Food allergy is common and a range of food products can cause food allergy.

Almost all food allergens are proteins. The production of genetically modified (GM) crops often involves the introduction of a new protein. Alternatively, the synthesis of a protein originally present in the crop may also be changed, thus altering the amount of such protein in the crop.

The World Health Organization (WHO) stated that GM foods currently available on the international market have passed risk assessments and are not likely to present risks for human health.

Safety assessment of GM food conducted by overseas authorities adopted similar scientific approaches as the one depicted in the guidelines for GM food safety assessment issued by the Codex Alimentarius Commission (Codex) in 2003. Allergenicity assessment is an essential component of the GM food safety assessment.

The initial step in safety assessment of GM food is to compare the GM food with its conventional counterpart. Any new or altered hazards are identified for further evaluations. Regarding allergenicity, all newly expressed proteins in GM food that could be present in the final food would be assessed for their potential to cause allergic reactions.

The allergenicity of GM foods currently available on the international market has been extensively evaluated. WHO stated that no allergic effect has been found in relation to GM foods currently on the international market.

An integrated, stepwise, and case-by-case approach is used in the allergenicity assessment of GM food.

The allergenicity assessment of GM food focuses on: 1) whether the original source of the GM food protein is allergenic; 2) whether the GM food protein is similar to known allergens; and 3) whether the GM food protein can remain intact after digestion.

Additional testing, including the use of specific immunological methods or animal models, is performed for further evaluation whenever necessary.

In 1996, research was conducted to improve the nutritional content of soya bean by expressing a Brazil-nut protein in it. However, the GM soya bean was found to be allergenic during the safety assessment. The whole project was terminated and the GM soya bean was never commercialised. This example illustrates the effectiveness of the GM food safety assessment in protecting public health.

Bt-protein Cry1Ac is a bacterial protein with insecticidal property and has been transferred to GM crops (including tomato and corn) for pest resistance. Addressing the concerns that Cry1Ac might be a potential allergen, Cry1Ac contained in approved GM crops has been extensively evaluated by national authorities as regards its allergenicity. It was shown to be not allergenic.

According to WHO, GM foods currently available on the international market have passed risk assessments and are not likely to present risks for human health. WHO also stated that no allergic effect has been found in relation to GM foods currently on the market.

GM foods that have been approved to date were fully assessed by national authorities for both safety and nutritional acceptability for all age groups, including infants.

The allergic risks posed by GM food are in principle no greater than conventional food. However, the public are advised to avoid food items that contain any ingredients which are known to be allergic to them.