Food allergy affects up to 10% of the population. The mainstay of management involves dietary avoidance and provision of rescue medication in the event of an accidental reaction. The Integrated approaches to food allergen and allergy management (iFAAM) collaboration is an EU-funded academic/clinical/industry consortium with the aim to improve allergen risk management including food labelling. Much of this work requires the validation of the minimum 'eliciting dose' for the food-allergic population and how this can be translated into risk management.

A number of studies (including iFAAM and the TRACE study - NCT01429896) have assessed the eliciting dose for peanut allergic patients, using food challenges where peanut-allergic individuals are eat incremental doses of peanut under strict medical supervision.

In this extension study, peanut-allergic subjects will have undergone (in a cross-over manner) three double-blind, placebo-controlled food challenges to peanut:

1. incremental doses of peanut in a water-continuous matrix;
2. incremental doses of peanut baked into a cookie biscuit;
3. a single dose of peanut in a water-continuous matrix.

The differences in eliciting dose, symptom pattern and underlying physiological mechanisms will provide essential data on how the presentation and consumption of peanut affects the amount needed to trigger an allergic reaction, to inform industry and food regulators as to how to best protect the food-allergic population.

Inclusion Criteria:

• Written informed consent.
• Male and female participants in the TRACE study (NCT01429896) who are 18-45 years of age at the time of entry to the TRACE study (Visit 1) and had a positive DBPCFC to peanut at baseline (Visit 1).

Exclusion criteria

• unable to comply with study procedures

De-identified data will be made public through the Integrated approaches to food allergen and allergy management (iFAAM) collaboration