Impact of Chewing Gum on FeNO Levels in Patients With Bronchial Asthma

FeNO measurement is a non-invasive, available measure both for the diagnostic workup of patients with suspected bronchial asthma and for therapy management after a confirmed diagnosis. In patients with bronchial asthma, FeNO is a biomarker of airway inflammation. The recommended lower FeNO limits of the American Thoracic Society (ATS) are < 25 ppb in adults. A significantly elevated FeNO level (≥ 50 ppb), especially in the presence of increased blood eosinophil counts (≥ 300/µl), indicates an increased risk of exacerbation. Furthermore, patients with elevated FeNO levels are generally (inhalative cortison treatment; ICS) responsive. Conversely, elevated FeNO levels (especially FeNO levels > 50 ppb) during ICS therapy, despite clinical stability, argue against a reduction in the ICS dose.

Elevated FeNO levels during ICS therapy can occur due to poor treatment adherence. However, persistently elevated FeNO levels despite ICS therapy can also indicate inflammation in the airways that does not respond to further increases in the ICS dose. In summary, measuring airway inflammation using FeNO is an important component in the diagnosis and management of asthma.

It is already known that acute tobacco smoke exposure lowers FeNO levels in patients with asthma. Furthermore, FeNO levels are strongly influenced by factors such as infections, stress, or exposure to pollutants. Food containing nitrates (salad, sausage) can increase FeNO levels. Our patients are informed about these known factors so that they can avoid exposure prior to their medical consultation and examination. Conversely, it is suspected that chewing gum, which influences the oral flora, may lower FeNO levels, which would lead to false-negative FeNO levels and thus potentially prevent better diagnosis and treatment of asthma. However, to the best of our knowledge no study has yet examined the influence of chewing gum on FeNO levels.

Hence, the aim of the study is to investigate the influence of chewing gum consumption on FeNO levels in asthma patients in order to avoid systematic errors in treatment decisions.

Patients admitted to our outpatient clinic for bronchial asthma undergo regular FeNO measurements. If the value is ≥ 25 ppb (elevated), the patients are randomized into two groups after obtaining their consent. In the control group, a FeNO measurement is performed again after 15 minutes. In the second group, the FeNO measurement is measured again after 15 minutes of consuming sugar-free, antioxidant-containing chewing gum. The following data are then collected and documented from the patients: age, gender, height, weight, smoking status, current medication, other illnesses, whole body lung function test, and laboratory tests (eosinophils, IgE). Participation in the study will not change the course of the patient's stay in our clinic.