AbstractBackgroundThere is no clear explanation for the large variation in threshold levels among peanut‐allergic children. We hypothesized that diet composition can partly explain this variation in thresholds, as nutrients and foods influence the intestinal barrier function and microbiota.Aimto explore the relationship between the threshold levels for peanut and nutritional intake and gut microbial composition in peanut‐allergic children.MethodsIn this explorative cross‐sectional study the cumulative threshold levels for peanut were determined by oral food challenge tests. Data on nutrients and foods consumed were obtained from 3‐day food diaries. Microbial composition of faeces and saliva were determined by molecular microbiota detection technique. Multivariable linear regression analysis and multiple logistic regression were used to explore the associations, adjusted for energy and senitization.ResultsSixty‐five children were included, of whom 32 (49%) (median age 50 months, IQR 28.0–96.5) had a positive oral food challenge. Significant positive associations were found between the intake of total carbohydrates, vitamin A and cumulative threshold levels for peanut, while significant negative associations were found for long‐chain polyunsaturated fatty acids, linoleic acid and omega‐6 fatty acids. No associations were found between threshold levels and microbial composition of faeces and saliva. However, a significant higher abundance of Proteobacteria and Bacteroidetes in saliva (p= 0.011 and 0.04, respectively) and of Proteobacteria in faeces (p= 0.003) were found in children with a positive peanut challenge compared to children with a negative peanut challenge.ConclusionAs a novel concept, this study showed that dietary composition is related to threshold levels for peanut.