What is cow milk allergy?
Cow milk allergy (CMA) is a reaction to cow milk that results from a hypersensitive immune response to one or more milk proteins. Symptoms of cow milk allergy can be skin rash, wheezing, vomiting, diarrhea, constipation and distress^1.

Milk is the most common cause of food allergy² affecting a minimum of 2-3% of infants². However symptoms suggestive of cows' milk allergy may be present in up to 15% of babies¹, highlighting the importance of getting an accurate diagnosis.

Allergy or intolerance?
Lactose intolerance should not be confused with milk allergy.

• A food allergy, such as cow milk allergy, involves a reaction, immediate or delayed, of the immune system to the protein in a particular food¹.
• Food intolerance differs in that the reaction does not involve an immune response¹. For example lactose intolerance occurs because of the body inability to break down the lactose in milk, causing bloating, abdominal pain and diarrhea⁵.

Lactose intolerance should not be confused with milk allergy.

Common food allergens
Most food allergy occurs in the first two years of life⁸. Common food allergens include:

• cow milk
• soy
• egg
• peanuts and tree nuts
• wheat
• fish⁶ and shellfish.

Although uncommon, even babies fed solely on breast milk* may react against food proteins from the mother’s diet which can find their way into her milk⁴.

* In rare cases, babies suffer allergic reactions despite being breastfed⁴. These are not reactions to the breast milk itself – they are reactions to proteins from the mother’s diet passing into the milk. It is possible to control these symptoms whilst continuing to breastfeed but seek medical attention. DO NOT stop breastfeeding without careful consideration of the social, nutritional and financial implications, as it may be difficult to reverse this decision. DO NOT restrict the mother’s diet, unless under the supervision of a dietitian, as over-restriction of the mother’s diet may be harmful to mother and child.

Most milk allergies in children disappear by the age of 3-5 years old whereas some allergies (e.g. nuts) tend to last for life⁸.

Symptoms of cow milk allergy
Most babies with cow milk allergy develop symptoms within the first few months of life. It is rare for symptoms to begin after the age of 12 months¹.
Most babies with cow milk allergy will have two or more symptoms¹:

• 50-70% have skin symptoms, e.g. eczema
• 50-60% have stomach/gut symptoms, e.g. vomiting
• 20-30% have breathing symptoms, e.g. wheezing.

The type of symptoms that occur with milk allergy depend on whether or not the reaction to milk is rapid or slow in onset:

• Rapid-onset reactions – these reactions appear quickly, one minute to an hour after having small amounts of milk. Symptoms can be severe and include: vomiting and hives⁷.
• Slow-onset reactions – these reactions are more common. Symptoms develop more slowly over several hours or days and are associated with larger intakes of milk. Symptoms may include: bloody stools, vomiting and diarrhea, colic and irritability, skin rash and failure to gain weight⁸.

Obtaining a diagnosis
It is important to obtain a correct diagnosis for milk allergy. Parents should consult a GP if milk allergy is suspected and request a referral to a specialist (e.g. Pediatric Allergy Specialist) if appropriate.

Management of cow milk allergy
The recommended management approach to cow milk allergy is to completely avoid cow milk protein. Milk is an important food for infants, so cutting it out from a baby’s diet may put them at risk of poor growth. If a milk allergy is diagnosed, the healthcare professional can prescribe a hypoallergenic formula, such as an amino-acid based formula (AAF) or an extensively hydrolyzed formula (eHF), that is easy to use, palatable, will provide rapid relief of symptoms and enables optimal growth and development.

Hypoallergenic formulas

Amino acid-based formulas (AAF)
The development of amino acid-based formulas is an important step forward in providing safe and effective nutrition for infants with cows' milk allergy¹⁰.

AAFs:

• provide rapid relief of vomiting and diarrhea in 3 days¹¹
• produce guaranteed symptom relief in 14 days¹²
• promote optimal growth¹³
• are suitable for highly allergic infants¹⁴

Extensively hydrolyzed formulas (eHF)
Extensively hydrolyzed formulas contain cows' milk proteins in smaller fragments. EHFs have reduced allergenicity compared to cow milk¹².

They are considered hypoallergenic and can offer relief in children with mild to moderate milk allergy¹⁵

• eHFs reduce the prevalence of eczema, inconsolable crying and infantile colic¹⁶.

Formulas not suitable for the management of cow milk allergy

Soy
Soy-based infant formulas should not be used for the dietary management of milk allergy in infants under the age of six months. , . According to an independent scientific committee that advises the Department of Health, soy-based infant formulas are not routinely recommended because of the high content of phytoestrogens (compounds that mimic the action of the female hormone estrogen) found in soy, which could pose a risk to the long-term reproductive health of infants, . There is also cross-reactivity between cow milk protein and soy protein, which means that some infants allergic to cow milk will also be allergic to soy .

Sheep and Goat milk
Sheep milk and goat milk are not suitable for the dietary management of milk allergy as these can also cause an allergic reaction in infants with cow milk allergy.
Partially hydrolyzed formula also has no role in the management of milk allergy as they contain intact proteins which can trigger allergic reactions.
‘Milks’ based on cereals, grains and legumes (e.g. oat milk, rice milk, pea milk) are unsuitable for infants with milk allergy because they are nutritionally inadequate.

References

1. Høst A. Cow milk protein allergy and intolerance in infancy. Pediatr Allergy. Immunol .1994;5:1-36
2. Niggemann B et al. Prospective, controlled, multi-center study on the effect of an amino acid based formula in infants with cow's milk allergy/intolerance and atopic dermatitis Pediatr Allergy Immunol. 2001;12:78-82 .
3. Sicherer SH. Review: Food Allergy. Lancet . 2002;360:701-710.
4. Høst A et al. Dietary products used in infants for treatment and prevention of food allergy Arch Dis Child . 1999:81;80-84.
5. National Institutes of Health, National Institute of Allergy and Infectious Diseases, An overview: Food allergy. NIH Publication No. 04-5518. 2004.
6. Wood RA. The natural history of food allergy. Pediatrics. 2003;111:1631-1637.
7. Hill DJ et al . Clinical Manifestations of cows' milk allergy in childhood. II. The diagnostic value of skin tests and RAST . Clinical Allergy. 1988;18:481-490.
8. Sampson HA. Update on Food Allergy . J Allergy Clin Immunol . 2004;113:805-19.
9. Cafferelli C et al. Determination of allergenicity to three cow's milk hydrolysates and an amino-acid derived formula in children with cow's milk allergy. Clin Exp Allergy. 2002;32:74-79.
10. de Boissieu D, Dupont C. Allergy to extensively hydrolyzed cow milk proteins in infants: Safety and duration of Amino acid-based formula. J Pediatr. 2002;141;27 1-3.
11. De Boissieu D Matarazzo P et al . Allergy to extensively hydrolyzed cow milk proteins in infants : Identification and treatment with an amino acid-based formula. J Pediatr, 1997 ; 131 : 744-747.
12. Vanderhoof JA, Murray ND et al . Intolerance to protein hydrolysate infant formulas : An under recognised cause of gastrointestinal symptoms in infants. J Pediatr, 1997 ; 131 : 741-744.
13. Isolauri E et al. Efficacy and safety of hydrolyzed cow milk and amino acid-derived formulas in infants with cow milk allergy. J Pediatr. 1995;127:550-7.
14. Hill DJ, Heine RG et al . The Natural history of intolerance to soy and extensively hydrolyzed formula in infants with multiple food protein intolerance J Pediatr. 1999;135;1.
15. Cafferelli C et a.l Determination of allergenicity to three cow's milk hydrolysates and an amino-acid derived formula in children with cow's milk allergy. Clin Exp Allergy. 2002;32:74-79.
16. Verwimp JJ, Bindles JG et al. Symptomatology and growth in infants with cow's milk protein intolerance using two different whey-protein hydrolysate based formulas in a Primary Health Care setting. Eur J Clin Nutr, 1195;49(Suppl1): S39-S48.
17. ESPGHAN Committee on Nutrition. Soy Protein Infant Formula: A Commentary by the ESPGHAN Committee on Nutrition. JPGN 2006; 42:352-61.
18. CMO's update 37.Department of Health , UK . January 2004.