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

• Asian Spine Journal
• /
• v.12 no.6
• /
• pp.1127-1145
• /
• 2018

Several theories have been proposed to explain the etiology of adolescent idiopathic scoliosis (AIS) until present. However, limited data are available regarding the impact of vitamin D insufficiency or deficiency on scoliosis. Previous studies have shown that vitamin D deficiency and insufficiency are prevalent in adolescents, including AIS patients. A series of studies conducted in Hong Kong have shown that as many as 30% of these patients have osteopenia. The 25-hydroxyvitamin D3 level has been found to positively correlate with bone mineral density (BMD) in healthy adolescents and negatively with Cobb angle in AIS patients; therefore, vitamin D deficiency is believed to play a role in AIS pathogenesis. This study attempts to review the relevant literature on AIS etiology to examine the association of vitamin D and various current theories. Our review suggested that vitamin D deficiency is associated with several current etiological theories of AIS. We postulate that vitamin D deficiency and/or insufficiency affects AIS development by its effect on the regulation of fibrosis, postural control, and BMD. Subclinical deficiency of vitamin K2, a fat-soluble vitamin, is also prevalent in adolescents; therefore, it is possible that the high prevalence of vitamin D deficiency is related to decreased fat intake. Further studies are required to elucidate the possible role of vitamin D in the pathogenesis and clinical management of AIS.

• Nutrition Research and Practice
• /
• v.16 no.sup1
• /
• pp.57-69
• /
• 2022

BACKGROUND/OBJECTIVES: Vitamin D is produced in the skin during sun exposure and is also ingested from foods. The role of vitamin D needs to be considered in the prevention and management of various diseases. Moreover, since the majority of Koreans spend their days indoors, becoming susceptible to the risk of vitamin D deficiency. The current study aims to prepare a basis for determining dietary reference intake of vitamin D in Korea, by reviewing the evidence against various diseases and risks. MATERIALS/METHODS: Literature published in Korea and other countries between 2014 and 2018 was prioritized based on their study design and other criteria, and evaluated using the RoB 2.0 assessment form and United States Department of Agriculture Nutrition Evidence Library Conclusion Statement Evaluation Criteria. RESULTS: Of the 1,709 studies, 128 studies were included in the final systematic analysis after screening. To set the dietary reference intakes of vitamin D based on the selected articles, blood 25(OH)D levels and indicators of bone health were used collectively. Blood vitamin D levels and ultraviolet (UV) exposure time derived from the Korean National Health and Nutrition Examination Survey were analyzed to establish the dietary reference intakes of vitamin D for each stage of the life cycle. The adequate intake levels of vitamin D, according to age and gender, were determined to be in the range of 5-15 ㎍/day, and the tolerable upper intake level was established at 25-100 ㎍/day. CONCLUSIONS: The most important variable for vitamin D nutrition is lifestyle. A balanced diet comprising foods with high contents of vitamin D is important, as is vitamin D synthesis after UV exposure. The adequate intake level of vitamin D mentioned in the 2015 Dietary Reference Intakes for Korean (KDRI) remained unchanged in the 2020 KDRI for the management of vitamin D nutrition in Koreans.

• Clinical Psychopharmacology and Neuroscience
• /
• v.16 no.4
• /
• pp.383-390
• /
• 2018

Objective: Autism spectrum disorder (ASD) is a complex neurodevelopmental syndrome with an increasingly prevalent etiology, yet not fully understood. It has been thought that vitamin D, complex B vitamin levels and homocysteine are associated with environmental factors and are important in ASD. The aim of this study was to examine serum vitamin D, vitamin D receptor (VDR), homocysteine, vitamin B6, vitamin B12 and folate levels in ASD. Methods: In this study, serum vitamin D and VDR, homocysteine, vitamins B6, B12 and folate levels were determined in 60 patients with ASD (aged 3 to 12 years) and in 45 age-gender matched healthy controls. In addition, calcium, phosphorus and alkaline phosphatase, which are associated with vitamin D metabolism, were measured from serum in both groups. ASD severity was evaluted by the Childhood Autism Rating Scale (CARS). Results: Serum vitamin D and VDR were substantially reduced in patients with ASD in comparision to control group. However, homocysteine level was significantly higher and vitamin B6, vitamin B12 and folate were also reduced in patients with ASD. Total CARS score showed a positive association with homocysteine and a negative correlation with vitamins D,B6, B12, folate and VDR. Conclusion: This comprehensive study, which examines many parameters has shown that low serum levels of vitamins D, B6, B12, folate and VDR as well as high homocysteine are important in the etiopathogenesis of ASD. However, further studies are required to define the precise mechanism(s) of these parameters and their contributions to the etiology and treatment of ASD.

• Clinical and Experimental Pediatrics
• /
• v.52 no.10
• /
• pp.1082-1089
• /
• 2009

Vitamin D is an important fat-soluble vitamin that functions as a prohormone and affects bone mineralization and calcium homeostasis. Vitamin D deficiency causesboth musculoskeletal manifestations, including rickets, and extra-musculoskeletal symptoms. Because vitamin D is naturally present in only some foods, intake of daily foods cannot meet the dietary reference intake for vitamin D. Sunlight is the main source of vitamin D in humans therefore, the lack of sunlight can easily cause vitamin D deficiency in children and adolescents. Vitamin D deficiency can be diagnosed on the basis ofits typical clinical manifestation, laboratory tests, and radiologic findings. Detection of vitamin D deficiency in children or adolescents necessitates the simultaneous administration of vitamin D and calcium supplements. To prevent vitamin D deficiency, 200 IU of daily vitamin D intake is recommended in infants, and 400 IU of daily vitamin D intake is recommended in Korean children and adolescents.

• Korean Journal of Poultry Science
• /
• v.50 no.2
• /
• pp.73-80
• /
• 2023

Vitamin D3 is an essential nutrient which plays an important role in calcium metabolism for eggshell formation, in calcium and phosphorus metabolism for bone mineralization, and in maintaining host immunity. Although there have been a great deal of studies investigating the role of vitamin D3 in eggshell quality and vitamin D3 contents in eggs, no attempts have been made to monitor the eggshell quality and vitamin D3 contents in eggs at farm level. Thus, this survey was conducted to measure eggshell quality and vitamin D3 contents in eggs laid from laying hens fed diets containing different levels of vitamin D3. Eggs from four commercial laying hen farms were sampled before and 1, 2, 3 and 5 weeks after provision of the vitamin D3-enriched diets added with the level of 16,500 IU and 29,000 IU. Dietary vitamin D3 did not affect the eggshell color and breaking strength, but increase the eggshell thickness. In addition, vitamin D3 contents in eggs were elevated as vitamin D3 in diets was increased. It is concluded that addition of dietary vitamin D3 into the diets of laying hens at the commercial laying hen farms could improve eggshell quality and vitamin D3 contents in eggs. It is expected that the prediction equation for egg vitamin D3 contents might be produced if more data on vitamin D3 contents in diets and eggs at the farms are to be analyzed.

• The Journal of Pediatrics of Korean Medicine
• /
• v.26 no.1
• /
• pp.70-78
• /
• 2012

Objectives Recently, vitamin D supplements to breast-fed infants are being encouraged in Korea, and other countries. However, the reliability and validity assessment of supplements is insufficient. Therefore, this study suggests new Korean guidelines for vitamin D supplements of breast-fed infant. Methods The roles of Vitamin D for bone metabolism in children and the correlation between breast milk and Vitamin D were examined throughout domestic and international literature review. In addition, the efficacy and safety of vitamin D supplements were reviewed. Results Preventive effects of rickets by vitamin D supplementation remain unclear. Furthermore, concerns about the safety of vitamin D supplements intake have been raised. Korean guideline suggests breast-fed infants can get vitamin D through the skin safely, but maternal intake of vitamins through sunbath and diet is more effective and safe. Conclusions Limiting sunlight excessively and applying foreign countries' medical guideline for vitamin D supplements are not valid to apply as a domestic guideline for Korean breast-fed infants without considering ethnic and cultural characteristics.

• Korean Journal of Community Nutrition
• /
• v.20 no.2
• /
• pp.120-128
• /
• 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 Korean Public Health Nursing
• /
• v.31 no.1
• /
• pp.84-96
• /
• 2017

Purpose: Vitamin D is a fundamental element for bone metabolism. Recently vitamin D deficiency has been implicated in various diseases such as a cardiovascular disease, diabetes, and cancers. The aim of this study was to identify the risk factors associated with serum vitamin D deficiency among women office workers. Methods: We selected 369 women office workers using the secondary data of the 5th National Health & Nutrition Examination Survey 2010-2012. Data was analyzed by logistic regression of complex sampling design. Results: Women office workers with vitamin D deficiency, defined serum 25-hydroxyvitamin D concentration < 10ng/mL, were 12.5%. The risk factors for vitamin D deficiency were 20s aged group, married state and more than 40 working hours a week. The risk of vitamin D deficiency was decreased in those with alcohol drinking 1 to 4 times a month. The education level, income, region, smoking, physical activity and sun exposure time did not affect the risk of vitamin D deficiency significantly. Conclusion: Development of vitamin D deficiency prevention educational programs are required for women office workers who more than 40 hours a week in 20s. It should be considered health education including sun exposure duration and behavior.

• Clinical and Experimental Pediatrics
• /
• v.58 no.11
• /
• pp.427-433
• /
• 2015

Purpose: We investigated the vitamin D status of preterm infants to determine the incidence of vitamin D deficiency. Methods: A total of 278 preterm infants delivered at Kyungpook National University Hospital between January 2013 and May 2015 were enrolled. The serum concentrations of calcium, phosphorous, alkaline phosphatase, and 25-hydroxyvitamin D (25-OHD) were measured at birth. We collected maternal and neonatal data such as maternal gestational diabetes, premature rupture of membranes, maternal preeclampsia, birth date, gestational age, and birth weight. Results: Mean gestational age was $33^{+5}{\pm}2^{+2}$ weeks of gestation and mean 25-OHD concentrations were $10.7{\pm}6.4ng/mL$. The incidence of vitamin D deficiency was 91.7%, and 51.1% of preterm infants were classified as having severe vitamin D deficiency (25-OHD<10 ng/mL). The serum 25-OHD concentrations did not correlate with gestational age. There were no significant differences in serum 25-OHD concentrations or incidence of severe vitamin D deficiency among early, moderate, and late preterm infants. The risk of severe vitamin D deficiency in twin preterm infants was significantly higher than that in singletons (odds ratio, 1.993; 95% confidence interval [CI], 1.137-3.494, P=0.016). In the fall, the incidence of severe vitamin D deficiency decreased 0.46 times compared to that in winter (95% CI, 0.227-0.901; P=0.024). Conclusion: Most of preterm infants (98.9%) had vitamin D insufficiency and half of them were severely vitamin D deficient. Younger gestational age did not increase the risk of vitamin D deficiency, but gestational number was associated with severe vitamin D deficiency.