Antigenicity of infant formulas and the induction of systemic immunological tolerance by oral feeding: cow's milk versus soy milk

Use of Soy-Based Formulas and Cow's Milk Allergy: Lights and Shadows

Soybean (Glycine max) is a species of legume native to East Asia and used in childhood diet for over 2,000 years in the East. Soy protein formulas have been available for almost a century. Nowadays, the increase in cow's milk allergy and vegetarian dietary preferences are driving consumers toward cow's milk alternatives. In this paper, we reviewed the nutritional composition of soy-based infant formula and discussed their possible use in pediatric age, mainly focusing on prevention and treatment of cow's milk allergy. Protein quality is determined by digestibility and amino acid content. Purified or concentrated vegetable proteins (e.g., soy protein and gluten) have high digestibility (>95%), similar to those of animal ones. For some intact vegetable products (e.g., whole cereals and pulses), protein digestibility is lower (80-90%). Food processing and heat treatment also influence protein digestibility. Considering these data, we tried to evaluate the possible use of soybean and derivatives in pediatric age, including the nutritional composition of soy formulas and the clinical indications for their use. Moreover, since plant-based beverages are being perceived as healthy by consumers and their use is growing on the market, we recommend that soy drink should not be used as a substitute for infant formulas or cow's milk in children younger than 24 months.

Advances of research on glycinin and β-conglycinin: a review of two major soybean allergenic proteins

Being an important crop, soybean is widely used in the world and plays a vital role in human and animal nutrition. However, it contains several antinutritional factors (ANFs) including soybean agglutinin, soybean protease inhibitors, soybean allergenic proteins, etc., that may result in poor food utilization, decreased growth performance, and even disease. Among these ANFs, soybean allergenic proteins can lead to allergic reactions in human and animals, which has become a public problem all over the world, but our knowledge on it is still inadequate. This paper aims to provide an update on the characteristics, detection or exploration methods, and in vivo research models of soybean allergenic proteins; especially glycinin and β-conglycinin are deeply discussed. Through this review, we may have a better understanding on the advances of research on these two soybean allergenic proteins. Besides, the ingredient processing used to reduce the allergenicity of soybean is also reviewed.

Tolerance to a new free amino acid-based formula in children with IgE or non-IgE-mediated cow's milk allergy: a randomized controlled clinical trial

Background

Amino acid-based formulas (Aaf) are increasingly used in children with cow’s milk allergy (CMA). To be labeled hypoallergenic these formulas must demonstrate in clinical studies that they don’t provoke reactions in 90% of subjects with confirmed CMA with 95% confidence when given in prospective randomized, double-blind, placebo-controlled challenge (DBPCFC) trials. The majority of available safety data on Aaf derived from patients with IgE-mediated CMA. Considering substantial differences in the immunologic mechanism and clinical presentation of non-IgE-mediated CMA it’s important to investigate the hypoallergenicity of these formulas also in these patients. We prospectively assessed the tolerance to a new commercially available Aaf in children affected by IgE- or non-IgE-mediated CMA.

Methods

Consecutive patients affected by IgE- or non-IgE-mediated CMA, aged ≤ 4 years, were enrolled. DBPCFC was carried out with increasing doses of the new Aaf (Sineall, Humana, Milan, Italy), using validated Aaf as placebo. Faecal concentrations of calprotectin (FC) and eosinophilic cationic protein (ECP) were monitored.

Results

Sixty patients (44 male, 73.3%, median age 37, 95%CI 34.5–39.6 months, IgE-mediated CMA 29, 48.3%) were enrolled. At the diagnosis clinical symptoms were gastrointestinal (46.6%), cutaneous (36.6%), respiratory (23.3%), and systemic (10.0%). After DBPCFC with the new Aaf, no patient presented early or delayed clinical reactions. Faecal concentration of calprotectin and of ECP remained stable after the exposure to the new Aaf.

Conclusions

The new Aaf is well tolerated in children with IgE- or non-IgE-mediated CMA, and it could be used as a safe dietotherapy regimen for children with this condition.

Trial registration

The trial was registered in the ClinicalTrials.gov Protocol Registration System (ID number: NCT01622426).

Use of soy protein-based formulas in infant feeding

Soy protein-based formulas have been available for almost 100 years. Since the first use of soy formula as a milk substitute for an infant unable to tolerate a cow milk protein-based formula, the formulation has changed to the current soy protein isolate. Despite very limited indications for its use, soy protein-based formulas in the United States may account for nearly 25% of the formula market. This report reviews the limited indications and contraindications of soy formulas. It will also review the potential harmful effects of soy protein-based formulas and the phytoestrogens contained in these formulas.

A hydrolysed rice-based formula is tolerated by children with cow's milk allergy: a multi-centre study

BACKGROUND

Children allergic to cow's milk are fed a soy- or a hydrolysed cow's milk-based substitute. Neither can rule out a sensitization risk. Previous studies have shown that hydrolysed rice is tolerated by animals and children with multiple food hypersensitivities.

OBJECTIVE

A prospective clinical assessment of tolerance to a rice-based hydrolysed formula was carried out in children allergic to cow's milk. Patients and methods One hundred children (42 girls and 58 boys, mean age 3.17+/-2.93 years, median 2.20, range 0.18-14.6 years) with a history of immediate reactions to cow's milk and confirmed at double-blind, placebo-controlled food challenge (DBPCFC) when not contraindicated were assessed for clinical tolerance to cow's milk proteins. Their allergy work-up included skin prick tests with whole milk, alpha-lactalbumin (ALA), beta-lactoglobulin (BLG) and total caseins, and specific IgE determinations using CAP technology were performed against whole milk, ALA, BLG and casein. Sensitization to rice and rice-based hydrolysed formula was similarly investigated. Patients' sera were evaluated at immunoblotting for specific IgE to cow's milk proteins, rice and rice-based hydrolysed formula. DBPCFC was carried out with increasing doses of a rice-based hydrolysed formula.

RESULTS

All patients were sensitized to cow's milk and/or at least one cow's milk protein fraction. Eighty-seven out of 99 were positive to cow's milk and/or a cow's milk protein fraction at skin prick test. Positive (>0.35 kUA/L) specific IgE determinations were found for cow's milk and/or milk fractions (92/95), rice (21/91) and hydrolysed rice infant formula (4/91). At immunoblotting, sera from 96 children were positive to alpha-casein (n=54), beta-casein (n=38), ALA (n=57), BLG (n=37) and bovine serum albumin (n=61). Similarly, although patients' sera often contained specific IgE against rice proteins at CAP (21/91) and immunoblotting (70/96), only six very weakly positive responses were observed against rice-based hydrolysed formula. All DBPCFC with rice-based hydrolysed formula were negative.

CONCLUSIONS

Rice-based hydrolysed formula is a possible alternative not only for children with multiple allergies, but also for children with cow's milk allergy.

Soy formulas and nonbovine milk

BACKGROUND

Cow's milk allergy is frequently observed during the first year of life when nutritional requirements are critical. In those cases where breast-feeding is not available, a safe and adequate substitute to cow's milk should be offered.

OBJECTIVE

The primary aim of this review is to evaluate the clinical use of milk derived from vegetable proteins, such as soy, or from animals such as goat, mare, or donkey, or elemental diet in children with cow's milk allergy.

METHODS

MEDLINE searches were conducted with key words such as soy, goat's milk, donkey's milk, mare's milk, and elemental diet. Additional articles were identified from references in books or articles. Original research papers and review articles from peer-reviewed journals were chosen.

RESULTS

Soy formulas are nutritionally adequate and can be used in children with immunoglobulin E-mediated nongastrointestinal manifestations of cow's milk allergy. Goat's milk is as allergenic as cow's milk. Mare's milk and donkey's milk may be used in selected cases of cow's milk allergy after appropriate modification to make them suitable for human infants. Elemental diets are usually restricted to the most severe cases of cow's milk allergy (ie, sensitivity to extensively hydrolyzed protein formulas).

CONCLUSIONS

Vegetable formulas obtained from soy and milk derived from other mammals, such as mare or donkey, homemade preparations, and elemental diet may represent valid alternatives for children with cow's milk allergy. Extensive clinical trials are needed on the safety profile of any alternative mammal-derived milk. The choice of alternative milk should take into account the clinical profile of the child allergic to cow's milk, particularly as concerns age, severity of symptoms, degree of sensitivity to cow's milk proteins, and any multiple food allergies.

Soy allergy is not common in atopic children: a multicenter study

The aim of the present study was to evaluate the prevalence of soy allergy (positive skin test and positive challenge test) in a large cohort of atopic children, many of them soy fed early in life for several months. In order to investigate the prevalence of soy allergy, two groups of children were enrolled into the study. The first group comprised a cohort of 505 children with personal history suggestive of food allergy. The second group included 243 children born of atopic parents, who had been soy protein formula fed for the first six months of life for the prevention of cow's milk allergy and who had been prospectively followed up, from birth to 5 years. As regards the prevalence of soy allergy in the cohort of children suffering from allergic disease: 31/505 children (6%) had positive skin prick test to soy, however only six of the 31 children with positive skin prick test to soy had positive challenge test to soy. With regard to the prevalence of soy allergy in the children who had been soy protein formula fed in the first six months of life (second group): 14/243 children (6%) had positive skin prick test to soy, but the double blind placebo control oral food challenge to soy was positive in only one of these 14 children. In conclusion documented soy allergy is not common in atopic children.

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

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.

Implications of antinutritional components in soybean foods

There are a number of components present in soybeans that exert a negative impact on the nutritional quality of the protein. Among those factors that are destroyed by heat treatment are the protease inhibitors and lectins. Protease inhibitors exert their antinutritional effect by causing pancreatic hypertrophy/hyperplasia, which ultimately results in an inhibition of growth. The lectin, by virtue of its ability to bind to glycoprotein receptors on the epithelial cells lining the intestinal mucosa, inhibits growth by interfering with the absorption of nutrients. Of lesser significance are the antinutritional effects produced by relatively heat stable factors, such as goitrogens, tannins, phytoestrogens, flatus-producing oligosaccharides, phytate, and saponins. Other diverse but ill-defined factors appear to increase the requirements for vitamins A, B12, D, and E. The processing of soybeans under severe alkaline conditions leads to the formation of lysinoalanine, which has been shown to damage the kidneys of rats. This is not generally true, however, for edible soy protein that has been produced under milder alkaline conditions. Also meriting consideration is the allergenic response that may sometimes occur in humans, as well as calves and piglets, on dietary exposure to soybeans.

Allergic proctocolitis in infants: a prospective clinicopathologic biopsy study

Allergic proctocolitis is a major cause of rectal bleeding in infants, but its clinical features and laboratory results are often nonspecific. Our previous retrospective study demonstrated that large numbers of eosinophils in colonic mucosal biopsy specimens were highly associated with cases of allergic proctocolitis. Therefore, we prospectively examined 60 colonic mucosal biopsy specimens from the same sites (4, 8, and 12 cm from the anal verge) in 20 infants with clinically confirmed allergic proctocolitis to validate this morphologic feature, to characterize its distribution, and to correlate these data with the clinical information. The patients (age range, 4 to 304 days) were fed breast milk or a variety of formulas and all presented with rectal bleeding. Sigmoidoscopic examination was abnormal in 19 cases, typically characterized by focal areas of mucosal erythema. The major histologic finding was a strikingly focal increase in the number of eosinophils in all mucosal compartments, with a predilection to aggregate in close association with lymphoid nodules. Eosinophilic infiltration varied not only between biopsies at different sites, but also within individual biopsy specimens. Only 12 of 20 patients (60%) had all three of their biopsy specimens categorized as abnormal; in the remainder, only one (four patients) or two (four patients) of the three biopsy specimens were abnormal. The average number of eosinophils per high-power field of lamina propria for all cases was 15.6. No significant correlation was identified between the number of eosinophils in the mucosa and the patient's age, length of illness, endoscopic appearance, or type of inciting formula. In summary, eosinophils appear to be an excellent marker for infantile allergic proctocolitis. Given the focal distribution of the eosinophils, multiple mucosal biopsy specimens should be obtained and several levels of each examined to confirm the diagnosis.

Allergenicity and nutritional adequacy of soy protein formulas

Soy protein formulas are used for different conditions, including cow milk protein allergy, lactose and galactose intolerance, and severe gastroenteritis. Feeding soy protein formulas to normal term infants is associated with normal growth, normal protein nutritional status, and normal bone mineralization. Recent studies of infants fed soy protein formulas exclusively during the first months of life revealed no immunologic abnormality; however, the use of such formulas for management of cow milk protein allergy and for prevention of atopy is controversial. Although in the past decade many studies have stressed soy allergenicity, soy allergenicity has been confirmed by the challenge test in only a few studies. In this article we review the studies dealing with the allergenicity of soy protein formulas. We also present our own data on their use in the prevention and management of cow milk protein allergy.