Vitamin C & Exercise Induced Bronchoconstriction (EIB)

Study Overview
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Brief Summary
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The purpose of this research is to assess the association between diet and pulmonary function during standardized EIB testing. Determine the effect of Vitamin C supplementation on airway inflammatory markers and bronchoconstriction after a standardized EIB test compared to usual diet and placebo control.

Detailed Description
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This study will use a double-blind, randomized, cross-over design with subjects serving as their own controls. This study will be conducted over a consecutive five-week period. All subjects will be asked to discontinue taking their short- and long-acting beta-agonist medication 12 and 24 hours respectively prior to data collection. Also, all subjects will be asked to refrain from caffeine, physical activity, and NSAID use 24 hours prior to testing. In addition all subjects will be asked to abstain from taking any vitamin supplement during the course of the study.

Official Title
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Vitamin C Supplementation to Improve EIB in College Student-Athletes

Conditions
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Exercise-induced Bronchospasm

Intervention / Treatment
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* Dietary Supplement: Vitamin C
* Other: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Student or student-athlete who has tested positive for EIB Able to communicate in English Exclusion Criteria: Forced expiratory volume in 1 second (FEV1) < 70% of predicted, cardiac history, Current respiratory infection > 10 pack year history of smoking Pregnancy.

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Vitamin C<br>Participants will ingest 3 (500 mg) capsules of Vitamin C each day for 2 weeks. | Dietary Supplement: Vitamin C<br>* Taken as 3 500mg capsules.<br>|
| Active Comparator: Placebo<br>Participants will ingest a matched capsule for size and color to the Vitamin C supplement. | Other: Placebo<br>* Taken as 3 500mg capsules.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in airway inflammatory biomarkers | Urinary concentrations of cysteine leukotrienes (LTC4-LTE4), prostaglandin (9α,11β-PGF2), and creatinine will be measured. | Change from Baseline to End of Week 5 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change in quality of life: asthma quality of life questionnaire (AQLQ) | Asthma specific quality of life will be measured by the validated asthma quality of life questionnaire (AQLQ). The AQLQ includes 32 separate responses within 4 domains: activity limitation (11 items), symptoms (12 items), emotional function (5 items), and environmental stimuli (4 items). Each response option is based on a 7-point scale, where 1 represents maximal impairment and 7 indicates no impairment. Scores for the four domains and overall score are computed as averages of the item scores. The minimal important difference for overall and each domain, has been determined to be a change in score of 0.5 per item. | Change from Baseline to End of Week 5 | 
| Dietary Intake Questionnaire | Baseline dietary intake will be assessed by the National Cancer Institute's Diet Health Questionnaire II (DHQ II). It consists of 134 food items and 8 dietary supplement questions. It calculates the Healthy Eating Index (HEI) that is a measure of diet quality. Scores range from 0 to 100. The higher the score the healthier the diet. | Change from Baseline to End of Week 5 | 
| Cardiorespiratory Fitness | Cardiorespiratory fitness will be assessed during the EIB test by an integrated metabolic measurement system that will be used for measurement of oxygen consumption. The metabolic cart will be set to produce a 15-second average of the data collected during gas analyses for all tests. | Baseline | 
| Pulmonary function testing | The outcome will measure the change in the first second of forced expiration (FEV1). | Change from Baseline to End of Week 5 |