Sunlight Exposures Effect on Serum Vitamin D Levels

Study Overview
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Brief Summary
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When people eat a meal, some, but not all of the calcium in that meal is absorbed, that is, moved into the bloodstream. When the skin is exposed to sunlight during summer months, Vitamin D is made there and then modified into more active forms by the liver and kidneys. These more active forms of Vitamin D improve calcium absorption. Many adults living in the U.S. have little or no sun exposure and are low in Vitamin D. We know that specific wavelengths of sunlight called Ultraviolet-B cause Vitamin D to be made in the skin.

Detailed Description
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At the beginning of the study we will measure your height, weight, skin color, and draw blood to measure your blood levels of Vitamin D and 25-hydroxyvitamin D. Each subject will wear a swimming suit and be exposed to sunlight for 30 minutes total (15 minutes lying on back, 15 minutes lying on stomach).We will draw blood for Vitamin D and 25-hydroxyvitamin D on days 1,2,3,5, and 7 after sunlight exposure. There will be six blood draws for a total of 102 cc of blood drawn (about 3 ½ teaspoons drawn each time).

Official Title
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Sunlight Exposures Effect on Serum Vitamin D Levels

Conditions
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Vitamin D Deficiency

Intervention / Treatment
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* Behavioral: Sun Exposure


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: healthy males or females ages19-50 with light skin (self-assessed as Fitzpatrick skin type I-III) with minimal sun exposure and exogenous sources of vitamin D. Exclusion Criteria: less than 16 oz milk per day, less than 10 hours of sun per week, no Vitamin D supplements, no anticonvulsants, no barbiturates, no steroids, no meds that increase photosensitivity, no granulomatous disease, no liver or kidney disease, no history of skin cancer, and BMI less than 30.

Ages Eligible for Study
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Minimum Age: 19 Years
Maximum Age: 50 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
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br>All subjects in this study will be in the active arm | Behavioral: Sun Exposure<br>* Each subject will wear a swimming suit and be exposed to sunlight for 30 minutes total (15 minutes lying on back, 15 minutes lying on stomach).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The goal of this study is to correlate vitamin D response and 25(OH)D response to sun exposure with most of the body (90 %) exposed to 0.25 hour of July sunlight at 41.2º N latitude and at approximately 1-2 pm in the afternoon. |  | 1 week | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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sunlight, UVB, Vitamin D