Contrary to popular beliefs about foods being chock-full of additives and artificial flavourings, it is natural foods which trigger the majority of food allergies.

In fact, any food that contains proteins has the potential to cause allergic reactions in some people, and staple crops contain tens of thousands of proteins, only a few of which have allergenic properties. Proteins in peanuts, cows milk, eggs, wheat, soya beans, tree nuts, fish and shellfish cause 90 per cent of all food allergies in Europe.

"An allergy is an abnormal reaction of the body to one or more substances that in the majority of people cause no symptoms", says Willy De Greef of ALSS (Applied Life Science Strategies) in a recent overview of the issue.

Strict procedures

While an allergy is, to a large extent, an inherited trait, concerns have been raised that with the advent of genetic engineering - which introduces new proteins into crops - proteins with allergenic properties might be introduced unwittingly into the genetically modified (GM) plants. On the back of these concerns, strict procedures for conducting safety studies have been recommended by the WHO, the OECD and the US FDA, among others. As the study of allergies as a health problem has progressed in leaps and bounds over the past two decades, several methods of evaluating new products to determine if GM plants or other new foodstuffs contain a known source of allergens are now available.

Three rigorous sets of tests are applied; if a positive reaction occurs in any of these, work on the GM product is normally not pursued. However, if the crop is to be commercialised, then labelling of the foods derived from the GM plant would be necessary to warn consumers about the presence of the allergen.

However, points out De Greef, while these extensive safety assessment procedures have been implemented to minimise the possibility that allergenic proteins will be introduced into GM crops, "it is impossible to give an absolute guarantee that no one will become allergic to a food". Nevertheless, the tests are, without a doubt, the strictest method of reducing the chance that an unexpected allergy will occur in GM plants and novel foods.

Who needs allergens?

The other side of the coin, says De Greef, is that since genetic engineering can be used to "add beneficial proteins to a plant, it could also be used to remove allergenic proteins if they do not perform a vital function in the crop". "It is unlikely", he continues, "that allergens have a vital function, since most of them are storage proteins, meaning that they serve only as food reserves for the germinating seed. This means that this new application of genetic engineering is set to provide alternative, non-allergenic versions of certain foodstuffs for people who suffer from food allergies".

Currently underway is the compilation of databases of the major allergen proteins in crops as a first step in creating allergen-free varieties. Examples are GenBank, EMBL, PIR and SwissProt. The next step will be to identify, and then isolate, the gene coding for the particular allergenic protein and then to construct a system whereby production of that protein can be avoided.

The most advanced project of this kind is underway in Japan where, says De Greef, scientists are "well on their way to developing GM rice, minus the major allergen". This new rice would bring considerable relief to certain people in South East Asia who currently suffer from an allergy to this basic food in their daily diet.

For more information:

Willy De Greef, ALSS

FOOD TODAY 06/1998