Dietary Supplementation With Soy Isoflavones in Asthma
Condition: Asthma
MeSH terms: Asthma
Study type: Interventional

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.
    

Detailed description: 
      This is a prospective pilot study to be conducted in 20 subjects with asthma. The participant
      will undergo the following procedures:

        1. Completion of a questionnaire that asks for information about asthma including symptoms,
           medications, and ability to participate in activities.

        2. Measurement of exhaled nitric oxide (NO) in which subjects will breathe slowly into a
           tube. This test takes about 5 minutes.

        3. Collection of the air exhaled from the lungs and condensing it into a liquid form. This
           is called an exhaled breath condensate. This procedure involves breathing slowing into a
           tube for a period of 15 minutes. The measurements determined by this method are
           exclusively for research purposes and not used in routine clinical settings.

        4. Measurement of lung function with a spirometer. This involves breathing in and out
           forcefully through a mouthpiece.

        5. Collection of 60 ml (4 tablespoons) of blood to measure genistein (the major component
           of the soy isoflavone) levels and eosinophil function. These measurements are also for
           research purposes and not routinely used clinically.

      Each of the above measurements will be made before and after the 4 week period of dietary
      supplementation with soy isoflavones.
    

Intervention name(s): Soy isoflavones
Intervention type(s): Drug
Allocation: Non-Randomized
Intervention model: Single Group Assignment
Masking: None (Open Label)
Primary purpose: Treatment
Keywords: Asthma; Soy isoflavones; Eosinophils; Exhaled nitric oxide