The study is a randomized, crossover meal-replacement pilot intervention to determine feasibility of a larger scale dietary trial in asthma and gather preliminary evidence for the impact of a healthy diet on asthma outcomes. Participants with doctor-diagnosed asthma were randomized to crossover trial of a 4-week dietary intervention or usual diet with a 4-week washout period. During the dietary intervention, all meals and snacks were provided by the study.
The objective of the study is to demonstrate feasibility of a randomized, controlled clinical trial of a dietary intervention in a population of adults with asthma and to determine sample size estimates for a larger, more definitive trial aimed at improving asthma clinical outcomes and improving markers of inflammation and oxidative stress. The study uses a feeding trial design comprised of a 4 week dietary intervention in which all meals are provided to study participants and a 4 week control diet comprised of usual dietary intake. Participants are randomized to the intervention or control diet and then cross over to the alternate assignment after a 4 week washout period.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
19
Participants were provided meals and snacks for one month that represented a healthy diet that is high in unsaturated fats, approximating a Mediterranean diet
Feasibility as assessed by the number of participant drop outs
Feasibility will be assessed by the number of drop outs.
Time frame: Change from baseline and 4 weeks
Adherence using 24 hour diet recall
Adherence to the dietary intervention will be assessed using self-report of dietary intake via 24 hour dietary recall.
Time frame: Change from baseline to 4 weeks
Adherence assessed by serum carotenoids
Serum carotenoids will be measured at baseline and at 4 weeks. An increase in serum carotenoids is expected with adherence to the dietary intervention.
Time frame: Change from baseline to 4 weeks
FEV1
Spirometry will be measured according to the American Thoracic Society standards. The forced expiratory volume in one second (FEV1) will be assessed and compared between baseline and 4 weeks after the dietary intervention
Time frame: Difference between baseline and 4 weeks
FEV1
Spirometry will be measured according to the American Thoracic Society standards. The forced expiratory volume in one second (FEV1) will be assessed and compared between baseline and 2 weeks after the dietary intervention
Time frame: Difference between baseline and 2 weeks
FVC
Spirometry will be measured according to the American Thoracic Society standards. The forced vital capacity (FVC) will be assessed and compared between baseline and 4 weeks after the dietary intervention
Time frame: Difference between baseline and 2 weeks
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FVC
Spirometry will be measured according to the American Thoracic Society standards. The forced vital capacity (FVC) will be assessed and compared between baseline and 4 weeks after the dietary intervention
Time frame: Difference between baseline and 4 weeks
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 and compared between baseline and 4 weeks after the dietary intervention
Time frame: Difference between baseline and 4 weeks
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 and compared between baseline and 2 weeks after the dietary intervention
Time frame: Difference between baseline and 2 weeks
Asthma status
Asthma Control Test (ACT, range 5-25, higher score denoting better asthma control). The change in score between baseline and week 4 will be assessed.
Time frame: Difference between baseline and 4 weeks
Asthma status
Asthma Control Test (ACT, range 5-25, higher score denoting better asthma control). The change in score between baseline and week 2 will be assessed.
Time frame: Difference between baseline and 2 weeks
Asthma Symptom Utility Index
Asthma Symptom Utility Index (ASUI, range 0-1, higher score denoting fewer symptoms) will be measured and the difference between week 4 and week 0 will be assessed.
Time frame: Difference between baseline and 4 weeks
Asthma Symptom Utility Index
Asthma Symptom Utility Index (ASUI, range 0-1, higher score denoting fewer symptoms) will be measured and the difference between week 2 and week 0 (baseline) will be assessed.
Time frame: Difference between baseline and 2 weeks
Asthma Quality of Life Questionnaire (AQLQ)
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). Scores between week 0 (baseline) and week 4 will be assessed.
Time frame: Difference between baseline and 4 weeks
Asthma Quality of Life Questionnaire (AQLQ)
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). Scores between week 0 (baseline) and week 2 will be assessed.
Time frame: Difference between baseline and 2 weeks
Exhaled nitric oxide
Exhaled nitric oxide is an indicator of airway inflammation and will be measured according to American Thoracic Society standards at baseline and 4 weeks.
Time frame: Difference between baseline and 4 weeks
Exhaled nitric oxide
Exhaled nitric oxide is an indicator of airway inflammation and will be measured according to American Thoracic Society standards at baseline and 2 weeks.
Time frame: Difference between baseline and 2 weeks
Adherence assessed by serum carotenoids
Serum carotenoids will be measured at baseline and at 4 weeks. An increase in serum carotenoids is expected with adherence to the dietary intervention.
Time frame: Difference between baseline and 2 weeks