Dietary Supplementation With Soy Isoflavones in Asthma
Status:
Completed
Trial end date:
2007-04-01
Target enrollment:
Participant gender:
Summary
An epidemiologic study of patients with asthma has shown that increased intake of soy
isoflavones correlates with less severe asthma. In experimental animals, treatment with the
soy isoflavone genistein reduces airways inflammation and hyper-responsiveness. In vitro
studies performed by us have shows that genistein reduces release of inflammatory compounds
by human blood eosinophils. The purpose of this pilot study is to determine whether dietary
supplementation with soy isoflavones has effects in patients with asthma. 20 patients with
asthma will supplement their diet with a soy isoflavone capsule for 4 weeks. Before and after
the supplementation period, we will measure lung function, exhaled nitric oxide (a marker for
airway inflammation), collect exhaled breath condensate to measure levels of inflammatory
mediators in the airways, and isolate peripheral blood eosinophils to assess the impact of
soy isoflavones on their function. We hypothesize that dietary supplementation with soy
isoflavones will reduce exhaled nitric oxide level, reduce the inflammatory mediators in the
exhaled breath condensate, and reduce the ability of eosinophils to release inflammatory
molecules. Identifying if these hypothesized effects of soy isoflavones exist in asthma will
provide a justification for further clinical studies.