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Useful facts on soya allergy (soya)

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Soya allergy

Useful information concerning soya allergy – NAAF’s fact sheet

What is food allergy?

Allergic reactions to foodstuffs occur because the body reacts to certain proteins in the food. Some individuals experience extremely serious reactions, even involving tiny amounts of the food they are intolerant of. Others experience mild discomfort that subsides without dramatic consequences. Food allergy is more common among children than in adults. Most people grow out of food allergies as young children. It is not unusual to react to more than one type of foodstuff. If food that is an important source of nutrients is eliminated, it is necessary to find good alternatives, so that the diet remains healthy and varied.

What is soya allergy?

Soya allergy means that one has an allergic reaction to one or several of the proteins in soya beans. Soya beans are a type of pulse. From these it is possible to extract protein, starch, oil and fibre that in turn can be used as ingredients in compound foodstuffs.

Soya allergy will normally give an indication on a prick test and blood test (IgE antibodies) for soya. However, it is not unusual to have an indication on these tests even if one tolerates soya. This is due to cross-sensitivity with other pulses, or with birch pollen. Some persons that are allergic to birch pollen experience that they tolerate soya in prepared food, but react to cold soya products, such as soya drinks and soya yoghurt.

Where do we find soya protein?

As soya protein has a high nutritional content and many functional properties and so it is used as an ingredient in a wide variety of foodstuffs. Soya protein can for example be found in hamburgers, fishcakes, pizza, bread and other baked goods. Many replacement products for individuals with milk allergy and those with coeliac disease are based on soya. This is because soya protein is a good alternative (due to its nutritional content and technical functions) to milk protein and gluten. Soya is also the main component of soya sauce, miso, tofu and tempeh.

What reactions occur in soya allergy?

The kinds of reactions occurring in individuals with soya allergy (having eaten soya) vary. Reactions include diarrhoea, stomach pain, eczema, urticaria, asthma and allergic shock. Persons with birch pollen allergies who react to non-heated soya products most frequently react with intestinal symptoms.

How is soya allergy treated?

The only means of treating soya allergy is to exclude all foodstuffs containing soya protein from the diet. Those that from experience react only to cold soya drinks/yoghurt do not as a rule need to take soya as an ingredient in mixed products into account, as most baked goods, meat products etc. containing soya are heated.

What can a person with soya allergy eat?

Soya protein is not found in pure products derived from milk, egg, meat, fish, shellfish, fruit, nuts, oil or vegetables. Some persons with soya allergy, however, suffer reactions to other legumes such as peas, beans, lentils and peanuts, and have to avoid these foods. Soya protein is rarely found in confectionery and snacks. Vegetarian food, foreign dishes and health food products more commonly contain soya protein than typical Norwegian foodstuffs. Since soya protein is used in increasingly more foodstuffs, it is important to read the food ingredients carefully. According to the labelling regulations, all products containing soya must be clearly labelled.

What about soya oil?

Soya oil is considered to be safe for individuals with soya allergy. The manufacturing processes remove the proteins, which are the components in the oil that cause the allergic reactions. In other countries, analyses have been performed on oils with the conclusion that soya protein is found in some of them. Some of the largest manufacturers in Norway routinely take samples in order to check that there is no residue of soya protein in oil/margarine.

What about soya lecithin?

Soya lecithin is also a fat substance derived from soya beans. Soya lecithin can in some cases contain minute quantities of soya protein; however, this involves very minute quantities, and so the total amount of soya protein is minimal. Therefore it is not usual to advise those with soya allergies against consuming foodstuffs containing soya lecithin.