Natural supplement astaxanthin tested as new asthma aid in dirty air

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Adults 18+ y * Confirmed clinical diagnosis of mild-to-moderate asthma, defined as: * A physician diagnosed asthma condition consistent with BTS/NICE/SIGN (2024) * Asthma managed at GINA (2024) step 1-3 therapy level, with stable maintenance treatment for ≥4 weeks prior to enrolment * No asthma exacerbation requiring systemic corticosteroids within the preceding 6-8 weeks (those with suspected Asthma will be invited to a familiarisation and eligibility session where they will have clinical investigations to assess for asthma and thus be included or excluded) * Ability to demonstrate acceptable and repeatable spirometry in accordance with ATS/ERS standards * Willing to refrain from antioxidant and anti-inflammatory supplementation (e.g. Omega-3, turmeric, NSAID supplements) for the duration of the study * Not consuming high dietary ASTX sources (e.g., frequent salmonid or crustacean intake), assessed at screening * non-smoking and non-vaping * Able and willing to take daily study capsules and attend all required visits * Able and willing to complete home monitoring, including peak flow, air-quality monitoring, and questionnaires * Able to provide written informed consent Exclusion Criteria: * Current smokers or vapers which is associated with chronic airway remodelling, reduce hyperresponsiveness to bronchodilators, and increased neutrophilic inflammation, which can obscure the true effects of asthma-target interventions * Respiratory tract infection within the preceding 4 weeks * Pregnant or lactating individuals * Presence of significant co-morbidities, including CVD or autoimmune or systemic inflammatory diseases * Renal or gastrointestinal disorders that may affect astaxanthin absorption and metabolism * Known allergy or hypersensitivity to ASTX or any components of the study supplement * History of current evidence of alcohol or substance abuse * Participation in another interventional drug or supplement study within the preceding 3 months * Use of medicines with a narrow therapeutic index where supplement interactions may pose risk (e.g., ciclosporin/tacrolimus, warfarin), assessed by investigator * Other significant chronic respiratory disease (e.g., COPD, bronchiectasis)