Create hypoallergenic products.

Allergens in foods are usually small proteins recognized by the immunoglobulin E immune system. They cause strong biological reactions in some humans. Among the strongest and most common natural allergens are celery, hazelnut, carrots and Prunoideae fruits, such as peaches, plums and apricots.

One of the most common causes of food allergies in infants and young children is the egg, although, according to studies, most youngsters outgrow the allergy by the age of five. The egg is made up of various proteins, many of which are highly allergenic. The four major allergenic proteins are ovomucoid, ovalbumin, ovotransfferin and lysozyme.

Most people with an egg allergy are allergic to the egg white proteins, but there also are those who are allergic to the yolk. The egg yolk contains different allergenic proteins than the egg white--apovitellenins I, apovitellenins VI and phosvitin. Those who suffer from an egg yolk allergy usually have the reaction triggered by inhaled bird antigens.

Vegetables also can potentially cause allergies. Using heat treatments or a chemical peeling process, many vegetable products may be made less allergenic to humans. Industry is increasingly adapting new techniques to reduce the potential for allergic reactions.

A group of European researchers has been working to develop hypoallergenic food products. The research team found several previously unknown allergens and determined their chemical structures, which were often quite similar across vegetable products. They then used genetic methods to produce a number of recombinant allergens. They will use these to develop improved diagnostic techniques for determining products that could cause allergies.

The scientists also heat-treated hazelnut and celery. They used the chemical peeling technique in peach and apricot. Heat-treated foods did not show a complete reduction in allergenicity. Some minor compounds were heat-resistant, triggering allergies in some subjects. However, chemically treated peaches and apricots provoked no adverse reactions in allergic subjects.

Food allergy has been in the headlines for several years partly because of a concern over introducing new allergens by genetically engineering crops. With knowledge of the protein structure of the allergens, researchers may be able to eliminate the genes that express the allergenic proteins from genetically modified vegetables.

Further information. Claudio Ortolani, Divisione Medica Bizzozero, Centro di Riferimento Regionale di Allergologia e Immunologia Clinica, Piazza Ospedale Maggiore 3, IT-20162 Milan, Italy; phone: [phone]; fax: [phone]; email: [e-mail].