FIRE-Diet: Food as an Intervention to Reduce the Effects of Woodsmoke Exposure on Respiratory Health

NCT06711614 | Recruiting

• 1 other identifier: H23-03904
• Study Type: interventional
• Target: 48
• Locations: 1 country
• Sites: 1

Brief Summary

Research suggests that consuming more fatty fish, fruits, and vegetables could potentially shield the lungs from the negative impacts of air pollution. The research team will look at whether a dietary intervention aimed at increasing intake of these foods can protect the lungs from woodsmoke as the air pollutant and look into how this works.

Conditions

Healthy Individuals

Keywords

Diet Intervention; EPA; DHA; Omega-3 fatty acids

Outcome Measures

Primary Outcomes (4)

• Within-individual change in sputum neutrophil %

  Within-individual change in sputum neutrophil %, compared across Intervention and Control Diet periods post wood smoke exposures.

  Across study duration, anticipated ~15 weeks.

• Within-individual change in sputum neutrophil activation and function

  Within-individual change in sputum neutrophil activation (expression of neutrophil activation cell surface markers, release of neutrophil elastase and myeloperoxidase), and neutrophil function (phagocytosis, intracellular oxidative burst, and extracellular trap formation) across Intervention and Control Diet periods post wood smoke exposures.

  Across study duration, anticipated ~15 weeks

• Within-individual change in airway resistance

  Within-individual change in airway resistance, as measured by impulse oscillometry (resonant frequency (Fres) and peripheral airway resistance (R5-R20)) across Intervention and Control Diet periods post wood smoke exposures.

  Across study duration, anticipated ~15 weeks.

• Within-individual change in sputum biomarkers of inflammation

  Within-individual change in sputum biomarkers of inflammation (IL-6, IL-8, and TNF-alpha in sputum as well as fractional exhaled nitric oxide) across Intervention and Control Diet periods post wood smoke exposures.

  Across study duration, anticipated ~15 weeks.

Secondary Outcomes (6)

• Within-individual change in sputum biomarkers/arbiters of inflammation

  Across study duration, anticipated ~15 weeks.

• Within-individual change in upper airway (nasal) markers of neutrophil activation and function

  Across study duration, anticipated ~15 weeks.

• Within-individual change in upper airway (nasal) biomarkers/arbiters of inflammation

  Across study duration, anticipated ~15 weeks.

• Within-individual change in blood neutrophil %

  Across study duration, anticipated ~15 weeks.

• Within-individual change in blood neutrophil activation and function

  Across study duration, anticipated ~15 weeks

Other Outcomes (1)

• Within-individual change in systemic biomarkers/arbiters of inflammation and oxidative stress

  Across study duration, anticipated ~15 weeks.

Study Arms (2)

Intervention Diet First, then Control Diet

OTHER

Participants will complete \~4 weeks of the Intervention Diet, followed by a washout period of at least 4 weeks, then \~4 weeks of the Control Diet. At the end of each Diet period, participants will undergo a 2 hour controlled wood smoke exposure, following which outcome measures will be assessed.

Other: Intervention Diet; Other: Control Diet

Control Diet First, then Intervention Diet

OTHER

Participants will complete \~4 weeks of the Control Diet, followed by a washout period of at least 4 weeks, then \~4 weeks of the Intervention Diet. At the end of each Diet period, participants will undergo a 2 hour controlled wood smoke exposure, following which outcome measures will be assessed.

Other: Intervention Diet; Other: Control Diet

Interventions

Control Diet OTHER

Participants will receive weekly food subsidies for their groceries for 4-weeks (\~equivalent to the subsidies to provide groceries in the Intervention arm) but are free to purchase whatever they wish. The participants will continue to have dietician counseling during this time.

Control Diet First, then Intervention Diet; Intervention Diet First, then Control Diet

Intervention Diet OTHER

Designed to increase Omega-3 Fatty Acids (Eicosapentaenoic acid (EPA), Docosahexaenoic acid (DHA)), fruit, and vegetable intake, participants will receive grocery and meal deliveries for approximately 4-weeks via online ordering with dietician counselling.

Control Diet First, then Intervention Diet; Intervention Diet First, then Control Diet

Eligibility Criteria

• Age: 19 Years - 40 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Healthy, and specifically with no respiratory disease
• Not taking any supplements, or willing to abstain from supplement use for 4-weeks prior to study start and the whole duration of the study,
• Must currently consume, on average, less than 2 servings of fish per week and fewer than 5 servings of fruits and vegetables per day based on screening questionnaires.
• Must have a null GSTM1 genotype determined at screening.
• Must be able to provide a sufficient sputum sample during the screening visit.

You may not qualify if:

• Pregnant or planning to become pregnant during the study period.
• Health conditions that would pose an unacceptable risk of dietary change, or conditions that are uncontrolled based on principal investigator's judgement.
• Actively attempting to lose weight.
• Frequent wood smoke exposure (e.g. at home or employment).
• Unable to store provided meals and food safely.
• Food allergies/intolerance or food aversion preventing adherence to the intervention diet, or unwillingness/medically unable to adjust diet in line with the intervention.
• Relocation during the study period to an area which will prevent food delivery.
• History of smoking tobacco, marijuana, or and other substance or vaping within the past 6 months, or having smoked the equivalent of 0.5 pack-years ever.
• Body mass index (BMI) \<18.5, as determined during the in-person screening visit.

Sponsors & Collaborators

• University of British Columbia: lead

Study Sites (1)

University of British Columbia

Vancouver, British Columbia, V5Z 1M9, Canada

RECRUITING

Study Officials

• Emily Brigham, MD

  University of British Columbia

  PRINCIPAL INVESTIGATOR

Central Study Contacts

Agustin Bueso

CONTACT

604-875-4111; agustin.bueso@ubc.ca

Agnes Yuen

CONTACT

604-875-4111; agnes.yuen@ubc.ca

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: INVESTIGATOR
• Masking Details: environmental engineer (administering the woodsmoke exposure) will be masked to diet assignment
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor

Model Details: Each participant will be randomized to begin the study with the control diet (their usual diet) or the intervention diet (aimed at increasing intake of fatty fish high in omega-3 fatty acids, fruits, and vegetables) x \~4 weeks. After a washout period of at least 4 weeks the participant will complete the alternate assignment. At the end of each assignment (control or intervention diet) the participant will undergo a controlled exposure to wood smoke x 2 hours, following which lung health outcomes will be assessed as described.

Study Record Dates

• First Submitted: October 18, 2024
• First Posted: December 2, 2024
• Study Start: June 17, 2025
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2029
• Last Updated: February 13, 2026

Record last verified: 2025-05

Locations

CA (1)