DASH Dietary Intervention Program Promises "Modest but Potentially Clinically Significant" Benefits and a High Rate of Satisfaction in Adults with Uncontrolled Asthma

After 6 months, an intervention program based on the Dietary Approaches to Stop Hypertension (DASH) diet increased the proportion of participants with uncontrolled asthma who achieved minimal clinically important improvement in asthma control.

Dietary factors have been implicated in the recent global increase in asthma cases, and the Mediterranean diet has been shown in cohort studies to reduce asthma symptoms and increase asthma control. The Dietary Approaches to Stop Hypertension (DASH) diet is a pattern of healthy eating similar to the Mediterranean diet.

The DASH diet is based on a high intake of fruit, vegetables, low-fat dairy, whole grains, nuts, seeds, and beans, as well as on low consumption of fat, sodium, and added sugars and on moderate drinking.

The US Department of Agriculture has recommended the DASH diet because of its proven ability to prevent or control high blood pressure.

However, similar evidence for the diet’s ability to improve asthma control was not available until the DASH for Asthma trial. This pilot trial compared patient outcomes after usual care with outcomes after participation in a structured intervention program that promoted smoking cessation as well as dietary changes.

DASH for Asthma was a 6-month, controlled trial in 90 patients with uncontrolled asthma and a low-quality diet at baseline who were recruited from Kaiser Permanente medical centers in San Francisco and Hayward, CA; 46 of these patients were randomly assigned to participate in the DASH intervention.

The intervention began with a 3-month intensive stage that included three individual and eight group coaching sessions that focused on diet and behavior modifications. The initial stage was followed by a 3-month maintenance stage that used telephone consultations.

The intervention was based on a comprehensive manual that included lifestyle coaching scripts, participant handouts, and action planning and tracking worksheets based on the DASH principles outlined in the US 2010 Dietary Guidelines. Participants received a binder to which handouts, worksheets, and home-activity checklists were added during each successive session. Keeping a food diary was an important component of the program.

The DASH for Asthma pilot study found that after 6 months of participation in the intervention, the quality of the participants’ diet improved, and the proportion of participants who achieved minimal clinically important improvement in asthma control increased.

Although these improvements were modest, the investigators noted they were “potentially clinically significant” and concluded that a full-scale trial to determine the efficacy of the DASH intervention for uncontrolled asthma is warranted.

In a study of responses to surveys taken after the trial’s intervention sessions, participants and coaches were found to be highly satisfied with the intervention’s individual and group sessions.

Important contributors to satisfaction and self-efficacy included:

  • Mastery of knowledge and skills like awareness, goal setting, self-monitoring, and problem solving
  • Social learning by sharing experiences and ideas with other participants
  • Good coaching skills including reflective listening, empathy, and motivational counselling

Participants valued the personalized feedback received in individualized sessions, and coaches valued participant engagement because it made sessions more effective. Food tasting helped to engage participants and provided an opportunity for observational learning.

Because of the high rate of class attendance and of self-monitoring during the intervention, the investigators concluded that participants were highly engaged in the program. They also concluded that “The DASH behavioral intervention was feasible and highly acceptable to participants with uncontrolled asthma.”