Air Pollution ToxicityNEATNCT03314987
Nucleophilic Defense Against PM Toxicity (NEAT Trial)
A study testing L-carnosine in people with Air Pollution Toxicity, run by University of Louisville at 1 site in United States.
Trial summary
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… Read more about this study
- Who is it for?
- Ages 22 to 65 yearsHealthy volunteers can take part
- Conditions the study is for
- Air Pollution Toxicity
- What is being tested?
- L-carnosine
- Type of treatment
- Pill or oral medicine
- Could I receive a placebo?
- Yes, some participants may receive a placebo
- How many people
- 299 participants
- Where
- 1 siteUnited States
- Study dates
- 1 Apr 2018to 1 Nov 2022
- Phase
- Interventional
- Are there results?
- Yes, posted in the registrySummary in the doctors' view
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 22 to 65 years
- All sexes
- Healthy volunteers accepted
- Adult, Older adult
Who may be able to join
- Individuals between 22-65 years of age of either gender and all ethnicities,
- All genders and all ethnicities
- Residing in or near the Louisville metropolitan area
- Consumes some type of meat/fish at least once a month during the past 3 months
- Carnosine levels below the median level of the population
- Agrees to complete all study visits and follow study intervention regimen
- Will be living in the study area throughout the study period, with no more than 1 week away from the study area.
Who cannot join
- Consumed any dietary supplement more than 3 times per week in the past 4 weeks (one month)
- Current / ongoing treatment for substance abuse
- Currently undergoing treatment or have conditions which may cause participant to be immunosuppressed
- 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.)
- Diseases Affecting Bone Marrow capacity
- Diagnosis of any active cancer
Show all 17Show fewer
- Recent organ / kidney transplant or replacement (Active/Long-Term Medications)
- Type 1 Diabetes Mellitus
- Untreated thyroid disease
- Untreated anemia
- Current acute infections (Influenza, fever, etc.)
- HIV positive status
- Active/current Hepatitis HepA, HepB or HepC or in past 6 months
- Currently or planning to be Pregnant / lactating
- Prisoners / vulnerable populations
- Other medical conditions that compromise completion of study
- Unwilling to provide consent
Trial locations and contacts
1 site in 1 country.
About this study
Official title: 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.
Read the 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.
- Conditions
- Air Pollution Toxicity
- Being tested
- L-carnosine, placebo
- Keywords
- air pollution, oxidative stress, intervention
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
L-carnosineDietary supplement
a naturally occurring di-peptide
placeboOther
an identically appearing supplement
| Study group | Role | What they receive |
|---|---|---|
| intervention group | Active comparator | Each participant will be given a daily oral dose of 2 grams of carnosine for 12 weeks Receives: Dietary Supplement: L-carnosine |
| placebo group | Placebo comparator | Each participant will be given a daily oral dose of 2 grams of placebo for 12 weeks Receives: Other: placebo |
What is being measured
The primary outcome is the main question the study is designed to answer.
Endothelial Progenitor Cells
circulating pro-angiogenic cells
Measured: 3 months
Secondary outcomes (3)
Augmentation Index
index of arterial function
Measured: 3 months
Endothelial Microparticles
index of endothelial damage
Measured: 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.
Platelet Monocyte Aggregates
percentage of CD14 events that are co-stained with CD41 (platelet glycoprotein GPIIb); also levels of CD62P (P-selectin) expression
Measured: 3 months
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted19 Oct 2017
- Study start1 Apr 2018
- Primary completion1 Nov 2022
- Study completion1 Nov 2022
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
- Publications (5)Papers the sponsor has linked to this study.
- Other trials for Air Pollution ToxicityStudies of the same condition, open and under way.
- More trials run by University of LouisvilleThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Model description
- placebo controlled, randomized, double-blind
- Masking
- Double blind
- Who is masked
- Participant, Investigator
- Enrolment
- 299 participants (actual)
Sponsor and investigators
- Lead sponsor
- University of Louisville
- Sponsor type
- University, hospital or other
- Collaborators
- National Institute of Environmental Health Sciences (NIEHS)
- Responsible party
- Principal investigator, Timothy Edward O'Toole, University of Louisville
- Investigators
- Timothy E. O'Toole, Principal investigator, University of Louisville
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT03314987
- Sponsor's protocol ID
- 20.0258
- Other IDs
- 5R01ES019217
- Acronym
- NEAT
- Status last verified
- Dec 2025
- First submitted
- 16 Oct 2017
- Last updated
- 6 Jan 2026
- Results posted
- Yes, on ClinicalTrials.gov
- Data monitoring committee
- Yes
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- No
Publications
O'Toole TE, Hellmann J, Wheat L, Haberzettl P, Lee J, Conklin DJ, Bhatnagar A, Pope CA 3rd. Episodic exposure to fine particulate air pollution decreases circulating levels of endothelial progenitor cells. Circ Res. 2010 Jul 23;107(2):200-3. doi: 10.1161/CIRCRESAHA.110.222679. Epub 2010 Jul 1.
PubMed 20595651Barski OA, Xie Z, Baba SP, Sithu SD, Agarwal A, Cai J, Bhatnagar A, Srivastava S. Dietary carnosine prevents early atherosclerotic lesion formation in apolipoprotein E-null mice. Arterioscler Thromb Vasc Biol. 2013 Jun;33(6):1162-70. doi: 10.1161/ATVBAHA.112.300572. Epub 2013 Apr 4.
PubMed 23559625Pope CA 3rd, Bhatnagar A, McCracken JP, Abplanalp W, Conklin DJ, O'Toole T. Exposure to Fine Particulate Air Pollution Is Associated With Endothelial Injury and Systemic Inflammation. Circ Res. 2016 Nov 11;119(11):1204-1214. doi: 10.1161/CIRCRESAHA.116.309279. Epub 2016 Oct 25.
PubMed 27780829Baba SP, Amraotkar AR, Hoetker D, Gao H, Gomes D, Zhao J, Wempe MF, Rice PJ, DeFilippis AP, Rai SN, Pope CA 3rd, Bhatnagar A, O'Toole TE. Evaluation of supplementary carnosine accumulation and distribution: an initial analysis of participants in the Nucleophilic Defense Against PM Toxicity (NEAT) clinical trial. Amino Acids. 2024 Aug 31;56(1):55. doi: 10.1007/s00726-024-03414-5.
PubMed 39215872O'Toole TE, Amraotkar AA, DeFilippis AP, Rai SN, Keith RJ, Baba SP, Lorkiewicz P, Crandell CE, Pariser GL, Wingard CJ, Pope Iii CA, Bhatnagar A. Protocol to assess the efficacy of carnosine supplementation in mitigating the adverse cardiovascular responses to particulate matter (PM) exposure: the Nucleophilic Defense Against PM Toxicity (NEAT) trial. BMJ Open. 2020 Dec 28;10(12):e039118. doi: 10.1136/bmjopen-2020-039118.
PubMed 33372072
Study at a glance
From the registry record, last updated by the sponsor on 6 Jan 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Nucleophilic Defense Against PM Toxicity
- ClinicalTrials.gov ID
- NCT03314987
- Acronym / sponsor ID
- NEAT / 20.0258
- Conditions
- Air Pollution Toxicity
- Keywords
- air pollution, oxidative stress, intervention
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 299 participants (actual)
- Lead sponsor
- University of LouisvilleUniversity, hospital or other
- Collaborators
- National Institute of Environmental Health Sciences (NIEHS)
- Study start
- 1 Apr 2018 (actual)
- Primary completion
- 1 Nov 2022 (actual)
- Study completion
- 1 Nov 2022 (actual)
- First posted
- 19 Oct 2017 (actual)
- Results
- Posted 18 Jun 2024
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
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 design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Double blind (participant, investigator)
- Number of arms
- 2
- Model description
- placebo controlled, randomized, double-blind
| Arm | Type | Receives |
|---|---|---|
| intervention group | Active comparator | Dietary Supplement: L-carnosineEach participant will be given a daily oral dose of 2 grams of carnosine for 12 weeks |
| placebo group | Placebo comparator | Other: placeboEach participant will be given a daily oral dose of 2 grams of placebo for 12 weeks |
Who may qualify
- Ages
- 22 to 65 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (7 listed)
- Individuals between 22-65 years of age of either gender and all ethnicities,
- All genders and all ethnicities
- Residing in or near the Louisville metropolitan area
- Consumes some type of meat/fish at least once a month during the past 3 months
- Carnosine levels below the median level of the population
Key exclusion criteria (17 listed)
- Consumed any dietary supplement more than 3 times per week in the past 4 weeks (one month)
- Current / ongoing treatment for substance abuse
- Currently undergoing treatment or have conditions which may cause participant to be immunosuppressed
- 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.)
- Diseases Affecting Bone Marrow capacity
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| L-carnosinea naturally occurring di-peptide | Dietary supplement | intervention group |
| placeboan identically appearing supplement | Other | placebo group |
Primary outcome
Endothelial Progenitor Cells
Time frame: 3 months
circulating pro-angiogenic cells
3 secondary outcomes
Augmentation Index
Time frame: 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.
Platelet Monocyte Aggregates
Time frame: 3 months
Results and safety
Loading the posted results from ClinicalTrials.gov…
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 6 Jan 2026.
- Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
- Background: PubMed 20595651O'Toole TE, Hellmann J, Wheat L, Haberzettl P, Lee J, Conklin DJ, Bhatnagar A, Pope CA 3rd. Episodic exposure to fine particulate air pollution decreases circulating levels of endothelial progenitor cells. Circ Res. 2010 Jul 23;107(2):200-3. doi: 10.1161/CIRCRESAHA.110.222679. Epub 2010 Jul 1.
- Results publication: PubMed 23559625Barski OA, Xie Z, Baba SP, Sithu SD, Agarwal A, Cai J, Bhatnagar A, Srivastava S. Dietary carnosine prevents early atherosclerotic lesion formation in apolipoprotein E-null mice. Arterioscler Thromb Vasc Biol. 2013 Jun;33(6):1162-70. doi: 10.1161/ATVBAHA.112.300572. Epub 2013 Apr 4.
- Results publication: PubMed 27780829Pope CA 3rd, Bhatnagar A, McCracken JP, Abplanalp W, Conklin DJ, O'Toole T. Exposure to Fine Particulate Air Pollution Is Associated With Endothelial Injury and Systemic Inflammation. Circ Res. 2016 Nov 11;119(11):1204-1214. doi: 10.1161/CIRCRESAHA.116.309279. Epub 2016 Oct 25.
- Derived from this study: PubMed 39215872Baba SP, Amraotkar AR, Hoetker D, Gao H, Gomes D, Zhao J, Wempe MF, Rice PJ, DeFilippis AP, Rai SN, Pope CA 3rd, Bhatnagar A, O'Toole TE. Evaluation of supplementary carnosine accumulation and distribution: an initial analysis of participants in the Nucleophilic Defense Against PM Toxicity (NEAT) clinical trial. Amino Acids. 2024 Aug 31;56(1):55. doi: 10.1007/s00726-024-03414-5.
- Derived from this study: PubMed 33372072O'Toole TE, Amraotkar AA, DeFilippis AP, Rai SN, Keith RJ, Baba SP, Lorkiewicz P, Crandell CE, Pariser GL, Wingard CJ, Pope Iii CA, Bhatnagar A. Protocol to assess the efficacy of carnosine supplementation in mitigating the adverse cardiovascular responses to particulate matter (PM) exposure: the Nucleophilic Defense Against PM Toxicity (NEAT) trial. BMJ Open. 2020 Dec 28;10(12):e039118. doi: 10.1136/bmjopen-2020-039118.
- Individual participant dataSharing planned: No
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Timothy E. O'Toole principal investigator
University of Louisville
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing L-carnosine in people with Air Pollution Toxicity, run by University of Louisville at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 7 inclusion and 17 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 6 Jan 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. Some participants in this study may receive a placebo. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Yes. Results are posted in the registry (first posted 18 Jun 2024). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Endothelial Progenitor Cells (time frame: 3 months). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT03314987, which also lists 5 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 6 Jan 2026.