Natural history of soy allergy and/or intolerance in children, and clinical use of soy‐protein formulas

Abstract

Atopic diseases of infants and children are common, debilitating, chronic and sometimes even life-threatening. Several well-conducted studies in high risk babies have demonstrated a significant reduction in the prevalence and severity of atopic diseases with dietary and environmental manipulations. The currently available cow's milk (CM) substitutes for infants are soy protein (SP) formulas (SPFs), hydrolyzed formulas (HF), and home-made meat-based formulas. Soybeans have been cultivated in Eastern countries for many centuries and were first used to feed US babies with CM allergy (CMA) in 1929. Since then, SPFs containing purified SP, a mixture of vegetable oils, and purified carbohydrate have been developed. From a nutritional point of view, SPFs are adequate, support normal growth, protein status, bone mineralization, are well accepted, and economical. SPFs are used for different conditions including CMA, lactose and galactose intolerance and in the management of severe gastroenteritis, and some studies show that feeding SPFs for the first six months of life significantly reduces the prevalence of atopic diseases in high risk babies. Although gastrointestinal symptoms and atopic dermatitis (AD) may occur in some SPF-fed children, anaphylaxis following the ingestion of soybean is extremely rare in children. However, in the past few years the antigenicity/allergenicity of SPFs has been over-emphasized in the medical literature. In this paper on the natural history of soy antigenicity/allergenicity we discuss all the pros and cons of SPFs, their composition and nutritional value, the basic immune definitions, chemistry and characterization of SPs. We then discuss the antigenicity and allergenicity of SPFs in animals, recent data on the use of SPFs and the incidence of soy allergy in children, clinical reactions to SPFs, and the clinical relevance of skin testing and IgE antibodies to soy, challenge test procedure, clinical indication of SPFs, and their relevance in the prevention of atopy. We have meta-analyzed 17 different studies and conclude that history-based SPF allergy incidence totals 27%, in skin prick tests (SPT) RAST-oral food challenge (OFC)/double-blind food challenge (DBFC)-based epidemiological studies attains 3%, and in challenge test studies 4%. We suggest that double-blind placebo-controlled food challenge (DBPCFC) studies in larger cohorts of babies may establish a more reliable prevalence of SPF allergy in different disorders associated with CMA.

Over-Estimation of Soy Allergenicity: Laboratory Versus Challenge Tests: A Meta-Analysis

“…Some studies have shown that feeding SPFs for the first six months of life significantly reduces the prevalence of atopic diseases in high risk babies. Several studies have confirmed the preventive effect of breastfeeding supplemented with SPFs [1][2][3] but others did not confirm this assumption [4,5].…”

“…We have reviewed eight pertinent studies [1] and found a mean of 20% of reactions, also considering two studies limited to 9 or 10 children and one that found a 0% prevalence [1,28]. This also means that 80-100% of infants and children with gastrointestinal disorders can ingest SPFs with impunity.…”

“…Gastrointestinal symptoms may occur in some SPF-fed children, however anaphylaxis following the ingestion of SPFs is extremely rare and have provoked a clinical case of anaphylaxis every 22.3 years [1].…”

“…In contrast to hydrolysate formulas (HFs), SPFs do not cross-react with IgE antibodies to CM. Therefore SPFs could be used in babies with IgE-mediated CMA [1], but HFs should not be used in these infants, but only in children with food intolerance [26].…”

Atopic Dermatitis and Allergen Hypersensitivity: State of the Art

“…As regards the allergenicity of soy, we have studied 143 children with a median age of 12 months affected by AD, who had been soy-protein-formula fed for at least three months [51]. Only 4/36 children with positive RAST to soy had a positive challenge test to soy.…”