• 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.

• Nutritional Sciences
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• v.5 no.1
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• pp.20-25
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• 2002

The vitamin $B_{6}$ status of 49 healthy college student (women, aged 20-26 y) was estimated for evaluation of vitamin $B_{6}$ status and the Korean Recommended Dietary Allowance (RDA) for vitamin $B_{6}$. The average daily vitamin $B_{6}$ intake of the subjects was 0.86 $\pm$ 0.289 mg/d or 61.43 $\pm$ 24.10% of Korean RDA. The average ratio of vitamin $B_{6}$ intake to daily protein intake was 0.014 $\pm$ 0.003 mg/g protein. Foods from animal and plaint sources provided 34.25 $\pm$ 18.62% and 65.78 $\pm$ 18.72%, respectively, of total vitamin $B_{6}$. Plasma pyridoxal 5'-phosphate (PLP) concentration was significantly (p<.01 - p<.001) positively correlated to intakes of all other nutrients except vitamin C. However, no significant correlation was found between plasma PLP and nutrient intake. Vitamin $B_{6}$ intake only tended to have a positive correlation with plasma PLP concentration. Plasma total cholesterol was correlated to plasma PLP concentration (p<.05). Plasma PLP had no correlation with levels of glucose, triglyceride, and albumin. These results confirm that the present Korea RDA for vitamin $B_{6}$ of 1.4mg/d based on 0.02 mg/g protein is adequate.

• Pediatric Gastroenterology, Hepatology & Nutrition
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• v.24 no.4
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• pp.403-412
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• 2021

Purpose: This study aimed to determine the serum 25-hydroxy-vitamin D (25(OH)D) status of breastfed infants less than six months old and their mothers, and factors affecting the status. Methods: This cross-sectional study was done on breastfed, term, Filipino infants less than six months old who were seen at local health centers and clinics in an urban area. The serum 25(OH)D levels of these infants and their mothers were determined, and their demographic data, nutritional status, sun exposure behavior, and maternal vitamin D intake were analyzed for correlation using regression models. Results: Among the 131 infants, 101 (77%) had vitamin D deficiency (VDD), which was defined as having 25(OH)D levels <37.5 nmol/L, and 13 (10%) had vitamin D insufficiency (VDI), with levels >37.5-50 nmol/L. Conversely, maternal VDD with levels <50 nmol/L was seen in 31 (24%) mothers and maternal VDI with levels 50-75 nmol/L, in 63 (48%) mothers. Infant age and maternal 25(OH)D status were independent predictors of infant VDD. Infants less than three months old were found to have a six-time increased risk of infant VDD (p=0.004). Infants who had mothers with VDD had a six-time increased risk, whereas those with maternal VDI had a four-time increased risk of infant VDD (p=0.049 and p=0.020, respectively). Conclusion: Both infant and maternal VDD and VDI were seen to be highly prevalent in this tropical, urban community. Young infants and maternal VDD/VDI independently increased the risk of infant VDD, whereas lack of sun exposure of the mothers increased the risk for maternal VDI.

• Nutrition Research and Practice
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• v.14 no.2
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• pp.117-126
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• 2020

BACKGROUND/OBJECTIVES: Vitamin D and zinc are recognized for their roles in immune-modulation, and their deficiencies are suggested to be important risk factors for childhood infections. This study, therefore, undertook to assess the occurrence of infections in rural Indian schoolchildren, subsequent to daily supplementation with vitamin D-calcium or zinc for 6 months. SUBJECTS/METHODS: This was a randomized, double-blind, placebo-controlled trial in apparently healthy 6-12 year-old rural Indian children, recruited to 3 study arms: vitamin D arm (1,000 IU D3 - 500 mg calcium, n = 135), zinc arm (10 mg, n = 150) and placebo arm (n = 150). The infection status was assessed using a validated questionnaire, and the biochemical parameters of serum 25(OH)D and serum zinc were measured by ELISA and colorimetry, respectively. The primary outcome variable was occurrence of infections (upper respiratory and total infections). RESULTS: Serum 25(OH)D concentration in the vitamin D arm improved significantly by 34%, from 59.7 ± 10.9 nmol/L to 80 ± 23.3 nmol/L (P < 0.0001), but no improvement was observed for serum zinc concentration. While there was significant increase in the percentage of children reporting no or mild upper respiratory tract infections (URTI) and total infections (TI) in all three groups, improvements in the supplemented groups were similar to the placebo group. However, the vitamin D arm reported lower URTI and TI status in the vitamin D sufficient versus insufficient children. Also, URTI and TI status were found to be significantly (P < 0.0001) lower in children with improved 25(OH)D versus unchanged 25(OH)D. CONCLUSIONS: Vitamin D-calcium supplementation helped to improve the vitamin D status but exerts no effect on the occurrence of infections when compared to the placebo group. Improvement in the serum 25(OH)D concentrations and attainment of vitamin D sufficiency may exert a beneficial effect on the infection status and needs to be investigated further. To evaluate the efficacy of zinc supplementation, higher dosages need to be administered in future studies.

• Korean Journal of Community Nutrition
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• v.20 no.2
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• pp.120-128
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• 2015

Objectives: The purpose of this study was to examine the relative impact of seasonal differences and age on dietary vitamin D intakes, outdoor activity time and serum vitamin D status among Korean postmenopausal women. Methods: A cross-sectional study was conducted with 164 free-living postmenopausal women (mean age=55.4 years) in Daegu, Korea. Dietary intake, daily physical activity patterns and fasting blood samples were collected during summer and winter. We compared the results from 75 women during summer and 89 women during winter. Dietary intake of vitamin D was assessed by 24-hour recall method. Daily outdoor activity time was derived from physical activity diary. Results: The average dietary intake of vitamin D of the participants was $3.7{\mu}g$ during summer, $3.3{\mu}g$ during winter, showing no significant difference between the two seasons. The average time spent on outdoor activities was not significantly different between summer ($=35.1{\pm}75.0min/d$) and winter ($=48.5{\pm}76.8min/d$). The average serum 25-(OH) vitamin D concentrations of participants was $17.5{\pm}7.5ng/mL$ in the summer and $13.4{\pm}4.3ng/mL$ in the winter, showing no significant differences by season. Dietary intake of vitamin D was not related to age. When total subjects were divided into two groups by age, the average serum 25-(OH) vitamin D concentration was significantly higher in older group (p=0.047) and time spent on outdoor activities was also (p=0.018) significantly higher in the older group. Conclusions: In order to improve the current vitamin D status of Korean postmenopausal women, nutrition education programs should focus more on adequate intake of vitamin D, while maintaining enough outdoor activities over the season.

• Journal of Korea Entertainment Industry Association
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• v.13 no.5
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• pp.139-143
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• 2019

The aim of this study was to assess the association of vitamin D and urine microalbumin/creatinine (uACR) and obesity. The study subjects were Korean adults 20 years or older (n = 4,948) who participated in the Korea National Health and Nutrition Examination Survey 2012. Analysis of covariance test adjusted for covariates were performed for uACR levels in relation to vitamin D status [vitamin D deficient, 25(OH)D < 10 ng/dL; vitamin D insufficient, 25(OH)D ≥ 10, < 20 ng/dL; vitamin D sufficient, 25(OH)D ≥ 20 ng/dL]. The key study results were as follows: First, in the populations without obesity (BMI < 25 kg/m²), uACR levels were decreased with the increasing of vitamin D status (p < 0.001) after adjusting for relevant variables. Second, in the populations with obesity (BMI ≥ 25 kg/m²), the association between uACR levels and vitamin D status was not significant (p = 0.659). In conclusion, urine microalbumin/creatinine levels were inversely associated with vitamin D status in Korean adults without obesity, but not in Korean adults with obesity.

• Research in Community and Public Health Nursing
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• v.28 no.3
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• pp.251-259
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• 2017

Purpose: This study aims to examine the influence of vitamin D and calcium on depression and cognitive function of the elderly living alone in a city. Methods: The participants were registered in eight senior centers in S city and they had lived alone. Data were collected between November 28, 2014 and March 7, 2015. A total of 155 people participated in data collection to measure the serum vitamin D, the serum calcium, depression, and cognitive function. The data were analyzed with t-test, ANOVA, Pearson's correlation and multiple regression analysis. Results: There were significant differences in depression according to gender and perceptions of health status. Depression correlated significantly with the serum calcium and perceptions of health status, and a stepwise regression analysis showed that the perceptions of health status were significant. There were significant differences in cognitive function according to education level and age. Cognitive function correlated significantly with the serum vitamin D and a stepwise regression analysis showed that education level and age were significant. Conclusion: Consequently, elderly people with poor perceptions of their health status need a depressive intervention program and those with a higher age and lower level of education need a cognitive function intervention program.

• Journal of Obesity & Metabolic Syndrome
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• v.27 no.4
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• pp.223-232
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• 2018

Vitamin D, a free sunshine vitamin available for mankind from nature, is capable to avert many health-related critical circumstances. Vitamin D is no more regarded as a nutrient involved in bone metabolism alone. The presence of vitamin D receptor in a number of tissues implies that vitamin D has various physiological roles apart from calcium and phosphorus metabolism. Low serum vitamin D has been found to be associated with various types of metabolic illness such as obesity, diabetes mellitus, insulin resistance, cardiovascular diseases including hypertension. Various studies reported that vitamin D insufficiency or deficiency in linked with metabolic syndrome risk. This review focuses on various metabolic diseases and its relationship with serum vitamin D status.

• The Korean Journal of Physiology and Pharmacology
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• v.17 no.5
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• pp.385-392
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• 2013

Vitamin D deficiency is prevalent, primarily due to limited sun exposure, which may be observed in urban areas, or as a result of modern lifestyles. Common myths about vitamin D persist, including that it is mostly obtained from the diet and is only essential for bone and mineral homeostasis. Nonetheless, advances in biomedical science suggest that vitamin D is a hormone that is integral to numerous physiologic functions in most cells and tissues. Therefore, abnormal vitamin D levels may contribute to health disturbances. A number of recent reports on potential associations between vitamin D deficiency and cardiovascular disease have highlighted its role in this system. A focus over the previous decade has been to better understand the mechanisms behind vitamin D regulation and the pathophysiology associated with suboptimal vitamin D levels. Vitamin D deficiency is highly associated with the incidence of cardiovascular diseases, even when considering other well-known risk factors. In this process, the renin-angiotensin system is disrupted, and hypertension and endothelial dysfunction contribute to the risk of cardiovascular disease. Likewise, clinical outcomes upon the normalization of vitamin D levels have been investigated in different patient populations. It makes sense that vitamin D supplementation to improve vitamin D status among vitamin D-deficient individuals could be useful without requiring a sudden lifestyle change. This manuscript provides a brief overview of vitamin D metabolism and the vitamin D receptor. It also summarizes the current clinical research relating to vitamin D supplementation and its effects on hypertension and endothelial dysfunction in cardiovascular medicine.

• Journal of Nutrition and Health
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• v.29 no.7
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• pp.747-757
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• 1996

In this study, the serum level of 25-hydroxyvitamin D(25-(OH)D) was measured by high pressure liquid chromatography(HPLC), and factors affecting it were investigated in 72 young adults age ranging from 21 years to 39 years with normal bone density. The mean level of serum 25-(OH)D was 20.0$\pm$6.8ng/ml in males and 26.1$\pm$12.3ng/ml in females, which was significantly higher in females (p<0.01). The serum level of parathyroid hormone(PTH) showed a negative correlation with that of 25-(OH)D(p<0.05). Time spent outdoors in a day correlated positively with the serum level of 25-(OH)D(p<0.01). During the day, a specific time between 12:00 a.m. and 2:00 p.m. showed the most significant correlation with the level of 25-(OH)D(p<0.005). Among the nutrients studied, fat and vitamin D intake were positively correlated with the serum 25-(OH)D level. Stepwise multiple regression analysis showed that the serum level of 25-(OH)D could be fit by vitamin D intake(34.7% explained), serum PTH level (27.3% explained) and the time spent outdoors during the specific time(28.4% explained).1996)