Soya bean is a member of the bean family native to East Asia. Soya allergy is seen more commonly in infants and preschool children. About 4 in 1000 children are thought to have the allergy.
About half of children have symptoms that begin straight after eating food containing soya. Most of these symptoms are mild and may include a rash (hives or “nettle” rash), swelling of the lips or around the eyes, and itch. Some children have an itchy throat; others feel sick, vomit or have diarrhoea.
Severe reactions are much less common, but include difficulty breathing (with wheeze or swelling that blocks the mouth or throat), feeling faint or dizzy (Anaphylaxis).
In other children symptoms are delayed. Common complaints are flares in the child’s eczema, colic or belly ache.
Most people with soya allergy only have mild reactions. Severe reactions affecting the child’s breathing can occur, particularly in those with bad asthma and these need urgent medical attention.
One in ten children who are milk allergic are also allergic to soya. In most children this comes to attention when soya is used as an alternative following the child’s reaction to dairy products.
The diagnosis of soya allergy is based on the history of a typical reaction after contact with soya.
Positive allergy tests skin prick or blood IgE tests support the diagnosis, but should not be used alone, as people can have positive allergy tests but tolerate the soya without getting a reaction. Skin prick tests are safe and can be done in clinic provided that the child has not had any antihistamines for a few days. Blood tests are not affected by antihistamines, but the results are only available in a week or so after the clinic appointment. If the diagnosis is uncertain an oral soya challenge is sometimes recommended.
Soya is a popular vegetarian alternative to meat and many processed foods contain soya. It is also an ingredient in lots of cow’s milk and lactose free recipes. You should read the ingredients list on pre-packaged foods.
Soya can be avoided by looking for words like soy, miso, tempeh, tofu, bean curd and hydrolysed or textured vegetable protein.
Some Chinese recipes can contain soy sprouts and soya sauce and should be avoided. Soya can be found in many readymade meals like pot noodles, tinned spaghetti.
It is present in crisps like Quavers and Monster Munch and in most bread bought in the supermarkets.
A written management plan will be provided and appropriate medication prescribed which should be available at all times.
If soya is accidentally eaten spit the food out straight away and give an antihistamine as soon as possible.
- Difficulty breathing (wheezing, noisy breathing)
- Swelling in the throat (noisy breathing, drooling)
- Feeling faint or dizzy, looking very pale (lie the child down with their legs raised).
If any of these severe symptoms occur get help straight away and dial 999 stating “anaphylaxis” (ana-fil-ak-sis).
It is important to inform the nursery/school and any after school clubs. Any other carers such as grandparents, relatives and school friends’ parents will also need to know.
Half of those with soya allergy will outgrow it by 7 years of age. Nearly 70% of children outgrow by 10 years of age. If there has been no reaction for a long time and allergy tests to soya are negative an oral challenge may be suggested.
There is no cure for soya allergy at present.