Modification of Asthma With Soy Isoflavone

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: NCT00741208
Recruitment Status : Completed
First Posted : August 26, 2008
Last Update Posted : June 8, 2011
Respiratory Health Association of Metropolitan Chicago
Information provided by:
Northwestern University

Brief Summary:
The purpose of this study is to determine if dietary supplementation with soy isoflavones in persistent asthma improves airway reactivity as determined by PC20 to methacholine.

Condition or disease Intervention/treatment Phase
Asthma Dietary Supplement: Soy Isoflavone Not Applicable

Detailed Description:

Asthma is a complex disease whose prevalence and severity are determined by multiple genetic and environmental factors. The prevalence of asthma has increased during the past few decades. Although causal relationships have not been proven, changing dietary practices have paralleled the increase in asthma prevalence. Several surveys have found an association between reduced lung function and decreased consumption of antioxidants, flavonoids, and essential vitamins in a variety of respiratory conditions including asthma. These findings suggest that diet may be a factor that impacts asthma and its clinical manifestations.

Higher dietary consumption of soy isoflavones is associated with decreased self-report of cough and other allergic respiratory symptoms. Our group reported an inverse relationship between dietary intake of the soy isoflavone genistein and asthma severity. In addition, we recently demonstrated that genistein inhibits synthesis of cysteinyl-leukotrienes in eosinophils by blocking p38-dependent activation of 5-lipoxygenase, providing a plausible cellular mechanism for the benefit of soy isoflavones in asthma. We also documented that dietary soy isoflavone supplementation in asthma patients inhibited eosinophil cysteinyl-leukotriene synthesis and decreased exhaled nitric oxide, an indicator of eosinophilic airway inflammation. Our overall long-term goal is to translate these epidemiological and mechanistic findings to human disease and determine whether dietary soy isoflavones have a clinical role in asthma. We propose a clinical study powered to detect an improvement in lung function as the first stop in achieving this goal.

Our hypothesis is that dietary supplementation with isoflavones will improve lung function, reduce symptoms, and decrease airway inflammation in asthma. To test this, we will conduct a randomized placebo-controlled, cross-over study of soy isoflavone supplementation in patients with persistent asthma.

Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 20 participants
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Official Title: Modification of Asthma With Soy Isoflavone
Study Start Date : August 2008
Actual Primary Completion Date : November 2010
Actual Study Completion Date : November 2010

Resource links provided by the National Library of Medicine

MedlinePlus related topics: Asthma
U.S. FDA Resources

Arm Intervention/treatment
Patients randomized to receive soy isoflavone twice daily for 2 weeks. Patients will cross-over and receive placebo medication for 2 weeks later in the study
Dietary Supplement: Soy Isoflavone
50mg soy isoflavone supplement consumed twice daily for a total of 100mg of soy isoflavones per day.
Patients randomized to receive placebo medication twice daily for 2 weeks. Patients will cross-over and receive soy isoflavone for 2 weeks later in the study
Dietary Supplement: Soy Isoflavone
50mg soy isoflavone supplement consumed twice daily for a total of 100mg of soy isoflavones per day.

Primary Outcome Measures :
  1. Change in airway reactivity induced by dietary supplementation with soy isoflavones. Airway reactivity will be measured with methacholine bronchoprovocation testing. [ Time Frame: 6 weeks ]

Secondary Outcome Measures :
  1. Change in FEV1, morning peak flow rate, asthma control, markers of airway hyperreactivity and inflammation including sputum eosinophilia and eosinophilic cationic protein, fraction of expired nitric oxide, and urinary leukotriene. [ Time Frame: 6 weeks ]

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Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • 18 years of age or older;
  • Physician diagnosed asthma;
  • Positive methacholine bronchoprovocation test (20% fall in FEV1 at less than 8 mg/ml) with the past 3 years;
  • Smoking Status: non-smoker for 6 months or longer and a less than 10 pack-year cumulative smoking history.

Exclusion Criteria:

  • Pulmonary function FEV1< 70% predicted pre-bronchodilator;
  • Other major chronic illness: conditions that in the judgement of athe principle investigator would interfere with participation in the study or history of or physician diagnosis of COPD, emphysema, or chronic bronchitis;
  • Medication use: current consumption of soy isoflavone supplements or oral corticosteroid use within the past 6 months OR use of an investigational treatment within the previous 30 days;
  • Drug allergy: known adverse reaction to genistein, other phytoestrogens, or soy products;
  • Females of childbearing potential: pregnant or lactating or women of appropriate ago who report the possibility of pregnancy at the time of enrollment will be screened and cannot participate if pregnant;
  • Non-adherence: inability or unwillingness to provide informed consent or inability to swallow study medication or inability to perform baseline measurements or completion of fewer than 5 of the 7 days of screening period diary entry or inability to be contacted by telephone;
  • Other exclusions: recent asthma exacerbation (within 6 weeks) or recent upper respiratory tract infection (within 2 weeks) or change in diet over the past 1 month or expected change in diet (for example a weight loss diet) during the 6 week study period.

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): NCT00741208

United States, Illinois
Northwestern University
Chicago, Illinois, United States, 60611
Sponsors and Collaborators
Northwestern University
Respiratory Health Association of Metropolitan Chicago
Principal Investigator: Ravi Kalhan, MD, MS Northwestern University

Responsible Party: Ravi Kalhan, MD, MS, Northwestern University Identifier: NCT00741208     History of Changes
Other Study ID Numbers: 2804
First Posted: August 26, 2008    Key Record Dates
Last Update Posted: June 8, 2011
Last Verified: June 2011

Keywords provided by Northwestern University:
soy isoflavone

Additional relevant MeSH terms:
Bronchial Diseases
Respiratory Tract Diseases
Lung Diseases, Obstructive
Lung Diseases
Respiratory Hypersensitivity
Hypersensitivity, Immediate
Immune System Diseases