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Dietary Supplementation With Soy Isoflavones in Asthma

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details. Identifier: NCT00277446
Recruitment Status : Completed
First Posted : January 16, 2006
Results First Posted : February 24, 2011
Last Update Posted : February 25, 2011
Information provided by:
Northwestern University

Brief 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.

Condition or disease Intervention/treatment Phase
Asthma Drug: Soy isoflavones Not Applicable

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.

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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 13 participants
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Dietary Supplementation With Soy Isoflavones in Asthma
Study Start Date : January 2006
Actual Primary Completion Date : April 2007
Actual Study Completion Date : April 2007

Resource links provided by the National Library of Medicine

Primary Outcome Measures :
  1. Exhaled Nitric Oxide [ Time Frame: 0 and 4 weeks ]
    Exhaled nitric oxide at baseline (week 0) and at 4 weeks

Secondary Outcome Measures :
  1. Eosinophil LTC4 Synthesis [ Time Frame: 0 and 4 weeks ]
    Peripheral blood eosinophils were isolated before and after treatment with Novasoy, stimulated with calcium ionophore, and the amount of leukotriene C4 (LTC4) produced was measured by EIA.

  2. Forced Expiratory Volume in One Second (FEV1) [ Time Frame: 0 and 4 weeks ]
    Forced expiratory volume in one second (FEV1) measured as liters/second

Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years to 50 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Ages 18-50, males and females
  • Physician diagnosis of asthma; requires daily asthma medication
  • Moderate persistent disease (NAEPP guidelines)
  • FEV1 65 to 90% of predicted
  • At least 12% increase in FEV1 15-30 minutes after inhaling 2-4 puffs of albuterol or positive methacholine challenge (20% fall in FEV1 at less than 8 mg/ml) - either of these can available from the previous 2 years
  • Generally good health

Exclusion Criteria:

  • Oral corticosteroid use within the past 3 months
  • Use of high dose inhaled corticosteroids (greater than 500 mcg of fluticasone per day or greater)
  • Current or former smoker (quit less than 6 months prior to study enrollment or greater than 10 pack years)
  • Recent asthma exacerbation (within 6 weeks)
  • Current consumption of soy isoflavone supplements
  • Known adverse reaction to genistein, other phytoestrogens, or soy products
  • Pregnant
  • Unintentional weight loss of more than 10 pounds within the year
  • Major or unstable medical condition
  • Use of an investigational drug in the previous 30 days

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its identifier (NCT number): NCT00277446

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United States, Illinois
Northwestern University
Chicago, Illinois, United States, 60611
Sponsors and Collaborators
Northwestern University
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Principal Investigator: Lewis J Smith, MD Northwestern University
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Responsible Party: Lewis Smith/Professor of Medicine, Northwestern University Identifier: NCT00277446    
Other Study ID Numbers: 0456-035
First Posted: January 16, 2006    Key Record Dates
Results First Posted: February 24, 2011
Last Update Posted: February 25, 2011
Last Verified: February 2011
Keywords provided by Northwestern University:
Soy isoflavones
Exhaled nitric oxide
Additional relevant MeSH terms:
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Bronchial Diseases
Respiratory Tract Diseases
Lung Diseases, Obstructive
Lung Diseases
Respiratory Hypersensitivity
Hypersensitivity, Immediate
Immune System Diseases