AbstractBackgroundDietary fibre may reduce the risk of allergy. Our aim was to investigate the association between fibre intake in childhood, asthma, allergic rhinitis and IgE sensitization up to adulthood.MethodsThe individual fibre intake of 2285 participants from the Swedish population‐based birth cohort BAMSE was estimated between 98‐ and 107‐item food frequency questionnaires at ages 8 and 16 years, respectively. At 8, 16 and 24 years, asthma and allergic rhinitis symptoms were assessed by questionnaires, and sensitization to common allergens by serum IgE. Longitudinal associations were analysed by generalized estimating equations, adjusting for potential confounders.ResultsAn inverse overall association was indicated between fibre intake at 8 years and allergic rhinitis symptoms up to 24 years (OR per 5 g/d 0.86; 95% CI 0.77–0.96), particularly in combination with airborne (0.74; 0.62–0.89) and food (0.69; 0.54–0.88) allergen sensitization. Higher fibre intake was also associated with specific allergen sensitization, for example, birch (0.77; 0.67–0.88) and soy (0.68; 0.53–0.87). No association was observed with asthma. Regarding sources, fruit (0.79; 0.67–0.94) and other (potatoes, chips/popcorn, legumes, and nuts, 0.71; 0.50–0.99), but not cereal or vegetable fibre were associated with allergic rhinitis. In additional analyses, including long‐term fibre intake at 8 and 16 years, excluding participants with food‐related allergic symptoms to examine reverse causation, as well as adjusting for antioxidant intake, associations were attenuated and became non‐significant.ConclusionHigher fibre intake in mid‐childhood may be inversely associated with allergic rhinitis and sensitization to specific allergens up to adulthood. However, avoidance of food triggers of allergic symptoms in allergic rhinitis patients may contribute to the protective associations.