There isn’t substantial scientific evidence to support that eggs, milk, or fish have a stimulating effect on increasing mucus in children with chest infections.

However, individual sensitivities or allergies to certain foods can exacerbate respiratory symptoms in some children.

One blinded trial found that a dairy-free diet was associated with a significant reduction in self-reported levels of nasopharyngeal secretions in adults who previously complained of persistent nasopharyngeal mucus hypersecretion. Frosh, A., Cruz, C., Wellsted, D. and Stephens, J. (2019), Effect of a dairy diet on nasopharyngeal mucus secretion. The Laryngoscope, 129: 13-17. https://doi.org/10.1002/lary.27287