The DASH Diet for Adults With Uncontrolled Asthma

Dietary intervention efficacy trials are distinctly lacking in asthma research. This pilot
study aims to provide effect size estimates and justification, clinical trial and
intervention feasibility data, and procedural materials for a full-scale randomized
controlled trial that will determine the efficacy and mechanisms of action of the Dietary
Approaches to Stop Hypertension (DASH)—a recommended dietary pattern based on proven
cardiovascular benefits—as adjunct therapy to standard care for adults with uncontrolled
asthma. Eligible, consenting participants (n=90) will be randomized to receive usual care
alone or combined with a DASH intervention. Follow-up assessments will occur at 3 and 6
months. By evaluating a dietary pattern approach to improving asthma control, this study
could advance the evidence base for refining clinical guidelines and public health
recommendations regarding the role of dietary modifications in asthma management.

Inclusion Criteria:

- Ethnicity: All ethnic groups

- Body mass index (BMI) 18.5-39.9 kg/m2

- Suboptimally controlled asthma:

- Diagnosis of asthma on the current medical problem list

- Currently prescribed at least 1 medication for the treatment of asthma

- Physiological evidence of asthma with demonstrable reversibility of airway
obstruction, or a specialist's confirmation of asthma diagnosis based on chart review

- Documented history of high asthma-related emergency and/or inpatient encounters or
reliever medication usage

- Asthma Control Test: total score <20 or item score <3 for any of the first 4
questions regarding symptoms (3-6x/week or more), nighttime awakening (1x/week or
more), interference with normal activity (at least some of the time), and rescue
medication use for symptom relief (2-3x/week or more)

- Kaiser member for ≥1 year

- PCP approval of study screening

- Able and willing to enroll and provide written informed consent

Exclusion Criteria:

- Intermittent asthma, defined as either seasonal asthma or (daytime asthma symptoms
<2x/week and nocturnal symptoms <2x/month and no use of long-term control
medications)

- Primary diagnosis of COPD (emphysema or chronic bronchitis) on the current medical
problem list or suggested by baseline spirometry and smoking history

- Previous diabetes (other than during pregnancy) or diabetes diagnosed as a result of
fasting blood glucose or hemoglobin A1c levels obtained at screening

- Previous cardiovascular disease: e.g., coronary heart disease, cerebrovascular
disease, peripheral vascular disease, heart failure, or aortic aneurysm

- Diagnosis of cancer (other than non-melanoma skin cancer) that is/was active or
treated with radiation or chemotherapy within the past 2 years

- Inflammatory bowel disease, colostomy, malabsorption, or major gastrointestinal
resection

- Diagnosis of bipolar or psychotic disorder or hospitalization for psychological or
emotional problems within the last 2 years

- Diagnosis of a terminal illness and/or in hospice care

- Fasting LDL cholesterol >190 mg/dL, triglycerides >500 mg/dl, fasting blood glucose
>125 mg/dl

- Significant liver enzyme abnormality as indicated by AST or ALT more than 2 times the
upper limit of normal or a clinical diagnosis of hepatitis

- Renal insufficiency (GFR<60 ml/min)

- Current use of insulin or oral hypoglycemic agents

- Use of oral corticosteroids >5 days/month on average

- Current use of medications for treatment of psychosis or manic-depressive illness

- Current use of prescription or non-prescription weight-loss products or any
dietary/herbal supplements and unwillingness to discontinue;

- Inability to speak, read, or understand English at the 6th-grade level or above

- Inability to perform pulmonary function tests by spirometry in a consistent manner

- DASH concordance index >60%

- Unwillingness to modify current diet

- Current or planned participation in a structured program that overtly focuses on diet
and nutrition

- Planning to undergo bariatric surgery during the study period

- Actively attempting to lose weight, or weight change >15 lbs during prior 3 months

- Consumption of >21 alcoholic drinks per week, or >=6 drinks on one occasion twice or
more per week, or alcoholism as determined by the Alcohol Use Disorders
Identification Test

- Pregnant, lactating, or planning to become pregnant during the study period

- No longer a Kaiser patient or planning to transfer care out of Kaiser or to move out
of the area during the study period

- Family/household member of another study participant or of a study staff member

- Enrolled or planning to enroll in another research study that would limit full
participation in the study or confound the interpretation of the study's findings

- Investigator discretion for safety or protocol adherence reasons