, income, total energy intake, smoking, physical activity, body mass index, and waist circumference), lower vitamin D was dose-dependently associated with a higher risk of diabetes mellitus (p-trend=0.004). When compared with the sufficient group (25(OH)D ${\geq}30ng/mL$), the severe deficient group (25(OH)D <10 ng/mL) had 1.46 (95% CI 1.11-1.94) odds ratio for the risk of diabetes mellitus. This association was markedly strong in men and adults aged ${\geq}40$, whereas no significant association was observed in women and adults aged <40. Conclusions: We found that vitamin D deficiency may be associated with an increased risk for diabetes mellitus in Korean adults. Our findings suggest that intake of higher vitamin D may help reduce the risk of diabetes mellitus.

• Food Science and Preservation
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• v.30 no.1
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• pp.109-121
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• 2023

This study was conducted to evaluate vitamin D intake of Koreans in a total diet study (TDS) and to determine the effect of irradiation on vitamin D synthesis in mushrooms. For analysis, sample were saponified and extracted with hexane, and vitamin D was quantified by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Based on the validation results, the recovery of the National Institute of Standards and Technology (NIST) standard reference sample (SRM) 1849a was 96.7% and the z-score of -1.6 was obtained by the Food Analysis Performance Assessment Scheme (FAPAS) proficiency test (PT) 21115. Vitamin D₂ was not detected in any samples, and the highest level of vitamin D₃ was detected in mackerel and anchovies ranging from 24.2 to 120.2 ㎍/kg. The mean daily intake of vitamin D was 0.99 ㎍/day, as estimated from the vitamin D contents of the analyzed foods and their corresponding intake. The adequate intake (AI) of vitamin D based on the Dietary reference intakes for Koreans provided by the Ministry of Health and Welfare is 5-15 ㎍/day for Koreans aged 6 to 75 years. Compared with this AI, vitamin D intake of Koreans estimated in this study was inadequate. For that, the increased vitamin D content in ultraviolet (UV)/sun light irradiated mushrooms warrants further research to increase vitamin D intake of Koreans through diet.

• Nutritional Sciences
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• v.7 no.2
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• pp.107-112
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• 2004

This study investigated the interactions of bone health with several variables such as outdoor activity hours, nutritional status including habitual intake of calcium andvitamin D status in 72 high school girls aged 16-17 yearsattending day classes or night classes. The subjects consisted of 39 day-class students and 33 night-class students. Dietaty nutrient intakes were estimated using the 24-hour recall method. The daily activities of each subject were assessed using an activity questionnaire. Urinary calcium and creatinine excretion were assayed from subjects' 24-hoururine, while 25-OH-vitamin D[25-(OH)-D] and osteocalcin were measured from the subjects' fasting blood. Intake of energy, iron, vitamin A and vitamin C were worse in the night-class students. There was no significant difference in dietary calcium between the subjects in the different class types. Time spent on outdoor activities was significantly less in subjects attending night classes. Urinary calcium excretion of the night-class subjects was significantly higher than that of the day-class subjects (p<0.05). There was no significant difference in serum 25-(OH)-D level according to class type. Serum osteocalcin for night-class subjects was significantly higher than that for day-class subjects (p<0.01). It appeared that the night-class students had poorer dietary habits as well as fewer outdoor activities. Even though the estimated bone health of both groups of subjects appeared to be normal, the overall nutritional intake and duration of outdoor activities appeared to be important for maintaining bone health and lowering the future risk of osteoporosis.

• Journal of Korean Biological Nursing Science
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• v.18 no.3
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• pp.185-191
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• 2016

Purpose: The purpose of this study is to understand the effect of taking calcium/vitamin D supplements and performing Taekkyeon exercises on the frailty of the elderly targeting a vulnerable senior social group. Methods: A total of 124 people aged 65 and older consisting of 60 persons in the experimental group, and 64 persons in the control group participated in this study, and this study is a non-equivalent control group pre/post-test design quasi-experimental study. This study analyzed the homogeneity between the experimental group and the control group using a chi-square test and t-test while analyzing the difference in the degree of frailty and bone density with the practice of Taekkyeon and a calcium agent using t-test and GEE. Results: The study results showed that the frailty and bone density of the experimental group significantly improved. Conclusion: Through this study, it was confirmed that calcium/vitamin D intake and Taekkyeon exercises were an effective intervention which strengthened the elderly's physical condition.