Recent research identifies levels at which five foods may trigger allergic reactions

For people with food allergies, vague warnings on food products - such as "may contain nuts" - can be confusing; is the product safe to consume or not? 

In a new study, researchers claim to have identified the levels at which five common food allergens - peanut, hazelnut, celery, fish and shrimp - cause a reaction in only 10% of people who are allergic to them.

Around 90% of food allergies are caused by eight foods: milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat and soybeans. Peanuts are the most common trigger of food-allergic reactions in the US.

The research team at the Institute of Inflammation and Repair at the University of Manchester in the United Kingdom (UK) - says they hope the findings will lead to improved allergy warnings on food products.

Approximately 15 million people in the US have food allergies, with children accounting for around 6 million of these cases. Around 90% of food allergies are caused by eight foods: milk, eggs, fish, crustacean shellfish, tree nuts, peanuts, wheat and soybeans. Peanuts are the most common trigger of food-allergic reactions in the USA.

The Food Allergen Labeling and Consumer Protection Act of 2004 states that the eight primary food allergens must be clearly labeled in simple terms on food products, either through an allergen statement or in the ingredient list.

For food products that accidentally contain traces of allergens - due to being made in a factory that handles the allergens, for example - precautionary warnings may be applied to labels. But this precautionary labeling is neither consistent nor regulated.

The research team notes that food allergy sufferers have varying levels of tolerance to allergens, and inconsistent precautionary labeling may lead to confusion and risk taking among consumers.

What the researchers wanted was to find a level of allergen which would only produce a reaction in the most sensitive 10% of people. This sort of data can then be used to apply a consistent level of warning to food products.

1.6-10.1 mg of hazelnut, peanut or celery protein needed to trigger allergic reaction

For their study, published in the Journal of Allergy and Clinical Immunology, the researchers analyzed data from 436 people who were allergic to peanuts, hazelnuts, celery, fish or shrimp.

All subjects were drawn from the EuroPrevall project - a scheme that aims to assess the underlying risk factors associated with food allergies and their epidemiology across the European population.

Each participant was required to take part in a food challenge, which involved consuming small doses of the food they were allergic to while researchers monitored their reactions.

In the 10% of participants who were most sensitive to food allergens, the team found that between 1.6-10.1 mg of hazelnut, peanut and celery protein needed to be consumed to trigger an allergic reaction, while 27.3 mg of fish and 2.5 g of shrimp protein were required to produce a response.

The research team says they hope these findings will better inform food allergy sufferers of the allergen doses that may trigger a reaction, as well as contribute to improved food product labeling. 

"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."

In August 2014, another team of researchers from the Johns Hopkins Children's Center in Baltimore, MD, suggested that children who live in inner-city areas may be more likely to develop food allergies.

References:

1.  How much is too much?: Threshold dose distributions for 5 food allergens, Clare Mills, et al., Journal of Allergy and Clinical Immunology, doi: http://dx.doi.org/10.1016/j.jaci.2014.10.047, published online 12 January 2015, abstract.
2.  University of Manchester news release, accessed 12 January 2015.
3.  Additional source: Food Allergy Research & Education, Food allergy facts and statistics for the US, accessed 12 January 2014.