Adult-onset asthma, allergy, and aspirin hypersensitivity associate with self-reported food avoidance

Background: The adoption of avoidance diets by adult-onset asthmatics has not previously been studied. We hypothesized that avoidance diets would associate with adult-onset asthma, allergy, and aspirin-exacerbated respiratory disease (AERD). Methods: A total of 1247 subjects with adult-onset asthma (age range: 31–91) from the Finnish national registry, and age- and sex-matched controls (n = 1970) participated in a questionnaire study in 1997. We estimated the association between asthma/allergy/AERD and avoidance diets, adjusting for potential confounding factors and validated the results in two retrospective cohorts of 5080 rhinitis/rhinosinusitis patients and 167 AERD patients from 2019 to 2020. Results: The presence of asthma positively associated with adoption of any avoidance diet (adjusted OR [CI95%] 1.24 [1.02–1.51], p = 0.029) as did allergic disease and self-reported AERD within the asthmatic group (1.79 [1.29–2.48], p = 0.001 and 1.69 [1.15–2.49], p = 0.007, respectively). Asthmatics and allergic asthmatics were more likely to report avoidance of fish, fruits and vegetables, and spices (p ≤ 0.03) compared to controls and non-allergic asthmatics. The adjusted OR for multiple diets among AERD patients was 2.57 [1.34–4.95] p = 0.005. In the validation, 26.2% of the allergic asthmatics and 10.8% of AERD patients had documented avoidance diets. Conclusions: Our study shows a positive association between avoidance diets and adult-onset asthma, and with allergic disease or AERD within asthmatic patients. Although we lack information on the reason patients chose to observe a specific diet, our results reinforce the importance of asking patients about their diet and if needed, giving dietary advice for adult asthma patients to help them avoid the adoption of unnecessarily restrictive diets.