Vitamin D Supplementation in Conscripts

Study Overview
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Brief Summary
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A longitudinal, triple-blinded, randomized, placebo-controlled trial, with a 7-month follow-up period is conducted between October 2016 to April 2017.

Detailed Description
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Body mass (kg) and height (cm) is measured by the same person at the medical center using standardized equipment and the body mass index (BMI) is calculated in kg/m2. Computed randomization is used to divide conscripts into two groups; either the intervention group or the control group. Both types of capsules are administered once per day in the morning before breakfast for 7 months. Standardized coded packages (3 per conscript) and capsules (100 per package) are manufactured on a special order by Innopharma A/S (Denmark). No commercial sponsoring is involved. The key of the package code is stored in the computer database until unblinding of the results. Laboratory measurements Serum samples for clinical chemistry analysis are collected into serum clot activator tubes. Calcium measurements are performed using spectrophotometry method. Ionized calcium measurements are performed using ion selective electrodes. The direct chemiluminescent immunoassay method is used for measurement of PTH. 25(OH)D is measured using direct chemiluminescent immunoassay method. Power calculation The primary variable of the study is the level of 25 (OH)D in the serum. In the power analysis a difference of 20 nmol/L between the intervention and the control group is considered to be meaningful to detect. If the SD would be 25 nmol/L, then 26 participants would be needed in each group to reach a power of 80%. Statistical analysis The distribution of blood serum values in the study groups is described by means and standard deviations (SD). Differences in mean values of the variables of interest between the groups are evaluated using Welch t-test. The within group comparisons over time are performed using paired t-test with Bonferroni correction. Distributions of categorical variables are described by absolute numbers and percentages and compared between groups using the Fisher exact test. Statistical significance is set at the 0.05 probability level.

Official Title
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Fitness and Health Characteristics in Conscripts With Supplementation of Vitamin D

Conditions
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Vitamin D Deficiency, Military Activity

Intervention / Treatment
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* Dietary Supplement: Vitamin D3 (1200 IU/30µg)
* Dietary Supplement: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: participating in military service at the Estonian Defence Forces voluntarity to participate in the study Exclusion Criteria: inability to continue military service for any reason, during the 7 month follow-up period

Ages Eligible for Study
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Minimum Age: 19 Years
Maximum Age: 27 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
Interventional Model Description: Triple blinded randomized placebo-controlled study
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Intervention<br>Received vitamin D3 capsules (1200 IU/30µg). | Dietary Supplement: Vitamin D3 (1200 IU/30µg)<br> <br> |
| Placebo Comparator: Control<br>Received placebo (oil capsules). | Dietary Supplement: Placebo<br>* Placebo oil capsule<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Prevalence of vitamin D deficence | Prevalence of vitamin D deficence as measured serum vitamin D 25(OH)D concentration. Vitamin D was considered as sufficient if the se-rum 25(OH)D concentration was ≥75 nmol/L, insufficient if <75 nmol/L, and deficient if <50 nmol/L. | 0, 2, 5 and 7 months of recruitment |