Nucleophilic Defense Against PM Toxicity (NEAT Trial) (NEAT)

December 16, 2025 updated by: Timothy Edward O'Toole, University of Louisville

Nucleophilic Defense Against PM Toxicity

Carnosine is a naturally occurring peptide found in high levels in skeletal muscle and the brain and is also available commercially as a dietary supplement. Since carnosine has anti-oxidant properties and air pollution exposure induces a state of oxidative stress, the purpose of this study is to see if those taking carnosine as a dietary supplement are protected from air pollution-induced oxidative stress and adverse cardiovascular outcomes.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

This is a placebo controlled, randomized, double-blind, interventional trial investigating the efficacy of carnosine in reducing the effects of particulate matter air pollution (PM2.5). A total of 240 participants from the Louisville metropolitan and neighboring areas will be randomized into two dietary supplement study groups - carnosine (n=120) versus placebo (n=120). Intervention of study dietary supplements will occur from May through September, when the levels of PM2.5.are highest in the Louisville, KY area. Study participants will be given a daily oral dose of total of 2 grams of carnosine (or placebo) for a total of 12 consecutive weeks (during May through September).

Urinary levels of carnosine will be used to screen and identify potential candidates with low carnosine levels. Those with levels less than the median levels of the population, will be invited to participate in the study. The following measurements will be performed - blood and urine sample collection, physical examination, arterial stiffness, physical function, and self-reported surveys on environmental exposure, sleep, diet, and exercise. Supplement intervention (carnosine or placebo) will be initiated at the time of Baseline Assessment and will continue for 12 weeks from that date. Two follow up visits will occur at 6 weeks and 12 weeks respectively after initiating supplementation.

This innovative clinical investigation will provide an insight into the pre and post intervention effects of a cheap, safe, and over-the-counter available dietary supplement in countering the effects of air pollution.

Study Type

Interventional

Enrollment (Actual)

299

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • United States
    • Kentucky
      • Louisville, Kentucky, United States, 40202
        • Clinical Trials Unit

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

22 years to 65 years (Adult, Older Adult)

Accepts Healthy Volunteers

Yes

Description

Inclusion Criteria:

  1. Individuals between 22-65 years of age of either gender and all ethnicities,
  2. All genders and all ethnicities
  3. Residing in or near the Louisville metropolitan area
  4. Consumes some type of meat/fish at least once a month during the past 3 months
  5. Carnosine levels below the median level of the population
  6. Agrees to complete all study visits and follow study intervention regimen
  7. Will be living in the study area throughout the study period, with no more than 1 week away from the study area.

Exclusion Criteria:

  1. Consumed any dietary supplement more than 3 times per week in the past 4 weeks (one month)
  2. Current / ongoing treatment for substance abuse
  3. Currently undergoing treatment or have conditions which may cause participant to be immunosuppressed
  4. Diseases Affecting Peripheral Cell Count (i.e. Autoimmune Diseases - Hashimoto, Rheumatoid Arthritis, SLE, Rheumatoid Arthritis, Sjogren syndrome, Ankylosing Spondylitis, Takayasu arteritis, Kawasaki disease, Polyarteritis nodosa.)
  5. Diseases Affecting Bone Marrow capacity
  6. Diagnosis of any active cancer
  7. Recent organ / kidney transplant or replacement (Active/Long-Term Medications)
  8. Type 1 Diabetes Mellitus
  9. Untreated thyroid disease
  10. Untreated anemia
  11. Current acute infections (Influenza, fever, etc.)
  12. HIV positive status
  13. Active/current Hepatitis HepA, HepB or HepC or in past 6 months
  14. Currently or planning to be Pregnant / lactating
  15. Prisoners / vulnerable populations
  16. Other medical conditions that compromise completion of study
  17. Unwilling to provide consent

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Double

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Active Comparator: intervention group
Each participant will be given a daily oral dose of 2 grams of carnosine for 12 weeks
Dietary supplement: L-carnosine
a naturally occurring di-peptide
Placebo Comparator: placebo group
Each participant will be given a daily oral dose of 2 grams of placebo for 12 weeks
Other: placebo
an identically appearing supplement

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Endothelial Progenitor Cells
Time Frame: 3 months
circulating pro-angiogenic cells
3 months

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Augmentation Index
Time Frame: 3 months
index of arterial function
3 months
Platelet Monocyte Aggregates
Time Frame: 3 months
percentage of CD14 events that are co-stained with CD41 (platelet glycoprotein GPIIb); also levels of CD62P (P-selectin) expression
3 months
Endothelial Microparticles
Time Frame: Samples were collected from each participant at baseline, after ~6wk of intervention, and after ~12wk of intervention. Measurement will be performed on archived samples once assay is in place.
index of endothelial damage
Samples were collected from each participant at baseline, after ~6wk of intervention, and after ~12wk of intervention. Measurement will be performed on archived samples once assay is in place.

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Louisville

Collaborators

National Institute of Environmental Health Sciences (NIEHS)

Investigators

  • Principal Investigator: Timothy E. O'Toole, University of Louisville

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

April 1, 2018

Primary Completion (Actual)

November 1, 2022

Study Completion (Actual)

November 1, 2022

Study Registration Dates

First Submitted

October 16, 2017

First Submitted That Met QC Criteria

October 16, 2017

First Posted (Actual)

October 19, 2017

Study Record Updates

Last Update Posted (Estimated)

January 6, 2026

Last Update Submitted That Met QC Criteria

December 16, 2025

Last Verified

December 1, 2025

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 20.0258
  • 5R01ES019217 (U.S. NIH Grant/Contract)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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