Respiratory Health: Studies

Reduced Asthma Symptoms With N-3 Fatty Acid Ingestion

Am J Clin Nutr. 1997 Apr;65(4):1011-7

Broughton KS, Johnson CS, Pace BK, Liebman M, Kleppinger KM.

Asthma may respond to dietary modification, thereby reducing the need for pharmacologic agents. This study determined the effectiveness of n-3 polyunsaturated fatty acid (PUFA) ingestion in ameliorating methacholine-induced respiratory distress in an asthmatic population. The ability of urinary leukotriene excretion to predict efficacy of n-3 PUFA ingestion was assessed. After n-3 PUFAs in ratios to n-6 PUFAs of 0.1:1 and 0.5:1 were ingested sequentially for 1 mo each; patient respiratory indexes were assessed after each treatment. Forced vital capacity (FVC), forced expiratory volume for 1 s (FEV1), peak expiratory flow (PEF), and forced expiratory flow 25-75% (FEF 25-75) were measured along with weekly 24-h urinary leukotriene concentrations. With low n-3 PUFA ingestion, methacholine-induced respiratory distress increased. With high n-3 PUFA ingestion, alterations in urinary 5-series leukotriene excretion predicted treatment efficacy. Elevated n-3 PUFA ingestion resulted in a positive methacholine bronchoprovocation dose change in > 40% of the test subjects(responders). The provocative dose to cause a 20% reduction (PD20) in FEV1, FVC, PEF, and FEF25-75 values could not be calculated because of a lack of significant respiratory reduction. Conversely, elevated n-3 PUFA ingestion caused some of the patients (nonresponders) to further lose respiratory capacity. Five-series leukotriene excretion with high n-3 PUFA ingestion was significantly greater for responders than for nonresponders. A urinary ratio of 4-series to 5-series leukotrienes < 1, induced by n-3 PUFA ingestion, may predict respiratory benefit.

 

Fish Oil For Many Types Of Asthma

Respiration. 1998;65(4):265-9.

Villani F, Comazzi R, De Maria P, Galimberti M.

Dietary supplementation with omega-3 essential fatty acids results in the production of uniqe 5-lipoxygenase and cyclooxygenase products which are biologically less active and may inhibit the production, or actions, of the eicosanoids produced when arachidonic acid is the substrate for 5-lipoxygenase and cyclooxygenase, rather than omega-3 essential fatty acids. Since airway inflammation may play a central role in the pathophysiology of asthma, we studied the effect of omega-3 essential fatty acids on bronchial responsiveness in 7 atopic patients suffering from seasonal asthma due to airborne allergens, and positive to intracutaneous skin reaction to two or more allergens. Bronchial responsiveness to ultrasonically nebulized distilled water (UNDW) was determined 30 days from the initial ingestion of 3 g/day of omega-3 essential fatty acids and 30 days after stopping dietary supplementation. Flow volume curves and Raw were recorded before the provocation test, at the end of inhalation, and at 10-, 20-, 30- and 60-min intervals. The maximum fall in forced expiratory volume in 1s (FEV1) and the maximum increase in airway resistance (Raw) were chosen as the main outcome parameters. After 30 days of dietary supplementation, bronchial responsiveness to UNDW was significantly improved (in fact maximum fall in FEV1 was -11% vs. -28% before treatment, and maximum increase in Raw was +37% vs. +265% before treatment). The challenge test repeated 30 days after stopping dietary supplementation was the same as that recorded before treatment. The present data strongly suggest the hypothesis that dietary supplementation with omega-3 essential fatty acids could decrease bronchial hyperreactivity in atopic patients.

 

Protective effect of fish oil supplementation on exercise-induced bronchoconstriction in asthma.

Chest. 2006 Jan;129(1):39-49.

Mickleborough TD, Lindley MR, Ionescu AA, Fly AD.

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]-1beta and tumor necrosis factor [TNF]-alpha) concentrations; and (3) eicosanoid metabolites leukotriene B4 (LTB4) and leukotriene B5 (LTB(5)) 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-1beta, and TNF-alpha 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.

 

Dietary polyunsaturated fatty acids in asthma- and exercise-induced bronchoconstriction.

Eur J Clin Nutr. 2005 Dec;59(12):1335-46.

Mickleborough TD, Rundell KW.

Despite progress that has been made in the treatment of asthma, the prevalence and burden of this disease has continued to increase. While pharmacological treatment of asthma is usually highly effective, medications may have significant side effects or exhibit tachyphylaxis. Alternative therapies for treatment that reduce the dose requirements of pharmacological interventions would be beneficial, and could potentially reduce the public health burden of this disease. Ecological and temporal data suggest that dietary factors may have a role in recent increases in the prevalence of asthma. A possible contributing factor to the increased incidence of asthma in Western societies may be the consumption of a proinflammatory diet. In the typical Western diet, 20- to 25-fold more omega (n)-6 polyunsaturated fatty acids (PUFA) than n-3 PUFA are consumed, which promotes the release of proinflammatory arachidonic acid metabolites (leukotrienes and prostanoids). This review will analyze the evidence for the health effects of n-3 PUFA in asthma- and exercise-induced bronchoconstriction (EIB). While clinical data evaluating the effect of omega-3 fatty acid supplementation in asthma has been equivocal, it has recently been shown that fish oil supplementation, rich in n-3 PUFA, reduces airway narrowing, medication use, and proinflammatory mediator generation in nonatopic elite athletes with EIB. These findings are provocative and suggest that dietary fish oil supplementation may be a viable treatment modality and/or adjunct therapy in asthma and EIB.