Prevalence of Soy Allergies

Allergies to soy and soy products are most prevalent in infants and children rather than adults.  It is the second most prevalent allergen worldwide after peanut.  It is a transient allergy in childhood, like milk and egg, with researchers being unsure how common it is that children will or when they will grow out of them (1). As with peanut there is a geographical variation of soy allergy and is more prevalent where the food is a staple.  In Spain legume allergy is the fifth most prevalent food allergy within children and is more common than allergy to peanut (1).  In India, the major cause of allergy is lentils and chickpeas.   In France, lupin allergy is becoming more common, with the lupin seed flour being used in wheat flour (1).

Foods and Allergens

Legumes are dicotyledonous plants, belonging to the order of Fabales (1).  Many of the allergens in legumes are found in the vicilin superfamily, with the allergen structure dictating the cross reactivity between legumes.  Clinical cross-reactivity appears to be extremely rare (1).  Recent research has identified a 44% cross-reactivity between peanut and lupin flour.  Research has also shown 70% of children with lentil allergy also are allergic to chickpea (1). 

Food processing can also influence the allergenicity, with the high refinement of oils believed to remove all proteins within soybeans (1).  The fermentation of soy products does not alter the allergenicity of the soybean product (1).

Diagnosis of Soy Allergy

Skin prick testing appears to provide only a 50% predictive value when diagnosing soy allergy, hence diagnosis in adults and children relies on a good clinical history and medically supervised oral food challenge when clinical history is inconclusive (1).

Management

At present the only effective and proven management of any legume allergy is the total avoidance of the offending allergen (1).

Table: Foods likely to contain legumes

Legume

Foods Involved

 

Soy

Textured vegetable protein (TVP), vegetable burgers, tofu (soya-bean curd) tempeh, tamari, miso, soy sauce, pre-packaged Chinese meals, soya milks, soya yoghurts, soya desserts

 

Lupin

Lupin flour is often used in mainland Europe in pastries, breads and pizza bases, and lupin seeds are sometimes used in seeded breads

 

Chickpeas

Indian dishes, especially vegetarian, e.g. chana dhal; added as flour to some French breads, hummus

 

Lentils

Gram flour, chapattis, puri, dhal, vegetarian dishes

 

Tragacanth

Used as a thickening agent and stabilizer in food products, e.g. salad 
dressings, ice cream; used medicinally for digestive disorders (laxative effect) and coughs, so may be found within cough syrups and lozenges

 

Guar(E412)

Used as a thickener and emulsifier in foods, e.g. yoghurts, fruit juice drinks, ice creams, salad dressings

 

Fenugreek

Curry Powder

 

 

 

 

References: 
1.     Tanya Wright and Rosan Meyer., Dietary Management of Milk and Eggs -Food Hypersensitivity: diagnosing and managing food allergies and intolerances.  Edited by Isabel Skypala, Carina Venter; Wiley and Blackwell 2009, Part 2, p 117- 128. 
2.    Consumer Information: Information for Allergy Suffers: Food Standards Australia New Zealand, April 2010. www.foodstandards.gov.au

Submitted by: Julie Albrecht Consultant Dietician -Nutritionist A.P.D.

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