Tracking potential allergens in novel ingredients, new science

Scientists at the Norwich-based Institute of Food Research (IFR) claim for the first time the distribution of plant food allergens has been measured according to protein families.

They suggest that just four 'superfamilies' account for more than 65 per cent of food allergens.

"Knowing what makes a protein more likely to become an allergen could make it easier for manufacturers to identify potential allergens in novel foods and ingredients, preventing them from reaching the consumer,"​ said Dr Clare Mills, head of the allergy research team at the IFR.

Scientists had already observed that although humans consume an enormous diversity of plant foods, just a few foods account for the majority of food allergies. However, their relatedness had remained unclear, an area that the IFR research may have illuminated.

Allergies are rising in humans with 8 per cent of children and 3 per cent of adults affected in Europe by food allergies or food intolerance, and new allergens emerging on a regular basis.

An estimated 2.5 million people in Europe and the US are now vulnerable to peanut allergies alone.

There is no current cure for food allergy and vigilance by an allergic individual is the only way to prevent a reaction but a peanut allergy can be so severe that only very tiny amounts can be enough to trigger a response.

Today, there are considerable legal requirements for the food industry working in the EU that aim to curb the risk for food allergy sufferers. The desire to avoid potentially harmful consumer confusion underpinned changes to the Labelling Directive 2000/13/EC that entered into force in November 2004. They essentially flag up to the consumer the presence of possible allergens in a food product.

The amendment heralds the mandatory inclusion on food labels of the most common food allergen ingredients and their derivatives: cereals containing gluten, fish, crustaceans, egg, peanut, soy, milk and dairy products including lactose, nuts, celery, mustard, sesame seed, and sulphites.

The UK researchers claim an enduring mystery for allergy researchers has been the unpredictable distribution of allergens in plants. For example, being allergic to birch pollen can predispose a person to allergy from distantly related plant foods such as celery, apple or soy.

Proteins are constructed from amino acids, and previous research has focused on analysing the sequence of amino acids to identify potential allergens. This can lead to false predictions, say the UK researchers, and sequence data alone does not reveal how amino acids interact to construct proteins.

The interaction of amino acids creates proteins folded into particular shapes and this latest IFR research investigated both amino acid sequence and structural similarities between surface features of plant proteins using a 3D computer model.

"By modelling surface features of proteins from a range of flowering plants, we were able to explain why cross-reactions can occur between species that otherwise seem dissimilar,"​ said Dr Mills.

She added that this is 'especially important to help us understand why people with an allergy to birch pollen can suffer related allergies to fresh fruits and vegetables'.

Flowering plants first appeared over 100 million years ago during the late Jurassic period, the age of the dinosaurs. Flowering plants became the most dominant plant on Earth and today include all our food plants. Very early in their evolution there was a split into two major groups. Some plant protein structures changed and some stayed the same or were 'conserved'.

"We found that even a single conserved region on the surface structure of a protein can cause cross-reactivity,"​ commented Dr Heimo Breiteneder of the Medical University of Vienna.

Full findings for the IFR research are published today in the Journal of Allergy and Clinical Immunology.​