We thank our study participants, who were recruited through the TRACE Peanut study (funded by the UK Food Standards Agency); we are grateful to the study investigators (Chief investigator A Clark) and the Food Standards Agency for their support; and to the members of our Data Safety Monitoring Board: Professor Stephen Till, Dr Hazel Gowland and Dr Mich Erlewyn-Lajeunesse. We are grateful to Emily Wilson, Louise Cross and staff at the Respiratory Clinical Research Facility at the Royal Brompton Hospital for their clinical support.