Previous studies have suggested that soy intake leads to decreased asthma severity. It was disapproved by the recent findings by the study conducted by the Northwestern Medical medicine and the American Lung Association Asthma Clinical Research Network, published Tuesday in the Journal of the American Medical Association (JAMA).
"You are what you eat, but that's a whole constellation of foods, not just a single food or a single component of a food," said first author Lewis Smith, professor of medicine at Northwestern University Feinberg School of Medicine.
The study examined the effects of soy in 386 adults and children aged 12 or older with poorly controlled asthma. All were taking medicine to treat their asthma but none were consuming soy. In the randomized study, half of the participants took a soy isoflavone supplement twice daily for six months, and the other half took a placebo.
"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.