'May contain traces of nuts' – but what does that mean for allergies?
When someone suffering from a potentially fatal nut allergy reads "may contain traces of nuts" on a food product label, just how worried should they be? That's what scientists at the University of Manchester set about finding out.
The research could be life-saving because, while allergenic ingredients used in a recipe have to be listed on food labels, traces of allergens that find their way into foods by accident – say when a food-processing company makes both nut and non-nut products – are not currently regulated.
Labels currently warn of such traces with phrases, such as "may contain traces of nuts", or "produced in a factory which also handles peanuts", but there is no consistency or indication of how much of the allergenic product may have found its way into other products.
Further complicating matters, different people can tolerate more of an allergen than others.
To rate the risk, researchers, gave 436 people who suffered from allergies to peanut, hazelnut, celery, fish or shrimp small doses of the food they were allergic to and monitored their reactions.
"What we 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," says Professor Clare Mills, who led the study published in the Journal of Allergy and Clinical Immunology.
"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."
What they found was that between 1.6 and 10.1 milligrams (1/1000 of a gram) of hazelnut, peanut and celery protein produced a reaction in the most sensitive 10% of those studied.
For fish it was higher – at 27.3 milligrams – and for shrimp a significantly higher 2.5 grams of cooked protein produced a reaction – although the researchers didn't study raw shrimp which may have a different effect.
The University of Manchester is part of a project "Integrated Approaches to Food Allergen and Allergy Management" (iFAAM), which aims to provide better advice for health workers and the public and, ultimately reduce the burden of allergy across Europe.
Professor Mills added: "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."