Chest
Volume 129, Issue 1, January 2006, Pages 39-49
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Original Research: Asthma
Protective Effect of Fish Oil Supplementation on Exercise-Induced Bronchoconstriction in Asthma

https://doi.org/10.1378/chest.129.1.39Get rights and content

Background

Previous research has demonstrated that fish oil supplementation has a protective effect on exercise-induced bronchoconstriction (EIB) in elite athletes, which may be attributed to its antiinflammatory properties. Since EIB in asthma involves proinflammatory mediator release, it is feasible that fish oil supplementation may reduce the severity of EIB in asthmatic subjects.

Study objectives

To determine the efficacy of fish oil supplementation on severity of EIB in subjects with asthma.

Design

Randomized, double-blind, crossover study.

Setting

Lung function and exercise testing in a university research laboratory.

Patients and measurements

Sixteen asthmatic patients with documented EIB entered the study on their normal diet and then received either fish oil capsules containing 3.2 g of eicosapentaenoic acid and 2.0 g of docohexaenoic acid (fish oil diet, n = 8) or placebo capsules (placebo diet, n = 8) daily for 3 weeks. At the beginning of the study (normal diet) and at the end of each treatment phase, the following pre-exercise and postexercise measures were assessed: (1) pulmonary function; (2) induced sputum differential cell count percentage and proinflammatory eicosanoid metabolite (leukotriene C4 [LTC4]-leukotriene E4 [LTE4] and prostaglandin D2 [PGD2]) and cytokine (interleukin [IL]-1β and tumor necrosis factor [TNF]-α) concentrations; and (3) eicosanoid metabolites leukotriene B4 (LTB4) and leukotriene B5 (LTB5) generation from activated polymorphonuclear leukocytes (PMNLs).

Results

On the normal and placebo diet, subjects exhibited EIB. However, the fish oil diet improved pulmonary function to below the diagnostic EIB threshold, with a concurrent reduction in bronchodilator use. Induced sputum differential cell count percentage and concentrations of LTC4-LTE4, PGD2, IL-1β, and TNF-α were significantly reduced before and following exercise on the fish oil diet compared to the normal and placebo diets. There was a significant reduction in LTB4 and a significant increase in LTB5 generation from activated PMNLs on the fish oil diet compared to the normal and placebo diets.

Conclusion

Our data suggest that fish oil supplementation may represent a potentially beneficial nonpharmacologic intervention for asthmatic subjects with EIB.

Section snippets

Subjects

Sixteen subjects (10 men and 6 women; mean age ± SD, 23 ± 1.6 years; body mass index, 23.05 ± 2.2 kg/m2 [normal diet]) with both physician-diagnosed asthma and documented EIB were recruited from a population of university students and the local community and indicated they were recreationally active. All subjects had clinically treated mild-to-moderate persistent asthma, with an FEV1 > 70% of predicted.14 A group of nonasthmatic (control) subjects was not included in the present study, as it

Subjects

Bronchodilator use (total number of doses/puffs) was significantly reduced (p < 0.05) during the last 2 weeks of the fish oil diet (45 puffs; 95% CI, 34 to 51 puffs) compared to the normal diet (61 puffs; 95% CI, 53 to 68 puffs) and placebo diet (65 puffs; 95% CI, 56 to 72 puffs). There was no significant difference (p > 0.05) in bronchodilator use between the normal and placebo diets. A 2 × 2 ANOVA that was used to test for the presence of carryover effects between diets indicated that none

Discussion

This study has demonstrated that a diet supplemented with fish oil ameliorates the severity of exercise-induced airway narrowing in subjects with mild-to-moderate persistent asthma. The fish oil diet improved pulmonary function to below the diagnostic EIB threshold of a 10% fall in postexercise FEV1, and reduced the fall in FEV1 at 15 min after exercise by approximately 64%. This improvement in postexercise pulmonary function on the fish oil diet was accompanied by a > 31% reduction in

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