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Allergic Reactions to Soybeans

Sep 13, 2011 | By Judy Wolfe
Allergic Reactions to Soybeans
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Soybeans, and soy-based foods, are in the top eight food allergens responsible for nearly 90 percent of all food allergies, according to the Food Allergy and Anaphylaxis Network. Up to 0.4 percent of children experience allergic reactions to soy. A Johns Hopkins Children's Center study published in the "Journal of Allergy and Clinical Immunology" found that as many as 31 percent of those children remain allergic after age 10. For some people, this allergy can be a lifelong condition.

Soy Allergens

Soybeans and soy products provide plant sources of complete proteins. Low in saturated fats, soybeans provide an inexpensive alternative to meat and dairy protein. They also, however, cause allergic reactions. An Abbott's Laboratory study published in the May 2004 issue of the "Journal of Nutrition" found that 16 soy proteins, all potentially allergenic, had been identified.

Allergy Mechanism

The digestive tract of nonallergenic person neutralizes soy proteins before they enter the bloodstream. In allergic individuals, however, the neutralizing mechanisms haven't fully matured. Proteins from the soybeans reach their bloodstream, attaching to IgE antibodies on immune system mast cells. The antibodies release protein-attacking chemicals, including histamines. These chemicals cause the symptoms associated with soy allergies. Many children outgrow these reactions as their gastrointestinal systems develop.

Symptoms

Allergy symptoms surface within a few minutes to a few hours after ingesting soybeans or soy-based foods. They range from minor to life-threatening. Digestive symptoms include cramps, nausea, vomiting and diarrhea. Other signs are itchy skin, a tingling mouth and swollen face, lips or tongue.

Anaphylaxis

Anaphylaxis, an extremely serious reaction, requires immediate medical attention. Signs of anaphylaxis include inflamed, itchy skin rash; swelling of the eyes and extremities; severe respiratory distress; a metallic taste; and plunging blood pressure or fainting. A three-year study at Uppsala, Sweden's University Hospital Department of Pediatrics, reexamined the frequency of soy-related anaphylaxis. The findings, published in the March 1999 issue of "Allergy," concluded that anaphylactic reactions to soy were more common than previously thought. The researchers also suggested the reactions were likelier in children with existing peanut allergies and asthma.

Soybean Intolerance

Soybean intolerance shares symptoms with soybean allergy. Intolerance symptoms, however, are typically milder. Unrelated to the immune system, they remain confined to digestive distress. Food intolerance develops over time; some food-intolerant people continue consuming small quantities of their troublesome foods without a reaction. Soy intolerance may result from insufficient soy-digesting enzymes, illness or sensitivity to other ingredients in soybean-based foods. Determining whether allergy or intolerance has triggered a soy reaction requires medical testing.

Living With Soybean Allergy

Food manufacturers must indicate the presence of soy on their product labels. But the pervasiveness of soy in other products makes avoidance a challenge. Cosmetics, vitamins, medications, plastics, ink, adhesives and solvents are other nonfood, soy-enhanced items. People with soybean allergy can react to touching or inhaling soy products as well as to consuming them. Anyone uncertain about a product's soy content should contact the manufacturer.

References

Article reviewed by Jay Lawrence Last updated on: Sep 13, 2011

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