Baked Egg Goods without Wheat Flour Carry an Increased Risk of Reaction

Rationale: Eating egg protein in baked form has been shown to hasten outgrowing of an egg allergy. Baking egg with wheat flour decreases in vitro antigenic activity to heat-resistant ovomucoid. This is believed to be due to the “matrix effect,” wherein the sequential epitope is polymerized and forms high-molecular weight complexes. To study the matrix effect and the importance of wheat flour on baked egg tolerance in vivo, we examined the outcomes of OFCs to baked egg in egg allergic children.

Methods: A 2-year retrospective chart review was performed in 104 egg allergic children, ages 0.9 to 16.8 y (mean 5.7 y), who were sensitized to egg by skin test and/or specific IgE and who underwent OFCs to baked egg. The effect of wheat flour or a wheat replacer (rice flour) on OFCs to baked egg in a standardized muffin (2.2 g of egg protein) was assessed.

Results: Eighty-nine (85.6%) children were challenged with a muffin baked with wheat flour. Fifteen (14.4%) received a muffin containing wheat replacer. Overall, 68 (65.4%) children passed and 36 (34.6%) failed OFCs to baked egg. In the wheat group, only 30.3% (27/89) failed, while 60% (9/15) of the non-wheat group failed OFCs to baked egg. Females comprised only 37% of the cohort. After adjusting for age, gender, and history of atopic dermatitis, the odds ratio of failing an OFC to baked egg with a muffin containing wheat replacer was 5.3 (95% CI 1.54,18.2; p=0.0083) compared to a muffin containing wheat flour.

Conclusions: Children undergoing OFCs to egg in baked goods made with wheat replacer may be at an increased risk for failing an OFC. Wheat replacers should only be used when clinically indicated, as in wheat allergic children. Children who pass a baked egg OFC using a muffin made with wheat flour should be warned that they might be at risk for reacting to baked egg products made without wheat.