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

 -  Male or female (medically or surgically postmenopausal or practicing an accepted form
 of barrier or hormonal contraception) subjects age 18-55.

 -  Stable, mild atopic asthma with forced expiratory volume in one second (FEV1) greater
 than 70% of predicted for age and height, and not requiring any medical treatment
 other than short acting inhaled beta2-agonists as required or for those on steroids,
 taking < 1000 mcg of inhaled corticosteroid per day.

 -  No recent or significant history of cigarette smoking (no smoking within six months
 prior to entry into the study; less than 10 pack-years cumulative history of cigarette
 smoking).

 -  Signed written informed consent to participate in the study; ability to return to the
 clinic for repeated visits.

 -  No history of asthma exacerbations or acute intercurrent respiratory illness (viral
 respiratory syndrome, bronchitis, pneumonia) for a four week period preceding entry
 into the screening phase of the study.

 -  Subjects who take inhales steroids regularly must demonstrate reproducibility to
 inhaled mannitol (PD15<1.0 doubling doses) during a 2 week run-in period.

 -  A PD15 to the mannitol challenge < 315mg

 Exclusion Criteria:

 -  Significant gastrointestinal (including hepatic), hematological, cardiovascular,
 cerebrovascular, metabolic such as including type II diabetes or other body system
 disorder.

 -  Regular consumption of fish consisting more than 1 meal of fish per week or regular
 fish oil supplements during the trial and for at least 2 weeks prior to the first
 study visit.

 -  Subjects who have taken oral corticosteroids or a leukotriene receptor antagonist in 4
 weeks prior to entry into the study.

 -  Psychosis, alcoholism, active substance abuse, or any personality disorder, which
 would make compliance with this protocol problematic.

 -  Pregnant or nursing females.

 -  Any other medical or social condition which, in the opinion of the investigator, could
 confound the interpretation of the data derived from this study.

 -  Subjects taking >1000 mcg of inhaled steroids daily in those subjects taking inhaled
 steroids.

 -  Subjects requiring regular anti-histamines for allergies.

 -  Subjects who have allergy to fish or any other ingredient in the study products.

 -  Subjects using anti-coagulants (warfarin, heparin)

 -  Subjects who have surgery planned over the course of the trial.

 -  Subjects who use medications to lower LDL cholesterol levels

 -  Subjects using non-steroidal anti-inflammatory medications (e.g., aspirin, ibuprofen)