IGHE and asthma: In addition, asthmatic subjects with IgE reactivity to birch pollen more frequently report gastrointestinal symptoms compared to birch pollen sensitized subjects without asthma during the spring (5.7 % vs 0.8 %, p = 0.034), summer (4.2 % vs 0.0 %, p = 0.026) and autumn (3.7 % vs 0.0 %, p = 0.046) (Fig. 4 and Additional file 2: Table S1).