Immune and Metabolic Effects of Vitamin D Supplementation in Healthy Humans

Study Overview
=================
Brief Summary
-----------------
In this placebo controlled study the investigators aim to investigate the effect of a 3 month vitamin D supplementation on parameters of the immune, endocrine and metabolic system in healthy women and men. Vitamin D. In a pilot study the investigators showed an increase of certain immune cells, which regulate immunotolerance, the investigators therefore try to confirm these results with a placebo group. Furthermore the investigators assess the effect of vitamin D on the glucose metabolism and hormone levels.

Detailed Description
-----------------
This is a randomized double-blind placebo controlled trial, with the aim to investigate the effect of a Vitamin D supplementation on parameters of the immune, endocrine and metabolic system in healthy humans without diabetes and obesity. The primary aim is to assess the effect of vitamin D supplementation of the number and function of peripheral regulatory T-cells (Tregs). The investigators will measure the Tregs at baseline and monthly for 3 months. Furthermore the investigators assess additional immune cells from the adaptive immunosystem. Furthermore the investigators will perform a standard mixed meal tolerance test at baseline and 3 months following the supplementation in order to assess the insulin secretion in vivo.

Official Title
-----------------
Placebo Controlled Study to Assess the Effects of Vitamin D Supplementation on Parameters of the Immune, Endocrine and Metabolic System in Healthy Women and Men.

Conditions
-----------------
Healthy Humans

Intervention / Treatment
-----------------
* Drug: Cholecalciferol
* Drug: Placebo


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Age >= 10 years healthy subjects without chronic disease Exclusion Criteria: Hypercalcemia >2,65 mmol/L pregnancy and lactation period acute infections chronic disease requiring treatment

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

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


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Cholecalciferol<br> | Drug: Cholecalciferol<br>* monthly dose of 140.000 IU of cholecalciferol orally, 3 times.<br>* Other names: Oleovit D3;|
| Placebo Comparator: Placebo<br> | Drug: Placebo<br>* Matching Placebo<br>* Other names: Almondoil;|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Increase and function of peripheral regulatory T-cells | The level and function of the regulatory T-cells will be compared between the two groups. | 3 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| immunophenotyping | The effect of vitamin D on circulating immune cells and cytokine secretion will be measured at basal and after 3 months. | 3 months | 
| Renin and aldosterone concentrations | serum renin and aldosterone levels will be measured basal and after 3 months. | 3 months | 
| Insulin secretion | Insulin secretion assessed with a mixed meal tolerance test will be performed basal and after 3 months | 3 months | 
| calcium levels | serum calcium levels will be measured basal and monthly for 3 months. | 3 months | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Vitamin D Deficiency, Autoimmune disease, Diabetes