WISHH : Why Choose Soy?

Soy Nutrition and Health: Soy Allergies

Food allergy, or food hypersensitivity, is actually a group of disorders characterized by an abnormal immunologic response to certain foods, resulting in a variety of symptoms. Soy protein has been rated 11th among foods in terms of allergenicity, although milk and eggs are also considered very allergenic foods. In healthy, non-allergic children, soy is generally less allergenic than cow's milk. The incidence of cow's milk allergy ranges from 0.3 to 7.5% among infants. Allergy to soy is seen in 0.5% or less of this population. Soy allergy is uncommon among adults.

Symptoms of soy allergy can range from more common harmless skin reactions and gastrointestinal disturbances to less common facial edema (swelling), dyspnea (shortness of breath), dysphagia (difficulty swallowing) and fainting—essentially an anaphylactic reaction. The median age at which infants present with allergy to either soy or cow's milk is 3 months. The symptoms (in descending order of frequency) are: diarrhea, vomiting, irritability, atopic dermatitis, rhinitis (inflammation of the nasal mucous membrane) and asthma. However, by 2 years of age the majority of infants outgrow the symptoms.

Anyone allergic to soy will probably have to avoid all soy products, which include hydrolyzed vegetable protein, textured soy protein (also called textured vegetable protein, TVP), isolated soy protein, miso, natto, okara, soy cheese, soy sauces (teriyaki, tamari, shoyu), soy protein concentrates, isolates and flours, soynuts, soygrits, soy oil, tempeh, yuba, soy beverages, and tofu products. Avoid lecithin if it is made from soy oil, instead of another type of plant oil. Soy meal and oil is utilized in a number of industrial products, including inks, soap, cosmetics, etc. One has to read labels extremely carefully and if in doubt about a particular ingredient, contact the manufacturer. Most products have an address and/or phone number on them.

Although it is not completely certain which specific component of soy is responsible for allergic reactions, at least 15 allergenic proteins have been found in soybeans using the sera of soybean-sensitive patients. One study found the protein 2S globulin had the highest allergenic capacity.

The way in which soyfoods are processed can affect allergenicity. In general, fermented soyfoods such as miso, tempeh, shoyu, tofu and natto are less allergenic than raw soybeans. Allergic reactions sometimes do not occur upon exposure to soy sauce because, in general, soy sauce is consumed in very low quantities and is low in protein (per gram) compared to other soy foods. Soybean oil that is completely free of protein should not produce allergic symptoms.

For persons allergic to soy wanting to consume isoflavones, these are also present in other legumes in smaller quantities.

Those allergic to soybeans may also cross-react to certain foods, such as peanuts, green peas, chickpeas, lima beans, string beans, wheat flour, rye flour, and barley flour.

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