Dietary Interventions in Asthma Treatment: Sprouts Study

Overview

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.