Soy Supplements Deemed Ineffective in Asthma Care

Clinical trial refutes prior notion that the nutrient might boost lung function

WEDNESDAY, May 27, 2015 (HealthDay News) -- Despite hints from prior research that soy supplements might help asthma patients breathe easier, a new study indicates the nutrient has no beneficial effect on lung function. The findings were published in the May 26 issue of the Journal of the American Medical Association.

Lewis Smith, M.D., of the Northwestern University Feinberg School of Medicine in Chicago, and colleagues studied the effects of soy in 386 people age 12 and older with poorly controlled asthma. All of them were taking medications to treat their asthma, but none were consuming soy regularly before enrolling in the study. Half of the participants took a soy isoflavone supplement twice daily for six months, while the other half took a placebo.

The researchers found that mean plasma genistein level increased in participants receiving the supplement, but appeared to have no impact on lung function, symptoms, or measures of inflammation. "These findings suggest that this supplement should not be used for patients with poorly controlled asthma," the authors conclude.

"This study highlights why it is so important to perform well-designed, placebo-controlled studies when associations are reported between specific nutrients and disease outcomes," Smith said in a university news release.

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