History: The typical presentation is that of an infant who develops atopic dermatitis or cow milk protein intolerance, which resolves with substitution of a soy formula but recurs 1 or 2 weeks later. Parents may report a recrudescence of dermatitis or GI symptoms. Usually, the infant presents with watery diarrhea and vomiting.
Soy protein intolerance may cause different clinical syndromes, both IgE- and non–IgE-mediated. These reactions include the following:
Rhinitis
Urticaria or angioedema
Asthma
Anaphylaxis (rare)
Atopic dermatitis
Enterocolitis syndrome
Intestinal atrophy (malabsorption syndrome)
Eosinophilic gastroenteritis
Allergic proctocolitis
In susceptible individuals, the ingestion of soy proteins may cause the following:
Protracted diarrhea
Carbohydrate intolerance
Failure to thrive
Some children present with atopic dermatitis as a major symptom; however, most patients present with profuse vomiting and watery diarrhea.
The symptoms usually begin within 2 weeks of the infant's first feeding with soy-derived milk.
Sometimes mucus can be present in the stools, but blood is rarely noted.
Even if frank manifestations of colitis are absent, inflammatory changes in the colonic mucosa are frequently encountered.
The infant is usually dehydrated, and sometimes signs of malabsorption appear.
Small-bowel atrophy has been documented in different studies.
The degree of villous atrophy may be similar to that of celiac disease.
The mucosal damage causes malabsorption, hypoalbuminemia, and failure to thrive.
Some infants can present because of red blood mixed in stools. These infants usually appear healthy, and hematochezia is the only symptom.
Physical: The physical examination findings depend on the clinical picture and the duration of symptoms.
The most frequent presentation is enterocolitis syndrome; therefore, the infant appears dehydrated, with weight loss and sunken eyes.
In case of proctocolitis, the infant usually appears healthy and has normal weight gain.
In the less frequent case of soy-induced enteropathy, the infant has a low weight-to-length ratio and usually presents with dystrophia.
The signs and symptoms are related to the degree of the malnutrition. For example, edema is related to hypoalbuminemia; dermatitis enteropathica, to low zinc level; and rickets, to vitamin D deficiency.
Causes: All soybean proteins and foods currently available for human consumption contain significant amounts of the isoflavones daidzein and genistein, either as the unconjugate form or as different types of glycoside conjugates.
The isoflavones have structural homology to steroidal estrogens; therefore, they are considered to be phytoestrogens, but little is known about their biological activity.
Unquestionably, isoflavone ingestion can elicit biological effects; however, isoflavones and their metabolites have biological properties that are quite separate from classic estrogen action.
Genistein is a potent inhibitor of tyrosine kinases and can interfere with signal transduction pathways.
The threshold intake of dietary estrogens necessary to achieve a biological effect in healthy adults appears to be 30-50 mg/d.
In soy flours and concentrates, isoflavone concentrations are relatively high (0.5-3 mg/g). In soy milk and soy infant formulas, the concentration of isoflavones is lower (0.3-0.5 mg/g), but it is 10,000-fold higher than the concentration found in breast milk. Moreover, the volume intake of these products is sufficient to account for a significantly high dietary intake of isoflavones.
Infants fed soy-based formulas have plasma concentrations of isoflavones that are 3000- to 22,000-fold higher than plasma concentrations of estradiol.
Even if these substances have a weak estrogenic activity compared with estradiol, they could have adverse effects; however, the concerns about the adverse role of phytoestrogens in the first months of life are exclusively theoretical. At this time, the very limited available evidence from adult and infant populations indicates that dietary isoflavones in soy infant formulas do not adversely affect human growth, development, or reproduction.
The results of a study that enrolled 48 children (mean age, 37 mo; range, 7-96 mo) suggest that long-term feeding with SPFs in early life does not produce estrogenlike hormonal effects.
Gastroenteritis
Gastroesophageal Reflux
Ulcerative Colitis
Other Problems to be Considered:
Gastrointestinal bleeding
Celiac disease
Malabsorption syndrome
Infectious colitis
Enteropathy
Cow milk protein intolerance
Autoimmune enteropathy
Intractable diarrhea of infancy
Intestinal infections
Enterocolitis
Intestinal infections
Cow milk protein intolerance
Inflammatory Bowel Disease
Proctocolitis
Anal Fistulas and Fissures
Meckel Diverticulum
Intestinal duplication
Intestinal hemangiomas
Intestinal infections
Cow milk protein intolerance
Inflammatory Bowel Disease
Other Tests:
Soy-induced GI symptoms are usually not IgE-mediated; therefore, both skin tests and determination of specific IgE in serum have a low diagnostic value.
RAST appears to be of poor predictive value. Many children with positive results do not react to challenge tests.
Prick tests have little predictive value. The acidic subunits of glycinin and beta-conglycinin appear to be present in reduced amounts or absent in some commercial soybean skin test extracts tested by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. As a consequence, these commercial extracts are less sensitive than extracts of soy flour.
The challenge test with soy proteins, after an elimination diet, is the only reliable method of evaluating soy protein intolerance.
Procedures:
Endoscopy: During the workup for differential diagnoses, upper or lower GI endoscopies are often performed in patients with soy protein intolerance. Findings, however, are nonspecific, most commonly minimal, and, at times, even completely unremarkable. Accordingly, and because of the transient nature of the disorder, endoscopies are not considered essential.
Esophagogastroduodenoscopy
Macroscopically, only minimal erythematous changes may be observed.
Microscopically, any area (eg, lower esophagus, gastric body, antrum, duodenum) may or may not show signs of acute inflammation.
In a minority of patients, an infiltrate of eosinophils is observed.
When the clinical presentation is that of a malabsorption syndrome, the duodenal mucosa may have changes (eg, partial villous atrophy, crypt hyperplasia) indistinguishable from those of celiac disease.
Colonoscopy
Macroscopically, changes may vary from minimal erythematous segments, most commonly diffusely involving the distal colon, to severe inflammation with bleeding ulcers and loss of vascular markings.
Microscopically, nonspecific acute inflammatory changes are observed, typically indistinguishable from infectious colitis. Rarely, eosinophils predominate in the lamina propria.
I found this interesting. I am intolerant to soy. I posted a different article on soy allergy in the OMG I might be on to something page 402 or 403 I think. Not before page 400 for those interested in that.
