Clinical trial NCT04359524: Vitamin D Supplementation in Conscripts
Official title: Fitness and Health Characteristics in Conscripts With Supplementation of Vitamin D
Study type: INTERVENTIONAL
Overall status: COMPLETED
Phase: NA
Conditions: Vitamin D Deficiency
Military Activity
Lead sponsor: Tartu University Hospital
Sponsor class: OTHER
Collaborators: name: Estonian Defence Forces
name: University of Tartu
First posted: 2020-04-24
Enrollment: 63
Sex: MALE
Minimum age (years): 19
Maximum age (years): 27
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Intervention model description: Triple blinded randomized placebo-controlled study
Primary purpose: PREVENTION

Brief summary: 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: 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.

Eligibility criteria: 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

Primary outcomes:
measure: Prevalence of vitamin D deficence
timeFrame: 0, 2, 5 and 7 months of recruitment
Secondary outcomes:
Other outcomes:
measure: serum parathyroid hormone
timeFrame: 0, 2, 5 and 7 months of recruitment
measure: serum calcium
timeFrame: 0, 2, 5 and 7 months of recruitment
measure: serum ionized calcium
timeFrame: 0, 2, 5 and 7 months of recruitment
measure: Hand Grip Strength
timeFrame: 0, 2, 5 and 7 months of recruitment
measure: Testosterone
timeFrame: 0, 2, 5 and 7 months of recruitment
measure: Cortisol
timeFrame: 0, 2, 5 and 7 months of recruitment
Locations:
city: Võru
country: Estonia
facility: Kuperjanov Infantry Battalion, Estonian Defence Forces
state: Võrumaa
Study officials:
affiliation: University of Tartu
name: Helena Gapeyeva, MD, PhD
role: STUDY_DIRECTOR
References: