Comparison of Sunlight Exposure and Vitamin D Supplementation on Serum 25-hydroxyvitamin D Levels

Study Overview
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Brief Summary
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This study aimed to compare the effects between sunlight exposure and oral vitamin D supplementation on serum 25-hydroxyvitamin D concentration and metabolic markers in Korean young adults.

Official Title
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Comparison of Sunlight Exposure and Oral Vitamin D Supplementation on Serum 25-hydroxyvitamin D Concentration and Metabolic Markers in Korean Young Adults: a Randomized Clinical Trial

Conditions
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Vitamin D Deficiency, Cardiometabolic Risk Factors

Intervention / Treatment
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* Behavioral: Sunlight Exposure
* Dietary Supplement: Vitamin D Supplementation
* Other: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Serum 25(OH)vitamin D < 12ng/mL age between 18 and 39 years Korean men and women Exclusion Criteria: Vitamin D supplementation within 2 months Photosensitivity or UV allergy History of hyperparathyroidism/hypercalciuria/kidney stone/skin cancer and other cancer Under medication for hypertension, dyslipidemia, and diabetes Intake of photosensitive medicine during study period Exposure of strong UV (e.g., beach, sun tanning) during study period Pregnant/breast-feeding women

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 39 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Sunlight Exposure<br>Everyday sunlight exposure around noon for 20-30 minutes for 8 weeks | Behavioral: Sunlight Exposure<br>* Everyday sunlight exposure around noon for 20-30 minutes for 8 weeks Completing a Sun Diary after sunlight exposure<br>|
| Experimental: Vitamin D Supplementation<br>Supplementation of vitamin D3 500 IU/day for 8 weeks | Dietary Supplement: Vitamin D Supplementation<br>* - Supplementation of vitamin D3 500 IU/day for 8 weeks<br>|
| Placebo Comparator: Placebo<br>Intake of placebo for 8 weeks | Other: Placebo<br>* - Intake of placebo for 8 weeks<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Serum 25(OH)D | Changes in serum 25(OH)D levels in ng/mL | Baseline, 4 week, and 8 week | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| BMI | Weight and height will be combined to report BMI in kg/m^2 | Baseline, 4 week, and 8 week | 
| Systolic blood pressure | Systolic blood pressure changes in mmHg | Baseline, 4 week, and 8 week | 
| Diastolic blood pressure | Diastolic blood pressure changes in mmHg | Baseline, 4 week, and 8 week | 
| Lipid panel | Serum total cholesterol, triglycerides, HDL cholesterol, and LDL cholesterol in mg/dL | Baseline and 8 week | 
| Fasting glucose | Serum fasting glucose in mg/dL | Baseline and 8 week | 
| AST | Serum AST levels in mg/dL | Baseline and 8 week | 
| ALT | Serum ALT levels in mg/dL | Baseline and 8 week | 
| GGT | Serum AST, ALT, and GGT levels in mg/dL | Baseline and 8 week | 
| Intact PTH | Serum intact PTH levels in mg/dL | Baseline and 8 week | 
| Whole body BMD and BMC | Whole body BMD (g/cm^2) and BMC (kg) measured by DEXA | Baseline and 8 week | 
| Lean body mass, fat mass, and percent fat | Lean body mass (kg), fat mass (kg), and percent fat (%) measured by DEXA | Baseline and 8 week | 
| Lean body mass, muscle mass, skeletal muscle mass, fat mass, and percent fat | Lean body mass (kg), muscle mass (kg), skeletal muscle mass (kg), fat mass (kg), and percent fat (%) measured by body impedance analysis | Baseline, 4 week, and 8 week | 
| EQ-5D-5L | Quality of life measured using EQ-5D-5L scale. The EQ-5D is a standardised measure of health status developed by the EuroQol Group in order to provide a simple, generic measure of health status. In description part, health status is measured in terms of five dimensions (5D); mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. The respondents self-rate their level of severity for each dimension using three-level (EQ-5D-3L) or five-level (EQ-5D-5L) scale. The 5-level version of EQ-5D (EQ-5D-5L) was developed to improve such constraints of the three-level scale. EQ-5D-5L scale can define 3,125 (=5^5) different health states, and the 5-digit number can be converted into a preference weight which is also referred to as a single weighted index score. The index score of a value set derived from the general population sample can be regarded as a societal valuation of the respondent's health state in that country. | Baseline, 4 week, and 8 week |