The Effect of Extrinsic Factors on Food Allergy (Ex-Factor)

Food allergy is a common problem, affecting 5-8% of the population. Peanut allergy causes reduced quality of life due to the perceived high risk of severe reactions. Patients rely on accurate labeling of both loose and pre-packed foods, but these are often ambiguous and unhelpful. There is a common conception that labeling is 'over-cautious'. Peanut-allergic consumers face increasingly restricted food choices in complying with this advice due, in part, to the proliferation of advisory labels such as 'may contain peanuts'. This contributes to the reduces quality of life of affected individuals.

For industry to provide more accurate and helpful labeling, certain characteristics of the food-allergic population need to be defined. Firstly, the minimum 'eliciting dose' for the population has been estimated by studying large groups of peanut allergic patients who are challenged with peanut ingestion in increasing amounts. From these, an eliciting dose that provokes a reaction in 10% of the food-allergic population has been estimated at between six and 14mg of peanut protein.

Translation of population eliciting doses (ED) into acceptable levels of allergen contamination for the population requires consideration of a 'safety factor'- to account for individual variability in dose threshold and severity. Data suggest such variability depends in part on extrinsic factors (exercise and sleep restriction). Each factor may have a different effect in scale and direction. The investigators are proposing a cross-over trial with 85 peanut-allergic adults who will each undergoing a baseline peanut challenge followed by repeat challenges with extrinsic factors applied, in random order (repeat baseline, +exercise and +sleep restriction). These data will further define ED for the UK population and a safety factor derived from shift in threshold, to inform industry and protect the allergic population.