Effect of a Dietary Supplement Versus Placebo on Serum PFAS Levels in Male Firefighters

NCT07846371 | Not Yet Recruiting

• 1 other identifier: CB-AFCRO202-2026-10
• Study Type: interventional
• Target: 70
• Locations: 1 country
• Sites: 1

Brief Summary

This study is designed to evaluate the effect of a probiotic dietary supplement containing Streptococcus salivarius on serum PFAS levels in male firefighters with documented occupational PFAS exposure, following twice-daily use over a 12-week period.

Conditions

Environmental Exposure; PFAS Exposure

Keywords

Cross-over study; Serum PFAS levels; Gut Microbiome; Streptococcus salivarius; Dietary Supplement; Probiotic; Occupational Exposure; Firefighters; Forever Chemicals; Per- and Polyfluoroalkyl Substances

Outcome Measures

Primary Outcomes (1)

• Change in serum linear perfluorooctane sulfonic acid (n-PFOS)

  Change in serum n-PFOS concentration (ng/mL) from baseline to end of each 84-day intervention period, comparing the dietary supplement with placebo.

  Baseline (Day 0) to Day 84 of each intervention period

Secondary Outcomes (4)

• Change in pre-specified serum PFAS levels

  Baseline (Day 0) to Day 84 of each intervention period

• Change in composite serum PFAS measure

  Baseline (Day 0) to Day 84 of each intervention period

• Change in gastrointestinal symptoms (GSRS)

  Baseline (Day 0) to Day 84 of each intervention period

• Change in fatigue (MFIS)

  Baseline (Day 0) to Day 84 of each intervention period

Other Outcomes (6)

• Change in fecal PFAS levels

  Baseline (Day 0) to Day 84 of each intervention period

• Change in fecal microbiome composition

  Baseline (Day 0) to Day 84 of each intervention period

• Change in fecal metabolite profiles

  Baseline (Day 0) to Day 84 of each intervention period

Study Arms (2)

Sequence A: Study Product then Placebo

EXPERIMENTAL

Participants consume the probiotic dietary supplement (one capsule twice daily) for 84 days, followed by a 28-day washout, then placebo (one capsule twice daily) for 84 days.

Dietary Supplement: Streptococcus salivarius 46-SL1; Dietary Supplement: Placebo

Sequence B: Placebo then Study Product

PLACEBO COMPARATOR

Participants consume placebo (one capsule twice daily) for 84 days, followed by a 28-day washout, then the probiotic dietary supplement (one capsule twice daily) for 84 days.

Dietary Supplement: Streptococcus salivarius 46-SL1; Dietary Supplement: Placebo

Interventions

Streptococcus salivarius 46-SL1 DIETARY_SUPPLEMENT

One capsule (\~400 mg live probiotic) consumed twice daily with water, in the morning with breakfast and with the evening meal, for 84 days.

Sequence A: Study Product then Placebo; Sequence B: Placebo then Study Product

Placebo DIETARY_SUPPLEMENT

Matching placebo capsule containing microcrystalline cellulose, magnesium stearate and silicon dioxide, consumed twice daily with water for 84 days.

Sequence A: Study Product then Placebo; Sequence B: Placebo then Study Product

Eligibility Criteria

• Age: 18 Years+
• Sex: male
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Able to give written informed consent
• Male firefighter with previous career exposure to PFAS
• BMI between 18.5 and 35 kg/m²
• Serum PFOS level ≥5 ng/mL at screening
• Willing to consume the study product daily for the duration of the study

You may not qualify if:

• History of drug and/or alcohol abuse (\>15 standard drinks per week)
• Food allergy, intolerance or dietary restriction that, in the opinion of the investigator, would preclude consumption of the study product
• Blood donation within the past 3 months
• Current smoker of \>20 cigarettes per day, or former smoker with a history of ≥20 cigarettes per day who quit within 6 months prior to Visit 1
• Any significant acute or chronic health condition that would prevent participation, pose a risk, or confound interpretation of results, including: diagnosed gastrointestinal disorders (irritable bowel syndrome, inflammatory bowel disease, Crohn's disease, ulcerative colitis, coeliac disease, or other chronic diarrhoeal disorders); uncontrolled medical conditions; history of chronic kidney or liver disease; chronic inflammatory or autoimmune disease; history of gastrointestinal surgery; hospitalisation within the past 3 months
• Current or recent (past 12 weeks) use of medications affecting bile acid metabolism (e.g. bile acid sequestrants, fibrates) or antibiotics
• Current or recent (past 4 weeks) use of supplements affecting gut microbiota (prebiotics, probiotics, postbiotics, fibres, synbiotics), detoxification pathways (milk thistle, N-acetylcysteine, glutathione) or bile acid metabolism (e.g. psyllium husk)
• Current or recent (past 2 weeks) consumption of prohibited foods, including probiotic yoghurts
• Considered by the investigator unlikely to comply with study requirements
• Current participation in another clinical study, or insufficient time elapsed since a previous experimental study

Sponsors & Collaborators

• Cambiotics ApS: lead
• Atlantia Food Clinical Trials: collaborator

Study Sites (1)

Atlantia Clinical Trials

Chicago, Illinois, 60611, United States

Location

Related Publications (1)

• Lindell AE, Griesshammer A, Michaelis L, Papagiannidis D, Ochner H, Kamrad S, Guan R, Blasche S, Ventimiglia LN, Ramachandran B, Ozgur H, Zelezniak A, Beristain-Covarrubias N, Yam-Puc JC, Roux I, Barron LP, Richardson AK, Martin MG, Benes V, Morone N, Thaventhiran JED, Bharat TAM, Savitski MM, Maier L, Patil KR. Human gut bacteria bioaccumulate per- and polyfluoroalkyl substances. Nat Microbiol. 2025 Jul;10(7):1630-1647. doi: 10.1038/s41564-025-02032-5. Epub 2025 Jul 1.

  PMID: 40595288 BACKGROUND

MeSH Terms

Conditions

Progressive Encephalomyelitis with Rigidity

Study Officials

• Klavs Kirk

  Cambiotics ApS

  STUDY DIRECTOR

• Stacey Boetto, DNP, FNP-C

  Atlantia Food Clinical Trials

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Abigail O'Mahony, Operations Manager

CONTACT

+1 312 535-9440; aomahoney@atlantiatrials.com

Stacey Boetto, Princpal Investigator, DNP, FNP-C

CONTACT

312-535-9440; sboetto@atlantiatrials.com

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: TRIPLE
• Who Masked: PARTICIPANT, INVESTIGATOR, OUTCOMES ASSESSOR
• Masking Details: The Sponsor is also blinded to treatment allocation. The randomization list is prepared by a statistician not involved in the conduct of the study.
• Purpose: BASIC SCIENCE
• Intervention Model: CROSSOVER
• Sponsor Type: INDUSTRY
• Responsible Party: SPONSOR

Model Details: Two-period, two-sequence crossover. Participants are randomized 1:1 to the order of study product and placebo, with each 84-day intervention period separated by a 28-day washout.

Study Record Dates

• First Submitted: September 23, 2026
• First Posted: September 29, 2026
• Study Start (Estimated): November 1, 2026
• Primary Completion (Estimated): November 1, 2027
• Study Completion (Estimated): November 1, 2027
• Last Updated: October 1, 2026

Record last verified: 2026-09

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)