Effect of Dietary Supplements With Fish Oil on Mannitol-induced Airway Sensitivity & Inflammation in Persons With Asthma

Asthma Clinical Trial

Official title: The Effect of Dietary Supplementation With Encapsulated Fish Oil on Mannitol-induced Airway Sensitivity and Inflammation in Persons With Asthma

Status Completed

Clinical Trial Summary

We wish to investigate the effects of 3 weeks of orally administered fish oil supplements on the airway sensitivity (provoking dose to cause a 15% fall in FEV1, PD15) to inhaled mannitol (AridolTM). Mannitol, an osmotic stimulus has been demonstrated as a useful model for exercise-induced asthma. We also wish to investigate if there is any associated improvement associated with selected markers of airway inflammation that can be measured in the sputum, blood, urine and exhaled breath condensate. Oral fish oil supplements have recently been demonstrated to be effective inhibitors of exercise-induced asthma, in association with an inhibition of markers of inflammation, over a 3 week treatment period. This finding has important implications in the treatment of asthma as this is a faster and more effective improvement than what is seen with inhaled corticosteroids on exercise-induced asthma. This observation requires validation and further investigation. We wish to study this in two patient groups; (a) steroid naïve asthmatics taking beta2 agonist when required and (b) asthmatics taking regular inhaled corticosteroids < 1000 mcg/day.

Clinical Trial Description

Asthma is a chronic inflammatory disorder of the airways characterized by recurrent episodes of dyspnea, wheeze and chest tightness and is associated with variable airway obstruction. Exercise-induced bronchoconstriction (EIB) is a feature specific to asthma. Exercise testing protocols have been developed to identify the presence of asthma as well as to assess asthma therapy. Airway narrowing following exercise in persons with asthma is thought to result from dry air hyperpnoea-induced dehydration of the airway surface, leading to the release of mediators from inflammatory cells residing in the airway. Regular treatment with inhaled corticosteroids inhibits the airway response to exercise by decreasing the number of inflammatory cells and thus the source of bronchoconstricting mediators. Therefore, a decrease in the source of mediator may be the reason for this eventual inhibition of the airway response to exercise.

It has recently been demonstrated that fish oil supplementation in capsule form, taken daily over three weeks, provides significant protection against EIB. This protection appears to be of equal or greater efficacy than inhaled corticosteroids treatment over a similar period. This may have positive implications in the treatment of asthma as inhaled corticosteroids are known to have some unwanted side effects. Fish oil supplementation in the high doses given in previous studies have not demonstrated any side effects and may lead to an alternative treatment, or a decrease in the dose of inhaled steroids required in the treatment of asthma.

A new bronchial provocation test using inhaled mannitol, derived from the mechanism of EIB, has been recently developed and is now registered in Australia and the European Union. Mannitol causes airway narrowing in a similar manner to exercise in persons with asthma and is effective in identifying responsiveness to inhaled corticosteroids. We wish to use inhaled mannitol as a model for EIB in an effort to further investigate the use of fish oil supplementation in the treatment of asthma. Our hypothesis is that daily orally administered encapsulated fish oil will attenuate the airway response to mannitol over a 3-week treatment period. We also wish to measure associated markers of inflammation in the blood, urine, sputum and exhaled condensate as well as monitor clinical outcomes such as symptoms and daily beta2 agonist use. ;

Study Design

Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Caregiver, Investigator), Primary Purpose: Treatment

Related Conditions & MeSH terms

• Asthma
• Inflammation

• NCT number: NCT00526357
• Study type: Interventional
• Source: Firestone Institute for Respiratory Health
• Status: Completed
• Phase: Phase 2
• Start date: August 2007
• Completion date: March 2012