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

Not Applicable

Not yet recruiting

• Conditions: Healthy Individuals

• Registration Number: NCT06711614
• Lead Sponsor: University of British Columbia

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.

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 Timeline

• Status Verified: 2024-07
• Study First Submitted: 2024-10-18
• Study First Submitted QC: 2024-11-26
• Study First Posted: 2024-12-02
• Last Update Submitted: 2025-01-16
• Last Update Posted: 2025-01-20
• Study Start: 2025-02-28
• Primary Completion: 2027-08-31
• Study Completion: 2029-12-31

Recruitment & Eligibility

• Status: NOT_YET_RECRUITING
• Sex: All
• Target Recruitment: 48

Inclusion Criteria

• Healthy, with no history of respiratory disease specifically.
• No active medication or unprescribed supplement use, or willing to abstain from supplement use for 4 weeks prior to the study start and for the entire 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.
• 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 & Design

• Study Type: INTERVENTIONAL
• Study Design: CROSSOVER

Primary Outcome Measures

Name	Time	Method
Within-individual change in sputum neutrophil %	Across study duration, anticipated ~15 weeks.	Within-individual change in sputum neutrophil %, compared across Intervention and Control Diet periods post wood smoke exposures.
Within-individual change in sputum neutrophil activation and function	Across study duration, anticipated ~15 weeks	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.
Within-individual change in airway resistance	Across study duration, anticipated ~15 weeks.	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.
Within-individual change in sputum biomarkers of inflammation	Across study duration, anticipated ~15 weeks.	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.

Secondary Outcome Measures

Name	Time	Method
Within-individual change in sputum biomarkers/arbiters of inflammation	Across study duration, anticipated ~15 weeks.	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.
Within-individual change in upper airway (nasal) markers of neutrophil activation and function	Across study duration, anticipated ~15 weeks.	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.
Within-individual change in upper airway (nasal) biomarkers/arbiters of inflammation	Across study duration, anticipated ~15 weeks.	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.
Within-individual change in blood neutrophil %	Across study duration, anticipated ~15 weeks.	Within-individual change in blood neutrophil %, compared across Intervention and Control Diet periods post wood smoke exposures.
Within-individual change in blood neutrophil activation and function	Across study duration, anticipated ~15 weeks	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.
Within-individual change in spirometry	Across study duration, anticipated ~15 weeks.	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.

Trial Locations

Locations (1)

University of British Columbia; 🇨🇦 Vancouver, British Columbia, Canada