Understanding Soya Allergies


According to the Department of Agriculture, Forestry and Fisheries there is a growing interest in soybean products in South Africa because of the health benefits associated with these products. Soybean consumption in the country is estimated at 92% for animal feeds and 8% for human consumption. As soy foods become more popular there are concerns that allergic reactions to soy may become more common.

First let’s understand what a food allergy is. Food allergies occur when the body’s immune system abnormally reacts to proteins in a food soon after eating it. The immune systems of a person suffering from a food allergy identify the proteins (allergens) as harmful and produce antibodies to try to attack them. This then results into symptoms like wheezing, runny nose, sneezing, coughing, hoarseness, throat tightness, rash, vomiting, diarrhoea, swollen eyes, red spots, asthma and in severe cases anaphylaxis – a potentially life threatening reaction where more than one part of the body is affected.

Allergies do not affect a large percentage of people in most countries. Studies examining populations over the last 10 to 15 years suggest that approximately 2 to 4% of the population in most countries suffer from a true food allergy, with higher rates among children – 5 to 8%. Many food allergies start in childhood, but these allergies disappear as children get older and by the age of 5, approximately 80% of allergic children will lose their food allergy.

There are about 160 possible allergens, but there are 8 allergens accounting for 90% of food allergies. These allergens are milk, eggs, peanuts, tree nuts (almonds, cashews, walnuts), fish, shellfish, soy and wheat. Worldwide the most common food allergens in children are milk and eggs and in adults shellfish, peanuts, tree nuts and fish.

Soya is one of the 8 most common allergens, but how many people suffer from a true soy allergy? Soy allergy is much less common than other food allergies. A large US study, including nearly 5000 adults, found that the prevalence of self-reported allergies to soy was much lower than other foods. Supporting this result the College of Allergy, Asthma, and Immunology estimates that approximately 0.4 %of American children are allergic to soy, whereas the more frequent allergies reported was milk (32%), peanuts (29 %), eggs (18 %) and tree nuts (6 %).  Similar to other food allergies by the age of 10 approximately 70% of children will have outgrown their allergy to soy.

The concerned still is if the intake of soya food increase, the allergy prevalence would also increase. For this hypothesis we would expect that in countries where soy is typically eaten like Asia, soy allergy would be higher than in non-soy eating countries. However this is not the case. Research from Japan, China, Thailand and Hong Kong show soy allergy (the same as non-soy eating countries), is less common than allergy to milk and eggs.

Soy protein, like any protein, may cause an allergic reaction in sensitive individuals; however it is less common than other food allergies in both adults and children. It also occurs more frequently in children than in adults. Lastly, symptoms of soy allergy are similar to other food allergies, yet severe reactions are rare.

Article for @futurelifeZA by Suzelle Neuhoff

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