Soy protein and products made from it, such as soya milk, can result in a dangerous allergy when ingested, especially in infants and young children who consume soya milk formula as a replacement for breastfeeding or cow’s milk. Soya milk formula for infants was introduced in the United States in the early 1900s and today is given to approximately 25 percent of infants at some time during the first year of life. Many infants outgrow soy allergies so an allergy to soya milk is less common in adults.
Prevalence
Soya milk allergies appear to affect 1 to 6 percent of infants, according to Environmental Health Perspectives. Soya milk allergies may be higher in people with ethnic or vegetarian dietary restrictions or in children with lactose intolerance or are allergic to cow’s milk. About 8 to 14 percent of children and 25 percent of infants with cow's milk intolerance are also sensitive to soy.
Allergens
An allergic response to soy causes the immune system to produce excessive amounts of antibodies against soy proteins called IgE. Some people are allergic to soya although they lack IgE allergy antibodies but display gastrointestinal symptoms, according to the Children's Hospital in Westmead. Some individuals with a positive allergy test to soy do not react when exposed to soya milk, a condition especially occurring in children with an allergy to peanuts. The Fujita Health University School of Medicine in Japan performed protein analysis on soy and classified the allergic reaction to soya milk as pollen-food syndrome, or PFAS, as published in the “Journal of Dermatology.”
Symptoms
An allergic reaction to soya milk may cause mild symptoms including hives, tingling in the mouth, dizziness or sneezing. More severe symptoms may include shortness of breath, difficulty swallowing, drop in blood pressure or fainting, according to the Cleveland Clinic. In rare cases soy allergies may cause anaphylactic shock and are life-threatening, according to the Mayo Clinic.
Safer Soya Milk for Infants
Infant soya formula is hydrolyzed to make it hypoallergenic for infants who have allergic conditions, such as asthma and eczema. Hydrolyzed formulas are made by breaking down the larger protein chains into short, easier-to-digest proteins. A 2003 study in Poland estimated the prevalence of soya allergy in 97 children aged 6 months to 4 years old. Conclusions suggested a high prevalence of soya protein allergy in children, especially those allergic to cow's milk. Results recommended hydrolyzed formula as the preferred choice for children with allergies.
References
- “Journal of Pediatric Gastroenterology and Nutrition”; Soy Protein Infant Formulae and Follow-On Formulae: A Commentary by the ESPGHAN Committee on Nutrition; University of Milano, Italy, et al.; April 2006
- Soyconnection.com: "Estimating Prevalence of Soy Protein Allergy"; Steve L. Taylor, Ph.D.
- Environmental Health Perspectives; "Food Allergy: An Overview"; Rhoda Sheryl Kagan; 2003
- Calgary Allergy Network; "Milk Allergy"; Anthony Pong, MBBS
- The Children’s Hospital at Westmead; "Fact Sheet; Soy Allergy"; 2009
- “Journal of Dermatology”; Two Cases of Pollen-Food Allergy Syndrome to Soy Milk Diagnosed by Skin Prick Test, Specific Serum Immunoglobulin E and Microarray Analysis; A. Yagami; 2009
- Cleveland Clinic; "Diseases & Conditions; Soy Allergy"
- MayoClinic; "Soy Allergy"
- “Medycyna Wieku Rozwojowago”; Prevalence of Soya Allergy in Children with Cow's Milk Allergy; A. Szaflarska-Szczepanik et al.; 2003
