Vitamin D Supplementation and Immunity/Physical Performance

Study Overview
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Brief Summary
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The purpose of this study is to examine the effect of vitamin D supplementation on vitamin D status, immunity and physical performance.

Detailed Description
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Vitamin D plays a key role in bone mineralisation and has been linked to immune defence maintenance and muscle function. Vitamin D is primarily obtained from endogenous synthesis in response to skin sunlight exposure and follows a seasonal pattern; whereby, vitamin D levels peak at the end of the summer and fall to a trough during winter. If winter vitamin D levels can be increased to match those found in summer using supplementation, it is proposed sufficient vitamin D levels will improve physical performance and reduce susceptibility to illness in military recruits.

Official Title
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The Effect of Vitamin D Supplementation on Vitamin D Status, Immunity and Physical Performance

Conditions
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Vitamin D Status

Intervention / Treatment
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* Dietary Supplement: Oral Vitamin D3
* Dietary Supplement: Placebo Oral Vitamin D3
* Radiation: Solar simulated radiation (SSR)
* Radiation: Placebo SSR


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Passed medical assessment by medical doctor Exclusion Criteria: Medically deferred by medical doctor Regular sun bed use Holiday in a hot sunny climate in <3 months Regular vitamin D supplementation

Ages Eligible for Study
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Minimum Age: 17 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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Male

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: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Solar simulated radiation (SSR)<br>Solar simulated radiation (SSR) | Radiation: Solar simulated radiation (SSR)<br> <br> |
| Placebo Comparator: Placebo SSR<br>Placebo SSR | Radiation: Placebo SSR<br> <br> |
| Experimental: Oral Vitamin D3<br>Oral Vitamin D3 | Dietary Supplement: Oral Vitamin D3<br> <br> |
| Placebo Comparator: Placebo Oral Vitamin D3<br>Placebo Oral Vitamin D3 | Dietary Supplement: Placebo Oral Vitamin D3<br> <br> |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Vitamin D status | Circulating 25-hydroxy-vitamin D, 1,25-d OH(OH)D | Up to 20 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Physical performance 1 | Vertical Jump height (cm) and peak power output (watts) | Up to 20 months | 
| Physical performance 2 | Maximal dynamic lift strength (kg) | Up to 20 months | 
| Physical performance 3 | Multi-stage fitness test predicted VO2max (mL/kg/min) | Up to 20 months | 
| Hepatitis B antibody | Antibody produced in response to the presence of Hepatitis B antigen (e.g. Hepatitis B vaccine) | Up to 20 months | 
| Mucosal immunity | Secretory Immunoglobulin A levels | Up to 20 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Vitamin D deficiency, Simulated sunlight radiation, Oral vitamin D3