Funding completion date passed, inadequate enrollment

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.

Inclusion criteria:

• Age 18-55

• Female

• Obese (BMI>30kg/m2)

• Not breastfeeding

• Diagnosis of asthma, defined as

  • Physician diagnosis of asthma, and
  • Current treatment for asthma by a healthcare provider within the preceding twelve months. (Current asthma treatment defined as regular use of asthma medications. Asthma medications include short and long acting adrenergic bronchodilators, bronchodilator combinations, inhaled anticholinergics, inhaled corticosteroids, cromolyn sodium and nedocromil, leukotriene modifiers and methylxanthines.)

• Stable asthma, defined by no asthma exacerbation (ED visit, course of increased systemic steroids, or urgent health care visit for asthma) during the prior four weeks.

• Symptomatic asthma (Asthma Control Test <20 at baseline screening visit)

• Non-smoker, defined by no cigarettes in the past year and a negative urine cotinine

• No other major pulmonary disease such as cystic fibrosis or chronic obstructive pulmonary disease

• Willing to eat study diet and nothing else for each of the 6 days of controlled feeding

Exclusion criteria:

• Chronic oral steroid therapy (daily)
• Oral corticosteroid use within the past 4 weeks
• Respiratory tract infection within the past 4 weeks
• Significant medical issues such as heart disease or poorly controlled hypertension, type 1 diabetes, poorly controlled type 2 diabetes, or hypothyroidism that would interfere with collection of outcome measures or present safety issues in the opinion of the Principal Investigator
• Pregnancy (self-report), planning a pregnancy, or nursing/breastfeeding mothers
• Food allergy that interferes with ability to complete the study
• Food preferences, intolerances, or dietary requirements that would interfere with diet adherence
• Taking vitamin supplements
• Planned dietary changes during the study period
• Use of coumadin
• Consumption of more than 14 alcoholic drinks per week, or consumption of 6 or more drinks on an occasion, one or more occasions per week
• Forced expiratory volume at one second (FEV1)<1.5 liters or <60% predicted
• Inability to perform acceptable spirometry
• Any condition or compliance issue which in the opinion of the investigator might interfere with participation in the study
• Lack of appropriate food refrigeration and preparation equipment (oven or microwave)
• Inability to produce adequate sputum following induction with hypertonic saline neb

Participants and nutrition staff will be aware of randomization assignments. All other study staff and the investigators will be blinded to assignment during the study.