Improving asthma in veterans using L-citrulline supplementation

Study to Improve dEployment Related Asthma by Using L-citrulline Supplementation (SEALS)

PHASE2 · University of Colorado, Denver · NCT05259904

This study is testing if L-citrulline supplements can help veterans with asthma related to their military service feel better and breathe easier.

Quick facts

PhasePHASE2
Study typeInterventional
Enrollment75 (estimated)
Ages18 Years to 70 Years
SexAll
SponsorUniversity of Colorado, Denver (other)
Locations1 site (Denver, Colorado)
Trial IDNCT05259904 on ClinicalTrials.gov

What this trial studies

This study investigates the effects of L-citrulline supplementation on service members who have developed asthma related to their deployment. It aims to address the complex airway disease that often does not respond to standard asthma medications, particularly in those exposed to environmental factors like diesel and burn pits. Participants will receive either L-citrulline or a placebo, and their respiratory function will be monitored to assess improvements in symptoms and quality of life.

Who should consider this trial

Good fit: Ideal candidates are male and female veterans aged 18 to 70 with deployment-related asthma and suboptimal asthma control.

Not a fit: Patients with well-controlled asthma or those who do not meet the criteria for deployment-related asthma may not benefit from this study.

Why it matters

Potential benefit: If successful, this treatment could provide a new, safe, and affordable option for improving asthma symptoms in veterans.

How similar studies have performed: While the approach of using L-citrulline for asthma is novel, previous studies have indicated that amino acid regulation may play a role in asthma management.

Eligibility criteria

Show full inclusion / exclusion criteria
Inclusion Criteria:

* Adequate completion of informed consent process with written documentation
* Male and female patients, 18 - 70 years old, inclusive
* Meets criteria for deployment related asthma or DRA (New onset of persistent respiratory symptoms of cough, dyspnea, wheezing and/or chest tightness during or after post-9/11/2001 military deployment to Southwest Asia, accompanied by a post-bronchodilator increase in FEV1 ≥ 12% and an increase in FEV1 ≥ 200 milliliters on pulmonary function testing and/or methacholine challenge showing airways hyperresponsiveness with a 20 percent drop in FEV1 (PC\[-20\] FEV1) ≤ 16 mg/mL. ) Historical results from previous studies or documented in clinical records within the last 24 months are acceptable alternatives
* Able to perform reproducible spirometry according to ATS criteria
* All racial/ethnic backgrounds may participate
* Smoking tobacco history ≤15 pack years and no smoking in the last 3 months
* Suboptimal asthma control at baseline (ACQ ≥ 0.5 or ACT\<19)

Exclusion Criteria:

* Respiratory tract infection within the 4 weeks prior to Visit 0
* Pulmonary-related ER visit within the 4 weeks prior to Visit 0
* Oral or systemic corticosteroid burst (for any indication) within the 4 weeks prior to Visit 0. One-time doses, such as intra-articular injections into a shoulder or knee joint, require a 2-week washout prior to Visit 0
* Significant concomitant medical illness at the discretion of the PI, including (but not limited to) heart disease, cancer, uncontrolled diabetes, other chronic lung diseases
* Chronic renal failure (creatinine \> 2.0) at Visit 0 (Associated with higher ADMA levels)
* Positive urine (or serum) pregnancy test at Visit 0 or at any time during the study
* Intolerance or allergy to L-arginine or L-citrulline
* Concomitant use of PDE5 drugs or oral mononitrates
* Unable or unlikely to complete study assessments in the opinion of the Investigator
* Study intervention poses undue risk to patient in the opinion of the Investigator

Where this trial is running

Denver, Colorado

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.

View on ClinicalTrials.gov →

Conditions: Post Deployment Related Asthma, Asthma

Last reviewed 2026-05-15 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.