This research is being done to evaluate the feasibility of a prudent versus Western diet feeding study in women with asthma in Baltimore City. The results of this research will provide data to appropriately design a definitive study looking at the differential effects of these two diets on asthma health.
The investigators are interested in the effects of two different diets on asthma health. The first, a prudent diet, consists of a high intake of fruits and vegetables, whole grains, fiber, omega-3 fatty acids, low-fat dairy products, and overall high levels of antioxidants (which may protect the lungs and the body against inflammation in patients with asthma). The second, a Western diet, consists of a high intake of processed foods, fast foods, sweets, omega-6 fatty acids, and a low intake of fiber (which may promote inflammation in the lungs and the body of patients with asthma). This pilot study will test the feasibility/acceptability of the study design in providing these two diets to participants over a short period of time (6 days per diet), and gather preliminary data on asthma health outcomes that will be used to design a larger, definitive trial. Each participant will be randomly (by chance, like flipping a coin) assigned to start with one of these diets. All foods in each of the diets will be supplied by the study, and participants will be expected to eat all of the food provided and only the food provided for the next 6 days. The investigators will make sure that each participant gets enough food for what their body needs, based on a visit with a nutritionist at the beginning of the study. After eating either the Prudent diet or Western diet for 6 days, participants will have a 4-8 week break (or washout period), during which they will eat their usual diet. Then participants will begin the alternate dietary intervention (Prudent or Western) for another 6 days, depending on which they received first. Before and after each dietary period, researchers will ask questions, check lung function, and collect samples from participants to determine acceptability of the meals and study design, gather feedback on the intervention and overall study structure, assess for changes in lung health and asthma control, measure inflammation and oxidative stress in the lungs and systemic circulation, and evaluate changes in the airway and gut microbiome associated with the interventions that may influence the asthmatic response.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
DOUBLE
Enrollment
3
Six days of meals provided with high amounts of fruits and vegetables, whole grains, fiber, omega-3 fatty acids, low-fat dairy products, and overall high levels of antioxidants.
Six days of meals provided with high amounts of processed foods, fast foods, sweets, omega-6 fatty acids, and a low intake of fiber.
Johns Hopkins University
Baltimore, Maryland, United States
Feasibility: participant feedback
We will measure this via questionnaire at the final study visit.
Time frame: At conclusion of second feeding period, 7-14 weeks post-enrollment
Feasibility: adherence to diet
Daily adherence diaries completed by each participant during each dietary intervention.
Time frame: Completed daily during each of the two, 6-day feeding periods.
Feasibility: serum carotenoids
Serum carotenoids will be measured the morning prior to initiating each feeding period and the morning following completion of each 6-day feeding period.
Time frame: Difference between day 1 and day 7 of each feeding period
Feasibility: serum lipids
Serum lipids will be measured the morning prior to initiating each feeding period and the morning following completion of each 6-day feeding period.
Time frame: Difference between day 1 and day 7 of each feeding period
Feasibility: serum free fatty acids
Serum free fatty acids will be measured the morning prior to initiating each feeding period and the morning following completion of each 6-day feeding period.
Time frame: Difference between day 1 and day 7 of each feeding period
Feasibility: obtaining sputum samples
Induced sputum will be collected for analysis of airway inflammation, a proposed key outcome for a definitive future trial.
Time frame: Difference between baseline levels and levels on day 7 of each feeding period.
Asthma Quality of Life Questionnaire (AQLQ)
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Asthma Quality of Life Questionnaire (AQLQ) is a 32 item questionnaire and each question uses a 7-point Likert scale (7 = not impaired at all - 1 = severely impaired).
Time frame: Difference between baseline levels and levels on day 7 of each feeding period.
Asthma Symptom Utility Index (ASUI)
Asthma Symptom Utility Index (ASUI, range 0-1, higher score denoting fewer symptoms) will be measured.
Time frame: Difference between day 1 and day 7 of each feeding period
Asthma Control Test (ACT)
Asthma Control Test (ACT, range 5-25, higher score denoting better asthma control).
Time frame: Difference between baseline levels and levels on day 7 of each feeding period.
Daily symptoms
Daily symptom diaries completed by each participant during each dietary intervention.
Time frame: Completed daily during each of the two, 6-day feeding periods.
FEV1
Spirometry will be measured according to the American Thoracic Society standards. The forced expiratory volume in one second (FEV1) will be assessed.
Time frame: Difference between day 1 and day 7 of each feeding period
FVC
Spirometry will be measured according to the American Thoracic Society standards. The forced vital capacity (FVC) will be assessed.
Time frame: Difference between day 1 and day 7 of each feeding period
FEV1/FVC ratio
Spirometry will be measured according to the American Thoracic Society standards. The forced expiratory volume in one second (FEV1)/forced vital capacity (FVC) ratio will be assessed.
Time frame: Difference between day 1 and day 7 of each feeding period
Albuterol inhaler (rescue medication) use
Daily diaries of self-reported albuterol use completed by each participant during each dietary intervention.
Time frame: Completed daily during each of the two, 6-day feeding periods.
Exhaled nitric oxide
Exhaled nitric oxide is an indicator of airway inflammation and will be measured according to American Thoracic Society standards.
Time frame: Difference between day 1 and day 7 of each feeding period.
Markers of systemic Th2 inflammation
Serum and urine will be assessed for markers of Th2 inflammation.
Time frame: Difference between day 1 and day 7 of each feeding period.
Markers of airway Th2 inflammation
Sputum will be assessed for markers of Th2 inflammation.
Time frame: Difference between baseline levels and levels on day 7 of each feeding period.
Markers of systemic Th1 inflammation
Serum will be assessed for markers of Th1 inflammation.
Time frame: Difference between day 1 and day 7 of each feeding period.
Markers of airway Th1 inflammation
Sputum will be assessed for markers of Th1 inflammation.
Time frame: Difference between baseline levels and levels on day 7 of each feeding period.
Markers of systemic oxidative stress
Serum and urine will be assessed for markers of oxidative stress.
Time frame: Difference between day 1 and day 7 of each feeding period.
Markers of airway oxidative stress
Sputum will be assessed for markers of oxidative stress.
Time frame: Difference between baseline levels and levels on day 7 of each feeding period.
Upper airway microbiome
Microbiome assessment via nasal swab collection.
Time frame: Difference between microbial community composition on day 1 and day 7 of each feeding period.
Lower airway microbiome
Microbiome assessment via sputum collection.
Time frame: Difference in microbial community composition between baseline and day 7 of each feeding period.
Gut microbiome
Microbiome assessment via stool collection.
Time frame: Difference between microbial community composition on day 1 and day 7 of each feeding period.