New study confirms prior findings; omega-3s exert anti-inflammatory effect
by Craig Weatherby
In the condition called “exercise-induced asthma” (EIA), vigorous exercise triggers an acute narrowing of the airway, making breathing difficult. Some 80 percent of people with asthma suffer from EIA, which also afflicts an estimated 10 percent or more of elite athletes and about 10 percent of people without asthma.
Given its alarming effects, fear of EIA can keep adults and children alike from exercising or participating in sports or other healthful physical activities.
A team led by Timothy D. Mickleborough, Ph.D., Assistant Professor of Kinesiology at Indiana University, tested the effects of supplemental fish oil on the post-exercise lung function of participating adults with mild-to-moderate persistent asthma.
What the study showed
This randomized, double-blind cross-over study involved 16 recreationally active people with mild-to-moderate persistent asthma who required daily medications to control their symptoms.
For three weeks, one group took fish oil capsules, while the other took placebo capsules containing olive oil. To isolate any benefit occurring from either oil, all participants stopped their medication during the course of the study.
At the end of the study period, average lung function within the fish oil test group improved by about 64 percent, while their use of emergency inhalers decreased by 31 percent. The placebo (olive oil) group experienced no benefit.
The test group's fish oil regimen delivered 3.2 grams of omega-3 EPA and 2 grams of omega-3 DHA, daily: the amount of EPA and DHA found in about 17 typical fish oil capsules, or two-to-four 6 oz servings of Alaskan sockeye salmon.
It is quite possible that lower doses would impart substantial, if not equal benefit, especially if sustained over a longer period. This is because it takes time for the fatty acid composition of our cells—the operative anti-inflammatory mechanism—to change.
Omega-6 overload called a likely culprit
One of the IU team’s key findings was that levels of pro-inflammatory cells and markers responsible for airway inflammation and subsequent obstruction were reduced in the EIA subjects taking supplemental fish oil.
The omega-6/omega-3 fatty acid imbalance typical of Western populations’ diets may account for the benefits of taking omega-3s.
As Dr. Mickleborough noted in his paper: “A possible contributing factor to the increased incidence of asthma in Western societies may be the consumption of a pro-inflammatory diet. In the typical Western diet, 20- to 25-fold more… [omega-6 polyunsaturated fatty acids]… than… [omega-3s] are consumed, which promotes the release of pro-inflammatory arachidonic acid metabolites (leukotrienes and prostanoids).” [Omega-6] PUFA are found in such items as sunflower, safflower and corn oils.…” And, we should add, relatively pro-inflammatory omega-6 fatty acids are common, abundant, and dominant in packaged and frozen foods.
- Indiana University press release. “Fish oil shown to reduce airway inflammation caused by exercise-induced asthma”. Accessed online January 9, 2005 at http://newsinfo.iu.edu/news/page/normal/2751.html.
- Mickleborough TD, Lindley MR, Ionescu AA, Fly AD. Protective Effect of Fish Oil Supplementation on Exercise-Induced Bronchoconstriction in Asthma. Chest. 2006;129:39-49.
- Mickleborough TD, Rundell KW. Dietary polyunsaturated fatty acids in asthma- and exercise-induced bronchoconstriction. Eur J Clin Nutr. 2005 Dec;59(12):1335-46.
- Mickleborough TD. Dietary omega-3 polyunsaturated fatty acid supplementation and airway hyperresponsiveness in asthma. J Asthma. 2005 Jun;42(5):305-14. Review.
- Mickleborough TD, Ionescu AA, Rundell KW. Omega-3 Fatty acids and airway hyperresponsiveness in asthma. J Altern Complement Med. 2004 Dec;10(6):1067-75. Review.
- Mickleborough TD, Murray RL, Ionescu AA, Lindley MR. Fish oil supplementation reduces severity of exercise-induced bronchoconstriction in elite athletes. Am J Respir Crit Care Med. 2003 Nov 15;168(10):1181-9. Epub 2003 Aug 6.