Diet, or a rearrangement of dietary components, can modify disease, says Indiana University exercise physiologist Timothy Mickleborough.

Nine years ago – before all the buzz about omega-3 fatty acid supplements began -- Mickleborough and research colleagues at IU and elsewhere began studying the impact of dietary salts, fish oil, and antioxidants on EIA, also called exercise-induced bronchoconstriction. They found that a low-salt diet can reduce airway inflammation and the severity of EIA, and more recently, that fish oil and ascorbic acid (vitamin C) supplementation can also reduce airway inflammation and EIA symptoms to below the threshold used to diagnose the condition.

Exercise-induced asthma, with its uncomfortable coughing and wheezing, occurs when vigorous exercise triggers a narrowing of the airway. It can discourage people from participating in sports and other physical activity as well as hamper workouts, races, and contests for competitive athletes. Asthma medications can be extremely effective, Mickleborough notes, but they also have real and potential side effects, such as toxicity and reduced effectiveness from long-term use. Some medications are banned in international competition.

“Alternative therapies for exercise-induced asthma, or therapies that reduce the dose requirements of traditional medications, would be a benefit to the asthmatics and potentially reduce the public health burden of this disease,” Mickleborough says.

Research findings by Mickleborough and his colleagues have been published in the journals Chest (see http://newsinfo.iu.edu/news/page/normal/2751.html ), Journal of Sports Sciences , Medicine & Science in Sports & Exercise (see http://newsinfo.iu.edu/news/page/normal/2175.html ), and the American Journal of Respiratory and Critical Care Medicine . Besides ample coverage in the mass media, Mickleborough is regularly asked to contribute review articles about the topic to academic journals.

Why the interest? Asthma prevalence has increased dramatically in many countries over recent decades, and Mickleborough points out, in the past two decades, evidence on the relation between diet and asthma has increased substantially as well. In some recent studies, Mickleborough and his colleagues have found that

• the post-exercise lung function of adults with mild-to-moderate persistent asthma improved by about 64 percent and their use of bronchodilators decreased by 31 percent when they consumed a diet supplemented with fish oil, rich in omega-3 polyunsaturated fatty acids (n-3 PUFA), for three weeks. IU co-authors of the report include Martin Lindley, research scientist in the IUB Department of Kinesiology and Alyce Fly, associate professor in the IUB Department of Applied Health Science.
• participants on a high-salt diet showed a dramatic decline of 27.4 percent in measured lung function after physical activity, compared to just 7.9 percent for participants on the low-salt diet. Mickleborough attributes this to a combination of factors caused by the high-salt diet, including high blood pressure and increased blood volume, which can cause pulmonary edema leading to airway obstruction. Co-authors of this study include Lindley and Shahla Ray, visiting lecturer, in the IUB Department of Applied Health Science.
• post-exercise lung function dropped by an average 6.4 percent for participants receiving ascorbic acid supplementation, compared to drops of 14.3 percent and 12.9 percent for participants on a normal diet or receiving a placebo respectively. Sandy Tecklenburg, a doctoral student working with Mickleborough in the Department of Kinesiology, completed this study.

Mickleborough and co-researchers currently have a $2 million grant application under review at the National Institute of Health to further clarify the role of omega-3 fatty acids in asthma. In addition, Mickleborough is collaborating with Gregory Montgomery at the IU School of Medicine (pediatric pulmonology) on issues related to childhood obesity and asthma.