Soya allergy is a common childhood allergy. Most children grow out of it by the age of two, but occasionally adults are allergic to soya.
The symptoms of soya allergy are similar to milk allergy and they include rashes, diarrhoea, vomiting, stomach cramps and breathing difficulties. Some people with soya allergy might also react to milk. Very rarely, soya can cause anaphylaxis.
Soya is used as an ingredient in lots of food products, including some bakery goods, sweets, drinks, breakfast cereals, ice cream, margarine, pasta and processed meats.
Soya flour is used to increase the shelf life of many products and to improve the colour of pastry crusts. Textured soya protein is made from compressed soya flour. It's used as a meat substitute and to improve the consistency of meat products.
Since November 2005, food labelling rules require pre-packed food sold in the UK or the rest of the European Union (EU) to show clearly on the label if it contains soya (or if one of its ingredients contains it). Bear in mind that there could still be foods on the shelves that were produced before this date.
Refined soya oil (the main component of vegetable oil) should be safe for people with soya allergy, because the proteins that cause allergic reactions are removed during the refining process. For this reason, the new food labelling rules don't require soya oil to be labelled individually when used in blended vegetable oil.
Only give soya infant formula to your baby if your GP or health visitor has advised you to. In almost all cases, breastfeeding or another type of formula will be a better choice. Soya infant formula was originally developed for babies who can't have infant formula based on cows' milk, for example because of a milk allergy. But there are now other types of formula that are more suitable for these babies – ask your GP or health visitor for advice.
Occasionally, GPs or health visitors might recommend soya infant formula, for example if a baby can't or won't drink other types of formula, or if parents want a baby to eat a vegan diet and are not breastfeeding.
Sometimes people with an allergy to soya will also react to foods such as peanuts, peas, lentils, chickpeas, rye and barley flour.