July 2009 Issue

Pediatric Food Allergies
By Liesje Nieman Carney, RD, CNSD, LDN
Today’s Dietitian
Vol. 11 No. 7 P. 48

Suggested CDR Learning Codes: 2060, 3060, 4130, 4140, 4150, 5060, 5070, 5110; Level 2

According to The Food Allergy & Anaphylaxis Network, nearly 12 million Americans are affected by food allergies, including about 6% to 8% of children. Twenty-five percent of infants born to families with a history of atopic disease will develop food allergy by the age of 7.1

Allergy or Intolerance?
Sometimes the term “food allergy” is used interchangeably with “food intolerance,” but there is a distinct difference. Food intolerance is an adverse food-induced reaction that does not involve the immune system (eg, lactose intolerance) and does not produce life-threatening symptoms. Many people report intolerance to dyes, preservatives, MSG, and other additives. Avoidance is the only treatment.

Food allergies involve an immune response. The immune system fails to recognize food proteins as harmless, perceives them to be invading antigens, and responds by creating an antigen-specific antibody called immunoglobulin E (IgE). On second exposure to the antigen, IgE binds to the antigen, activating a cascade of events, including the release of histamine and other substances that cause an “allergic reaction.”2 This type of allergy is classified as an IgE-mediated allergy.

To complicate matters further, there is a second way in which the immune system may respond. During non–IgE-mediated allergic reactions, there is a release of T cells, which are a catalyst for the release of eosinophils, a type of white blood cell. Eosinophils generally protect the body by attacking and killing bacteria and other microorganisms (eg, parasites). The gastrointestinal tract (GI) normally has the most eosinophils in our body. Food protein-induced enterocolitis syndrome and food protein-induced proctocolitis syndrome are classic examples of non–IgE-mediated allergic reactions.

Disorders that involve both IgE- and T cell-mediated responses include eosinophilic esophagitis (EE), eosinophilic gastroenteritis (EG), and atopic dermatitis. These cases are the most difficult to treat and require close collaboration among an allergist, a gastroenterologist, and a dietitian.

In the case of EE and EG, eosinophils accumulate in the esophagus or stomach in response to the perceived antigen. The accumulation of too many eosinophils causes symptoms, which may include reflux, dysphagia, vomiting, and diarrhea.3 EE and EG have been observed in all age groups. Typically, many patients diagnosed with EE were previously treated for gastroesophageal reflux, but they did not respond to antireflux medication. The most common symptom of EE in children under the age of 5 is vomiting. In older children, reports of food impaction and nausea are more likely.2

Symptoms
Food allergy symptoms may be mild or severe. Respiratory symptoms may include acute rhinoconjunctivitis, bronchospasm, asthma, and anaphylaxis. Dermatological symptoms may include urticaria (hives), angioedema, and atopic dermatitis. GI symptoms can include pollen food allergy syndrome, GI anaphylaxis, food protein-induced enterocolitis or proctocolitis syndrome, and EE/EG. The cardiovascular system may exhibit hypotension or cardiac dysrhythmias. Although some symptoms are distinctive to one type of allergy, many overlap between the two types. Thus, proper testing and interpretation of the results must be emphasized.

Depending on the individual, the food protein antigen, and the type of allergy, reactions may occur immediately after ingestion or hours or days later. Some people are so severely allergic that they react to topical (touching a shrimp) or airborne exposure (sitting near someone opening a bag of peanuts).

Diagnosis
Testing methodology differs by allergy type, except for a thorough diet and medical history.

• IgE-mediated allergies: No test can guarantee that a positive result equates to a significant allergy. Performing thorough diet and medical histories, ordering appropriate tests, and interpreting test results accurately are all essential components of diagnosing IgE-mediated allergies. To ensure that these steps are taken, a child should be treated by an experienced and board-certified pediatric allergist. Several tests, such as skin prick tests and CAP RASTs (radioallergosorbent tests), may be needed to determine which foods to eliminate. However, be mindful that a positive skin prick/RAST only correlates with a positive challenge in 40% to 50% of cases.4

• Non–IgE-mediated allergies: Diagnosis may require several tests to decide which foods to eliminate. These may include endoscopy and a biopsy of the esophagus, stomach, and duodenum, as well as skin prick and/or atopy patch testing.

The following is a summary of tests, though no test can predict the severity of a food allergic reaction. Symptoms are the real determinants of whether the food allergy is considered mild, moderate, or severe.

• Skin prick test: A diluted extract of the suspected food is placed on the skin, and then the skin is scratched with a needle. After 15 minutes, each skin prick is reviewed, and the result is positive if a raised area/hive is present and is 3 mm or larger than the control (ie, saline). A negative test definitively confirms the absence of an IgE-mediated food allergy.

• Serum tests: These include RAST and quantitative measurements of food-specific IgE antibodies (CAP RAST or CAP System FEIA). Diagnostic levels of food-specific IgE for various foods have been reported.6 A large panel of foods should not be tested, as results can be difficult to interpret. Food should be chosen based on diet and medical history.

• Atopy patch testing: This is useful for identifying potential non–IgE-mediated food allergies. Fresh foods are prepared (semiliquid pudding consistency), put into aluminum chambers, and placed on a person’s back for 48 hours. Twenty-four hours after removal, interpretation is based on redness and swelling.2 A caution, though, as inconsistent methodology (different reagents used) can cause conflicting results for the same tests conducted at different facilities.

Several tests for diagnosing food allergies are questionable at best: specific immunoglobulin G antibodies, hair analysis, cytotoxic testing, electrodermal tests, applied kinesiology, iridology, provocation neutralization, and the pulse test. A full discussion of these tests is beyond the scope of this article, but more information is available in the literature.5

Prevention
Some pregnant women wonder whether avoiding known allergens, especially peanuts, will diminish the chances that their babies will develop food allergies. Unfortunately, the answer is no. Maternal dietary restrictions during pregnancy or lactation do not play a significant role in preventing atopic disease in infants.1 However, exclusively breast-feeding a high-risk infant for at least four months, instead of feeding intact cow’s milk protein-based formula, decreases the incidence of atopic dermatitis and milk allergy during the first two years of life.1 Use of soy-based formula does not prevent the development of allergies.

In 2000, the American Academy of Pediatrics made the following dietary recommendations for infants with a strong atopic family history:

• exclusive breast-feeding for six months;

• the use of hypoallergenic formulas (extensively hydrolyzed or elemental formula) when not breast-feeding;

• maternal dietary avoidance of peanuts and tree nuts during lactation and consideration of avoiding eggs, cow’s milk, and fish;

• delayed introduction of cow’s milk until 12 months of age, eggs until 24 months of age, and peanuts, tree nuts, and fish until the age of 3; and

• no maternal dietary restriction during pregnancy, with the possible exception of peanuts.

Treatment
No medication can cure food allergies; avoiding allergenic food(s) is the only way to prevent a reaction. But complying with a restricted diet is challenging. Since January 2006, the Food Allergy Labeling and Consumer Protection Act has made it easier for caregivers to determine whether an allergen is present by requiring manufacturers to identify on all product packaging ingredients derived from eight commonly allergenic foods: milk, egg, soybean, wheat, peanut, tree nut, fish, and crustacean shellfish. The information may be provided by listing the food in the ingredient list, identifying the allergen after the ingredient (eg, “farina (wheat)”), or making a “contains” statement (eg, “This product contains milk, soy, and wheat”).

Milk and wheat proteins are difficult to avoid because so many foods contain them. Foods in these categories also tend to be nutrient dense, so when people avoid these foods, they should choose substitutions that provide equivalent nutrients.

For instance, milk is an important source of calcium, vitamin D, and vitamin B12. Enriched soy milk is an appropriate substitution; however, some children have allergies to both milk and soy. In these cases, the most appropriate treatment is provision of a complete milk-free and soy-free formula (eg, protein hydrolysate or amino acid-based formula) to ensure adequate calorie, protein, vitamin, and mineral intake. Fortified rice milk provides calcium and vitamin D but does not contain sufficient protein or fat for young children. Goat, mare, buffalo, and ewe milks cross-react with cow’s milk protein and are not appropriate for children with cow’s milk protein allergy.

When people avoid wheat-containing products, they must find alternative vitamin and mineral sources, such as fortified cereals. Numerous companies manufacture “allergy-friendly” products. These items tend to be more expensive, but the benefits of their use include increased compliance with dietary restriction and improved quality of life for the child.

Nutritional Problems
A diet restricted on the presumption of a food allergy increases the risk of nutrient deficiencies, particularly in the period beyond infancy. Accurate diagnosis is crucial to ensure that a child is not placed on a restrictive diet without proper cause. A child with just one food allergy carries the lowest risk of developing nutrient deficiencies; with each additional allergy, there is an increasing risk of deficiencies and suboptimal growth. Nutrients provided by common food allergens include the following:

• Milk: Vitamin A, vitamin D, riboflavin, pantothenic acid, vitamin B12, calcium, and phosphorus;

• Egg: Vitamin B12, riboflavin, pantothenic acid, biotin, and selenium;

• Soy: Thiamin, riboflavin, pyridoxine, folate, calcium, phosphorus, magnesium, iron, and zinc;

• Wheat: Thiamin, riboflavin, niacin, iron, and folate (if fortified); and

• Peanut: Vitamin E, niacin, magnesium, manganese, and chromium.

A strict elimination diet is generally comprised of lamb or chicken, white rice, some vegetables, a few fruits, and a pediatric hypoallergenic formula. An unsupervised elimination diet often leads to poor nutritional status.

If a child with cow’s milk protein allergy has been exclusively breast-fed for the first six months of life, a dietitian should guide the caregivers to ensure nutritional adequacy during the transition to solids. This can be a difficult time, as there is significant concern about exposing the infant to a food protein allergen. Exclusive breast-feeding beyond six months does not provide adequate nutrients, particularly vitamin D, iron, zinc, and calcium. There are reports in the literature of infants with cow’s milk protein allergy who developed vitamin D-deficiency rickets and calcium-deficiency rickets due to inadequate supplementation.4

Infants with this allergy are at an increased risk of poor growth. Infants with poor compliance to the prescribed dietary interventions (eg, exclusive breast-feeding, soy formula, or hydrolyzed formula) tend to weigh less than those with good acceptance of the diet.7

In cases that warrant a strict elimination diet, it is often necessary to supplement with hypoallergenic formula and/or a multivitamin with minerals. Finding a hypoallergenic multivitamin supplement can be tricky if caregivers are not sure where to look, but there are a few companies that make hypoallergenic dietary supplements (eg, Freeda, Kirkman Labs) that can be found in large grocery stores. Pediatric hypoallergenic formulas that are amino acid based include EleCare (Abbott), and Neocate One+, Neocate Junior, unflavored, and E028 Splash (a flavored drink box), all from Nutricia North America.

Breast-Feeding Infants With Cow’s Milk Protein Allergy
The goal of maternal dietary restriction during lactation is to reduce an infant’s antigen exposure during breast-feeding. If a mother is breast-feeding and the infant is diagnosed with cow’s milk protein allergy, the mother may try a dairy-restricted diet. It is important that she makes an appropriate substitution in her diet to ensure adequate calcium intake. In some cases, the infant’s symptoms will improve or resolve and, in other instances, it is necessary to transition to a protein hydrolysate or elemental formula.

Approximately 50% to 60% of infants with cow’s milk protein allergy also have an allergy to soy. According to the American Academy of Pediatrics, soy formula should not be administered to infants with documented cow’s milk protein allergy enteropathy/enterocolitis because soy formulas are not tolerated by approximately 60% of infants with non–IgE-mediated cow’s milk protein allergy.8 After 6 months of age, it is acceptable to offer an infant soy formula in cases of documented IgE-mediated cow’s milk protein allergy; however, the infant may have a concurrent soy allergy.

There are a few additional concerns regarding the use of soy-based formulas. A recent study revealed a potential link between soy formula and peanut allergy, and the phytoestrogen content of soy may have the potential to induce Leydig cell failure in male animals.4

Extensively hydrolyzed hypoallergenic formulas are designed to be tolerated by 90% of infants with cow’s milk protein allergy.4 Protein in these formulas is comprised of free amino acids and peptides. Interestingly, however, all of the formulas in this category are derived from casein (a protein derived from cow’s milk). Currently, there are no proprietary products that contain extensively hydrolyzed whey protein, which is quite different from partially hydrolyzed whey protein.

Hydrolyzed infant formulas are the recommended first line of defense in cow’s milk protein allergy. If introduction is delayed until later in infancy, likelihood of acceptance is decreased. If infantile cow’s milk protein allergy is suspected, it is best to implement treatment as early as possible. 

Amino acid-based infant formulas are truly hypoallergenic and are the formulas of choice for infants who fail a trial of protein hydrolysate-based formulas. They have varying medium-chain triglyceride content because some infants prescribed these formulas have fat malabsorption in addition to protein sensitivity. These formulas have the highest osmolarity compared with all other infant formula categories. Most states require a prescription for these formulas.

In general, amino acid-based and protein hydrolysate formulas are equally efficacious in relieving cow’s milk protein allergy symptoms. Intolerance to hydrolysate formula may occur with non-IgE-mediated food-induced gastroenterocolitis-proctitis syndromes with failure to thrive, severe atopic eczema, or symptoms during exclusive breast-feeding.9

Introducing Complementary Foods
Zutavern et al concluded that there is no evidence to recommend delaying the introduction of solids beyond 4 to 6 months.10 Delayed introduction does not prevent asthma, allergic rhinitis, or food sensitization. However, very early introduction of solids can increase the risk of food allergy. In general, complementary feeding should not be introduced before 17 weeks but no later than 26 weeks; introducing gluten before 4 months or after 7 months should be avoided to reduce the risk of developing celiac disease and wheat allergy.11 Dairy products should be introduced no earlier than 12 months, and peanut, tree nuts, fish, and seafood at 36 months.12 Breast-feeding concurrently with the introduction of complementary foods may facilitate tolerance.

When a patient with cow’s milk protein allergy has his or her first birthday, options include switching to regular cow’s milk, a trial of enriched soy milk, or continuing on a hypoallergenic formula (protein hydrolysate or amino acid-based formula). If an infant has cow’s milk protein allergy but tolerates soy formula, it is preferable that he or she remain on soy formula beyond 1 year of age rather than switching to soy milk. An infant soy formula can be increased in caloric density to 30 kcal/oz (similar to standard pediatric enteral formulas) and is more nutritionally complete than soy milk. Another product available for this population is Bright Beginnings Soy Pediatric Drink (PBM Products), which is intended for children aged 1 to 10.

For an infant with cow’s milk protein allergy and soy allergy who was on a hypoallergenic formula (protein hydrolysate or amino acid-based formula), caregivers may independently choose to stop the formula at 1 year and switch to rice milk. However, enriched rice milk does not provide adequate calories, protein, or fat for a toddler, so children should be transitioned to a pediatric hypoallergenic formula. Flavoring the formula (eg, vanilla extract, strawberry syrup) or trialing a different hypoallergenic formula (eg, E028 Splash in various flavors) can increase acceptance.

Many children outgrow food allergies; however, peanut, tree nuts, fish, and shellfish have a strong likelihood of being lifelong allergies. Historically, children would outgrow cow’s milk protein allergy at approximately 2 to 3 years, but the age of 6 is now the average.

— Liesje Nieman Carney, RD, CNSD, LDN, is an active member of the American Dietetic Association’s Pediatric Nutrition Dietetic Practice Group, as well as the American Society for Parenteral and Enteral Nutrition. She is a clinical dietitian/publication specialist at the Children’s Hospital of Philadelphia. Her clinical areas of interest include neonatal and pediatric intensive care, nutrition support, and inborn errors of metabolism.

Sidebar
Companies Specializing in Allergen-Restricted Diets

• Allergy Grocer, www.allergygrocer.com
• Amy’s Kitchen, www.amys.com
• Arrowhead Mills, www.arrowheadmills.com
• Authentic Foods, www.authenticfoods.com
• Barbara’s Bakery, www.barbarasbakery.com
• Bob’s Red Mill Natural Food, www.bobsredmill.com
• Eden Foods, www.edenfoods.com
• Ener-G Foods, www.ener-g.com
• Gluten-Free Pantry, www.glutenfree.com
• Tofutti, www.tofutti.com

For more information, visit The Food Allergy & Anaphylaxis Network Web site at www.foodallergy.org.

Learning Objectives
After completing this continuing education course, the student will be able to:

1. Explain the difference between a food allergy and a food intolerance.

2. Explain the mechanisms of two types of true food allergy.

3. Identify various symptoms of food allergies and the tests most likely to reveal them.

4. List eight common allergy tests that should not be relied on for diagnosis.

5. List five American Academy of Pediatrics recommendations for infants with a strong atopic family history.

6. Discuss the pros and cons of various alternatives to cow’s milk.

7. List categories and essential characteristics of various types of infant formulas.

EXAMINATION

1. Food allergies affect how many U.S. children?
a. 25%
b. 6% to 8%
c. 12 million
d. 1% to 2%

2. Food intolerance involves the immune system’s response to an antigen.
a. True
b. False

3. Which of the following are credible methods for use in diagnosing immunoglobulin E (IgE)-mediated allergies?
a. CAP RAST (radioallergosorbent test)
b. Immunoglobulin G levels
c. Skin prick tests
d. Both a and c

4. How often does a positive skin prick or CAP RAST test correlate with a positive food challenge?
a. 10% to 15%
b. 30%
c. 40% to 50%
d. Always

5. A negative skin prick test indicates which of the following:
a. The patient definitely does not have an IgE-mediated food allergy.
b. The patient may have an IgE-mediated food allergy.
c. The patient needs to undergo further testing.
d. The patient definitely has a non–IgE-mediated food allergy.

6. Infants with a strong family history of atopic allergies should follow which recommendation?
a. Avoid breast-feeding
b. Exclusive breast-feeding for 12 months
c. Use of hypoallergenic formulas when breast milk is unavailable
d. Delay the introduction of solids until 8 months of age

7. As a toddler, which food allergens are the most difficult to avoid?
a. Shellfish and peanuts
b. Milk and fish
c. Egg and soybean
d. Milk and wheat

8. If a 2 year old has a cow’s milk protein allergy, he or she should not consume which of the following?
a. Amino acid-based formula
b. Goat’s milk
c. Hemp milk
d. Protein hydrolysate-based formula

9. What are the benefits of using products that are manufactured specifically for allergen-restricted diets?
a. Improved quality of life
b. Increased vitamin and mineral intake
c. Increased compliance with the dietary restriction
d. Both a and c

10. An unsupervised restricted diet can result in which of the following nutritional issues?
a. Poor growth
b. Vitamin D deficiency
c. Calcium deficiency
d. All of the above

TABLE:

 Comparison of IgE-Mediated and Non–IgE-Mediated Allergies

TABLE:

Symptoms Specific to Each Type of Allergy4

TABLE:

Infant Formula Categories, Characteristics, and Indications

References
1. Greer FR, Sicherer SH, Burks AW, American Academy of Pediatrics Committee on Nutrition, and American Academy of Pediatrics Section on Allergy and Immunology. Effects of early nutritional interventions on the development of atopic disease in infants and children: The role of maternal dietary restriction, breastfeeding, timing of introduction of complementary foods, and hydrolyzed formulas. Pediatrics. 2008;121(1):183-191.

2. Shuker M, Groetch M. In: Pediatric Manual of Clinical Dietetics, 2nd ed Update. Amorde-Spalding K, Nieman L, Eds. Chicago: American Dietetic Association; 2008.

3. American Partnership for Eosiniphilic Disorders. About EE. Available at: http://www.apfed.org. Accessed November 10, 2008.

4. Justinich CJ. IgE and Non-IgE gastrointestinal food allergy. Clinical Nutrition Week: A Scientific and Clinical Forum and Exposition. Orlando, Fla. January 29, 2005, to February 2, 2005.

5. Noimark L, Cox HE. Nutritional problems related to food allergy in childhood. Pediatr Allergy Immunol. 2008;19(2):188-195.

6. Sampson HA. Utility of food-specific IgE concentrations in predicting symptomatic food allergy. J Allergy Clin Immunol. 2001;107(5):891-896.

7. Agostoni C, Fiocchi A, Riva E, et al. Growth of infants with IgE-mediated cow’s milk allergy fed different formulas in the complementary feeding period. Pediatr Allergy Immunol. 2007;18(7):599-606.

8. American Academy of Pediatrics. Committee on Nutrition. Soy protein-based formulas: Recommendations for use in infant feeding. Pediatrics. 1998;101(1 Pt 1):148-153.

9. Hill DJ, Murch SH, Rafferty K, Wallis P, Green CJ. The efficacy of amino acid-based formulas in relieving the symptoms of cow’s milk allergy: A systematic review. Clin Exp Allergy. 2007;37(6):808-822.

10. Zutavern A, Brockow I, Schaaf B, et al. Timing of solid food introduction in relation to eczema, asthma, allergic rhinitis, and food and inhalant sensitization at the age of 6 years: Results from the prospective birth cohort study LISA. Pediatrics. 2008;121(1):e44-e52.

11. Agostoni C, Decsi T, Fewtrell M, et al. Complementary feeding: A commentary by the ESPGHAN Committee on Nutrition. J Pediatr Gastroenterol Nutr. 2008;46(1):99-110.

12. Fiocchi A, Assa’ad A, Bahna S, et al. Food allergy and the introduction of solid foods to infants: A consensus document. Adverse Reactions to Foods Committee, American College of Allergy, Asthma and Immunology. Ann Allergy Asthma Immunol. 2006;97(1):10-20.