Health and Nutrition Corner: Quest for peanut allergy threshold – getting closer to answering “how much is too much”

By Dr. Andrew Craig, American Peanut Council Health Consultant

Nobody in the peanut industry likes “may contain” precautionary stickers which are too often plastered all over products just in case they may be contaminated by traces of peanut protein. Peanut allergic consumers dislike them too and the evidence is that overuse is confusing, anxiety-producing and, worse, encourages disregard and risk-taking. The UK’s FSA concluded in a recent study that the vast majority of “may contain peanut” products in the UK turned out to be perfectly safe because they didn’t contain any traces of peanut in the first place. That’s why the question of identifying thresholds for major allergens like peanut is high on the research agenda. If we knew with certainty that a specific amount, or less, of peanut allergen could be safely tolerated by the majority of allergic consumers, that would be a breakthrough benefitting everyone and make labelling more reliable and rational. The search for allergen thresholds has, therefore, become something of a quest for the food science holy grail.

In a 2014 review, the European Food Standards Authority concluded that we were still quite a distance from that objective. But they might have to revise that view in the light of findings reported by the University of Manchester this month in the Journal of Allergy and Clinical Immunology. A team led by Professor Clare Mills working under the umbrella of the EU’s EuroPrevall Project, which gathers threshold data from the European population, has identified the level of five of the most common European food allergens (peanut, hazelnut, celery, fish and shrimp) which would cause a reaction in the most sensitive ten percent of people.

The argument is that determining the threshold at which the most sensitive 10% of consumers would react to traces of peanut which were not supposed to be present and labelling products on that basis, would mean that the 90% of less sensitive consumers should not be at risk if there are allergen traces present below that threshold. As Prof Mills explained it, “What we wanted was to find a level of allergen which would only produce a reaction in the most sensitive ten percent of people. This sort of data can then be used to apply a consistent level of warning to food products. What we’d like to see are warnings which tell people with allergies to avoid certain products completely or just apply to those who are most sensitive.”

Work on possible peanut protein thresholds already exists and the Manchester team were able to achieve results using the EuroPrevall sample and double-blind, placebo controlled food challenges to demonstrate that their data and earlier work are of the same order. That is an assurance that the findings are valid. The Manchester results showed that objective peanut allergy symptoms appeared with ingested peanut protein amounts of between 2.8mg and 6.6mg. But since peanuts are only 25% protein by weight, the amount of whole peanut required to cause a reaction is larger: about 11.2 mg being the ingestible “dose” causing a reaction in the most sensitive individuals.

With the introduction EU-wide of the Food Information for Consumers (FIC) Regulations from mid-December 2014, the importance to industry and consumers of being able to use reliable information about the presence of possible food allergens could not be higher. As Prof Mills concluded, “This single study is part of the background to rolling out new warning guidelines across Europe, and alongside other work being carried out in Manchester and elsewhere we’re developing a strong evidence base to give consumers and industry confidence.”

The media reporting of this story sounds rosy, but actually this is not the end of the threshold quest as some big practical questions now need to be addressed both by the food industry and by peanut allergic consumers. One big question is will consumers accept thresholds if they are set at the 10% reacting level, or will food allergy advocates demand it be reduced to 1% or lower? Prof Mills addressed that point: “Threshold doses below which no patient with food allergy will react are a theoretic possibility, but appear to be less than the 3 micrograms protein level used in this study. Thus it is unlikely that threshold doses can be derived and then implemented in food factories in a manner that protects all patients with food allergy against any reaction.” So thresholds much lower than 10% are probably not feasible.

Other questions remain for which there are presently no answers, particularly about costs. Who will do the analysis of products to see if they comply with thresholds once they are set? What will the costs of this be and who will bear those costs? Finally, even if thresholds could be uniformly and reliably implemented across the EU’s multi-country single market, what about products possibly contaminated by peanut (or other allergens) coming in to the EU from outside that area? Identifying these outstanding issues shows that establishing allergen thresholds is not the end of the story. It kicks off a whole new round of questions, even as some of the questions about thresholds themselves are finding answers.


‘How much is too much?: threshold dose distributions for five food allergens’ Journal of Allergy, Asthma and Clinical Immunology in-press article
An infographic showing the threshold amounts of foods required to cause reactions identified in this study is found at