Sulforaphane (SFN) is a naturally occurring isothiocyanate that is a potent inducer of Phase II enzymes which play a critical role in preventing oxidative stress (via activation of Nrf2). Broccoli sprouts (BS) contain the richest source of SFN.

The main objectives of this study are to test the effect of broccoli sprouts (BS) on biomarkers of oxidative stress (OS), inflammation, basophil activation, and clinical outcomes in mouse allergen-induced asthma by (1) determining if BS improves lung function and airways symptom responses in mouse-sensitized adults with asthma undergoing environmental mouse allergen challenge (EMAC), (2) examining the effect of BS on OS, inflammation, and basophil activation, and (3) examining the effect of BS on changes in OS, inflammation, and basophil activation after EMAC.

After eligibility is confirmed, participants will be randomized to (a) placebo then BS or (b) BS then placebo. At randomization, baseline exhaled nitric oxide (eNO), forced expiratory volume at one second (FEV1), nasal epithelial gene expression, urinary OS biomarkers, serum inflammatory and OS biomarkers, and basophil activation will be assessed. These will be assessed again after 7 days on the assigned intervention at two time points: pre- and post-EMAC. The 1 week time period was chosen because previous studies have shown that daily ingestion of a broccoli sprout homogenate for three days resulted in upregulation of phase II enzyme gene expression in nasal epithelial cells. Following a 2-week washout period, this protocol will be repeated for the second intervention, phase II. The 2 week washout period will be sufficient as the half life of the extract of the active ingredient in broccoli sprouts, SFN, has been shown to be 1.8 hours.(16) Participants' diets will be assessed before and after each intervention with a Food Frequency Questionnaire and a questionnaire to capture intake of specific foods that are rich in SFN.

Inclusion Criteria:

• Age 18-49 years
• Physician-diagnosed asthma
• No other major pulmonary disease such as cystic fibrosis or chronic obstructive pulmonary disease (COPD)
• Mouse sensitization, defined by a positive skin prick test to mouse epithelial extract or positive mouse-specific immunoglobulin E (IgE)
• Non-smoker

Exclusion Criteria:

• Severe or unstable asthma defined as requiring hospitalization in the previous year or intubation in the previous 2 years, or on high-dose inhaled corticosteroids or chronic oral corticosteroids
• Baseline FEV1 and FEV1/forced vital capacity (FVC) < 70% predicted
• Positive skin prick test (SPT) to a pet currently living in the participant's home
• Other significant medical issues such as heart disease or poorly controlled hypertension, or hypothyroidism
• Pregnancy or nursing/breastfeeding mothers
• On beta-blocker therapy
• Taking anti-oxidant supplements
• Unable to stop antihistamines prior to skin testing
• Unable to stop medications that may interfere with allergen challenge responses prior to challenges.
• The participant has food allergy to BS or AS.
• Omalizumab use within the last 12 months.
• Oral corticosteroid use within the last 2 weeks.