Fatty Acids in Airway Smooth Muscle of Asthmatics

In this proof of concept study, the investigators aim to determine if supplementation with coconut oil causes an increase in cholecystokinin and cholecystokinin receptor expression in the airway smooth muscle of lean asthmatics, and whether these changes correlate with changes in airway stiffness (estimated by bronchodilator reversibility, airway reactivity, and airway resistance) or symptom control. The investigators propose a 5 week, single center trial in 20 lean patients with mild asthma (not taking inhaled corticosteroids) aged 18 and older. Subjects will supplement their usual diets with 3 tablespoons of coconut oil, a commercially available oil with high dodecanoic acid content, for 3 weeks. To quantify changes in airway smooth muscle cholecystokinin and cholecystokinin-receptor expression, each subject will undergo bronchoscopy with endobronchial biopsies before and after coconut oil ingestion. For the secondary analysis, subjects will also complete spirometry with bronchodilator testing, methacholine challenge, body plethysmography, and an Asthma Control Questionnaire (ACQ) before and after the dietary intervention. This information will be used to compare the changes in airway smooth muscle cholecystokinin and cholecystokinin receptor expression to changes in bronchodilator reversibility, airway reactivity, airway resistance, and symptom control. In the exploratory aims, the investigators will correlate the changes in airway smooth muscle cholecystokinin and cholecystokinin receptor expression with changes in FEV1 and peak flow measurements. The investigators therefore hope to elucidate information about the mechanistic role of cholecystokinin in airway smooth muscle stiffness and contraction.