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

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.

Study Overview

• Status: Recruiting
• Conditions: Healthy Individuals
• Intervention / Treatment: Other: Intervention Diet; Other: Control Diet

Detailed Description

This study aims to recruit 48 healthy adult volunteer participants (24 male and 24 female biologic sex assigned at birth) with no known respiratory diseases (as assessed by the study physician) who will breathe in woodsmoke while they are supported to eat a diet higher in fatty fish, fruits, and vegetables (the intervention diet), or not (the control diet).

All participants will undergo a screening visit to assess eligibility for the study. Once deemed eligible, they will experience three exposure visits: one fresh air (filtered air - FA) exposure and two woodsmoke (WS) exposures. The study will span a minimum duration of 15 weeks with 10 in-person visits to the site at Vancouver General Hospital, totaling approximately 34.5 hours. During these visits, participants will complete a series of questionnaires, sample collections (blood, urine, sputum (clumps of mucus that are coughed up from the lungs)), and lung function tests, in addition to the exposures mentioned above.

Off-site commitments will require participants to follow the recommended diet assigned at the time, complete some electronic questionnaires and breathing tests at home after exposures, and complete telephone calls with the study dietician (approximately 30-minute calls, weekly).

Participants will be provided with meal and grocery deliveries to meet intake goals specified by the study or a subsidized amount of groceries per week depending on the diet intervention assigned at that time.

• Study Type: Interventional
• Enrollment (Estimated): 48
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Agnes Yuen; Phone Number: 66455 604-875-4111; Email: agnes.yuen@ubc.ca
• Study Contact Backup: Name: Agustin Bueso; Phone Number: 21721 604-875-4111; Email: agustin.bueso@ubc.ca

Study Locations

• Canada
  • British Columbia
    • Vancouver, British Columbia, Canada, V5Z 1M9
      • Recruiting
      • University of British Columbia
      • Contact: Agustin Bueso, BSc; Phone Number: 23177 604-875-4111; Email: agustin.bueso@ubc.ca
      • Contact: Agnes CY Yuen, BSc; Phone Number: 66455 604-875-4111; Email: agnes.yuen@ubc.ca

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 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.

Exclusion Criteria:

• 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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Other: Intervention Diet First, then Control Diet; 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; 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.; Other: Control Diet; 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.
Other: Control Diet First, then Intervention Diet; 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; 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.; Other: Control Diet; 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.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
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 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 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 Outcome Measures

Outcome Measure	Measure Description	Time Frame
Within-individual change in blood neutrophil activation and function	Within-individual change in blood 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 sputum biomarkers/arbiters of inflammation	Within-individual change in sputum biomarkers of inflammation (MCP-1, IL-4, IL-5, IL-13, protectins, maresins, resolvins) across Intervention and Control Diet periods post wood smoke exposures.	Across study duration, anticipated ~15 weeks.
Within-individual change in upper airway (nasal) markers of neutrophil activation and function	Within-individual change in biomarkers of neutrophil activation (myeloperoxidase, neutrophil elastase in nasal epithelial lining fluid) across Intervention and Control Diet periods post wood smoke exposures.	Across study duration, anticipated ~15 weeks.
Within-individual change in upper airway (nasal) biomarkers/arbiters of inflammation	Within-individual change in biomarkers of inflammation (including IL-6, IL-8, TNF-alpha, MCP-1, IL-4, IL-5, IL-13, protectins, resolvins, maresins in nasal epithelial lining fluid) across Intervention and Control Diet periods post wood smoke exposures.	Across study duration, anticipated ~15 weeks.
Within-individual change in blood neutrophil %	Within-individual change in blood neutrophil %, compared across Intervention and Control Diet periods post wood smoke exposures.	Across study duration, anticipated ~15 weeks.
Within-individual change in spirometry	Within-individual change in spirometry, as measured by (Forced Expiratory Volume in 1 second (FEV1), Forced Vital Capacity (FVC), and FEV1/FVC) across Intervention and Control Diet periods post wood smoke exposures.	Across study duration, anticipated ~15 weeks.

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Within-individual change in systemic biomarkers/arbiters of inflammation and oxidative stress	Within-individual change in systemic biomarkers/arbiters of inflammation (including IL-6, IL-8, TNF-alpha, MCP-1, IL-4, IL-5, IL-13, resolvins, maresins, protectins in blood) and oxidative stress (including urinary leukotrienes) across Intervention and Control Diet periods post wood smoke exposures.	Across study duration, anticipated ~15 weeks.

Collaborators and Investigators

• Sponsor: University of British Columbia
• Investigators: Principal Investigator: Emily Brigham, MD, University of British Columbia

Study record dates

Study Major Dates

• Study Start (Actual): June 17, 2025
• Primary Completion (Estimated): December 31, 2028
• Study Completion (Estimated): December 31, 2029

Study Registration Dates

• First Submitted: October 18, 2024
• First Submitted That Met QC Criteria: November 26, 2024
• First Posted (Actual): December 2, 2024

Study Record Updates

• Last Update Posted (Actual): February 13, 2026
• Last Update Submitted That Met QC Criteria: February 11, 2026
• Last Verified: May 1, 2025

More Information

Terms related to this study

• Keywords: DHA; Omega-3 fatty acids; EPA; Diet Intervention
• Other Study ID Numbers: H23-03904

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