Vitamin D Supplementation and Upper Respiratory Tract Infections in Adolescent Swimmers

Vitamin D Supplementation, Upper Respiratory Tract Infections, Immune and Physical Functions in Adolescent Swimmers

Background: The medical and economic burden of upper respiratory tract infections (URTIs) is extremely high, while prevention and treatment options are limited. Therefore, there is a constant need for new methods in order to significantly decrease such morbidity. Extensive evidence shows that vitamin D is associated with respiratory health, including in the prevention and treatment of URTIs. Competitive swimmers have a high prevalence of URTIs, and can serve as a model for research in this field.

The study hypothesis is that vitamin D supplementation to young swimmers with low vitamin D levels will reduce the frequency, length, and severity of URTIs and their accompanying functional impairment, while improving cellular immune function and physical function.

Methods: After screening 100 competitive adolescent swimmers to obtain ~60 with low serum levels of vitamin D, this study group will be randomized to receive either vitamin D supplementation (2000 IU/d) or placebo, given in a double blinded fashion for three months. Participants will fill a daily questionnaire regarding frequency, length and severity of URTIs symptoms and functional impairment. Blood will be drawn to evaluate changes in vitamin D status (25(OH)D) and immune function among study participants at the beginning of the study and after supplementation. Physical function on land and in water will also be assessed.

Expected results: Increase in serum 25(OH)D levels following supplementation will significantly decrease the frequency, length and severity of URTI's and their functional impairment, while enhancing the cellular immune system function and physical capacity.

Study Overview

• Status: Completed
• Conditions: Upper Respiratory Tract Infections
• Intervention / Treatment: Dietary supplement: vitamin D; Dietary supplement: placebo

• Study Type: Interventional
• Enrollment (Actual): 82
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Israel
  • Haifa, Israel
    • Maccabi Haifa Swimming Club
  • Herzlyia, Israel
    • Bnei Herzlyia Swimming Club
  • Hod Hasharon, Israel
    • Hod Hasharon Swimming Club
  • Maccabim, Israel
    • Maccabim-Reut Swimming Club

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 10 years to 16 years (Child, Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• members of swimming team
• training at least 15 hours/week
• low vitamin D plasma levels (<30 ng/ml)
• signed consent forms

Exclusion Criteria:

• chronic health conditions
• taking prescription medications
• taking diet supplementations

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: placebo	Dietary supplement: placebo; sweetened water
Active Comparator: vit D	Dietary supplement: vitamin D; 2000 IU/day of vitamin D3 as a once-daily dose

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
URI frequency	URI frequency will be measured in both groups, starting 4 weeks after initiating the suplementation. Analysis will also assess differences by sex or initial vitamin D levels, as well as by immune function changes.	3 months
URI duration	URI duration will be measured in both groups, starting 4 weeks after initiating the suplementation. Analysis will also assess differences by sex or initial vitamin D levels, as well as by immune function changes.	3 months
UTI severity	URI severity will be measured in both groups, starting 4 weeks after initiating the suplementation. Analysis will also assess differences by sex or initial vitamin D levels, as well as by immune function changes.	3 months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
plasma vitamin D levels		3 months
immune system function	T-cell receptor excision circles (TREC), T cell receptor repertoire, B-cell receptor excision circles (BREC). Comparison will be made with changes in vitamin D levels and with URI characteristics.	3 months
physical function	absence from school or training, land and swimming fitness tests. Comparison will be made with changes in vitamin D levels.	3 months

Collaborators and Investigators

• Sponsor: Sheba Medical Center
• Investigators: Principal Investigator: Gal Dubnov-Raz, MD MSc, Sheba Medical Center; Principal Investigator: Naama W Constantini, MD, Hadassah Medical Organziation; Principal Investigator: Avner Cohen, MD, Clalit Health Services; Principal Investigator: Raz Somech, MD PhD, Sheba Medical Center

Publications and helpful links

General Publications

• Dubnov-Raz G, Rinat B, Hemila H, Choleva L, Cohen AH, Constantini NW. Vitamin D supplementation and upper respiratory tract infections in adolescent swimmers: a randomized controlled trial. Pediatr Exerc Sci. 2015 Feb;27(1):113-9. doi: 10.1123/pes.2014-0030. Epub 2014 Jul 15.

Study record dates

Study Major Dates

• Study Start: October 1, 2010
• Primary Completion (Actual): March 1, 2011
• Study Completion (Actual): March 1, 2011

Study Registration Dates

• First Submitted: October 5, 2010
• First Submitted That Met QC Criteria: October 5, 2010
• First Posted (Estimate): October 6, 2010

Study Record Updates

• Last Update Posted (Estimate): March 26, 2012
• Last Update Submitted That Met QC Criteria: March 22, 2012
• Last Verified: March 1, 2012

More Information

Terms related to this study

• Keywords: children; infections; immune system; vitamin D; sport
• Additional Relevant MeSH Terms: Pathologic Processes; Respiratory Tract Diseases; Disease Attributes; Infections; Communicable Diseases; Respiratory Tract Infections; Physiological Effects of Drugs; Micronutrients; Vitamins; Bone Density Conservation Agents; Vitamin D
• Other Study ID Numbers: SHEBA-10-7762-GDR-CTIL