Effect of a Component of Fish Oil on Exercise-Induced Bronchoconstriction and Airway Inflammation in Asthma

Docosahexaenoic Acid (DHA) as a Nutritional Treatment for Exercise-Induced Bronchoconstriction and Airway Inflammation in Asthma

Docosahexaenoic acid (DHA) is a component of fish oil that is known to support a healthy cardiovascular system, maintain brain function, reduce depression, and improve inflammatory diseases. The study hypothesis is that DHA supplementation will diminish exercise-induced bronchoconstriction and airway inflammation as compared to placebo.

To date, fish oil supplementation studies in patients with asthma have used a combination of omega-3 polyunsaturated fatty acids. A study on the specific formula that is most effective in preventing exercise-induced bronchoconstriction (EIB) has yet to be conducted in humans. Nevertheless, it has been shown that a docosahexaenoic acid (DHA) metabolite, protectin D1, is involved in the active resolution of airway inflammation and that its concentration is greater in healthy control subjects' exhaled breath condensates as compared to patients with asthma during a clinical exacerbation. Supplementing asthmatics with DHA could enable an increased availability of protectin D1 to help resolve airway inflammation during an asthma attack. Furthermore, DHA is known to support a healthy cardiovascular system, maintain brain function, and reduce depression in addition to alleviating inflammatory diseases. Thus, pure DHA supplementation could help patients manage their asthma while providing for their overall health.

The main aim of this study is to determine whether pure DHA can attenuate EIB and airway inflammation in adults with asthma. It is hypothesized that DHA supplementation will diminish EIB and airway inflammation compared to placebo.

Inclusion Criteria:

• Diagnosis of asthma, based on medication use as well as history and symptoms as outlined in the NHLBI Guidelines for the Diagnosis and Management of Asthma
• Diagnosis of EIB, based on a ≥10% fall in FEV1, a measure of lung function, after dry air eucapnic voluntary hyperventilation (EVH), a simulated exercise challenge
• Not currently taking asthma maintenance medication or physician approval to discontinue current asthma medication for the duration of the study
• Not currently taking any fish oil supplements above the level recommended for adequate intake (if currently taking supplements, can participate if the subject stops taking the supplements for 2 weeks before starting the study and throughout the study)
• Agree to limit fish consumption to 1 fish meal per week throughout the study

Exclusion Criteria:

• Post-EVH FEV1 (the amount of air blown out in the first second of a forced exhalation) decreases by more than 50% compared to the subject's resting FEV1 at the first lab testing session
• Pregnancy
• History of cardiovascular disease, including hyperlipidemia (high cholesterol) and hypertension (high blood pressure)
• History of bleeding disorders or delayed clotting time
• History of diabetes
• History of seizures
• Allergy to fish oil
• Allergy to corn or soy products (placebo is a mixture of corn and soy oil)