American Lung Association Asthma Clinical Research Centers Present Results on Whether Soy Improves Asthma

(May 20, 2013)

Washington, D.C. — Asthma has increased in prevalence and severity over the last several decades for unknown reasons.  Researchers suggest that a person’s diet may impact asthma and that specific foods, such as soy, are likely to improve asthma.  However, the latest study from the American Lung Association Asthma Clinical Research Centers (ACRC), found that ingesting a major component of soy in pill form had no effect on asthma compared to a group taking placebo. 

The initial results of the Study of Soy Isoflavones in Asthma (SOYA) were recently reported at the American Thoracic Society Annual Meeting. ACRC researchers randomly assigned 386 inadequately controlled asthma patients, 12 years of age or older, who were taking either inhaled corticosteroids or leukotriene modifiers, to treatment with either a soy isoflavone supplement or placebo for six months. 

Results of the SOYA trial indicated that soy had no effect on lung function.  Furthermore, researchers found no differences in asthma symptoms, quality of life, inflammatory markers or adverse effects between the two treatment groups. 

“Preliminary findings from our group suggested that soy isoflavone supplements might have improved asthma.” said Lewis J. Smith, MD, of the ACRC at Northwestern University and lead Investigator of the SOYA study. “Unfortunately, we did not see improvement in this larger trial.  It is very hard to control for the intake of other nutrients, which may have interacted or negated soy’s true effect on asthma.”  

Archer Daniels Midland Company provided soy isoflavone powder for the study, which was funded by the American Lung Association and the National Heart, Lung and Blood Institute, a component of the National Institutes of Health. 

The ACRC Network is an American Lung Association sponsored research program that conducts large scale clinical trials with the mission of advancing the care and treatment of people with asthma. The network, with a central data coordinating center and 18 clinical centers located across the country, is the largest nonprofit network of its kind. By placing numerous clinical centers nationwide, the ACRC Network is able to enroll large numbers of patients for clinical trials, thus ensuring relevant research findings can be interpreted with the highest level of scientific authority.



About the American Lung Association
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