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Completed

NCT Number: NCT04359524

Vitamin D Supplementation in Conscripts

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

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Key information

Conditions

Vitamin D Deficiency Avitaminosis Deficiency Diseases Malnutrition Military Activity Nutrition Disorders Nutritional and Metabolic Diseases

Age range

19 year–27 year

Sex eligibility

Male

Study type

Interventional

Phase

Not applicable

Primary location

Kuperjanov Infantry Battalion, Estonian Defence Forces

Võru, Võrumaa, 50400, Estonia

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Vitamin D3 (1200 IU/30µg)

Dietary Supplement

Placebo

Dietary Supplement

Placebo oil capsule

Primary outcomes

  1. Prevalence of vitamin D deficence

    Time frame: 0, 2, 5 and 7 months of recruitment

    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.

Other outcomes

  1. serum parathyroid hormone

    Time frame: 0, 2, 5 and 7 months of recruitment

    serum parathyroid hormone concentration (pmol/l)

  2. serum calcium

    Time frame: 0, 2, 5 and 7 months of recruitment

    serum calcium (Ca) concentration (mmol/l)

  3. serum ionized calcium

    Time frame: 0, 2, 5 and 7 months of recruitment

    serum ionized calcium (Ca-i) concentration (mmol/l)

  4. Hand Grip Strength

    Time frame: 0, 2, 5 and 7 months of recruitment

    Hand grip strength is determined by isometric contraction while standing, upper limb away from the body, using a hand dynamometer (Lafayette Instrument Co., USA).

  5. Testosterone

    Time frame: 0, 2, 5 and 7 months of recruitment

    Serum testosterone concentration (nmol/l)

  6. Cortisol

    Time frame: 0, 2, 5 and 7 months of recruitment

    Serum cortisol concentration (nmol/l)

Sponsors and collaborators

Lead sponsor

Leho Rips

Other

Collaborators

  • Estonian Defence Forces
  • University of Tartu

Registry information

Official study title

Fitness and Health Characteristics in Conscripts With Supplementation of Vitamin D

Important dates

Study start
2016
Primary completion
2017
Study completion
2017
First posted
Apr 24, 2020
Registry last updated
Sep 17, 2021

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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