Cow's milk protein and other allergies

Is my baby allergic to cow’s milk protein and other foods that I eat?

Some babies are allergic to cow’s milk protein. They may also be allergic to certain solid foods or to foods in breast milk, which contains bits of protein from the mother’s diet. Allergies can cause a range reactions, including facial swelling, hives, itching, vomiting, diarrhea, slow growth, or bloody stools (poop). The most common foods that cause allergic reactions are cow’s milk, eggs, tree nuts, peanuts, fish, seafood, soy, and wheat. Cow’s milk protein allergy has been found in about 1% of children. If mothers are breastfeeding an allergic baby, their health-care providers may ask them to remove one or more foods from their diet. If the offending agent cannot be identified or eliminated, mothers may need to stop breastfeeding and switch to using a special infant formula. Families may have to remove some solid foods from the baby’s diet. Many caregivers worry about their baby having an allergy and allergy diagnoses have been increasing dramatically from around 2005 as has the promotion and use of expensive non-allergic infant formula. 

A) Food allergies in babies

Some babies have allergic reactions to particular food items (allergens) that are present in:

  • Food their mothers eat, small bits of which enter breast milk (Picariello 2016; Picariello 2019; Zhu 2018).
  • Infant formula.
  • Solid foods.

Cow’s milk protein allergy is the most common allergy and eggs are the second-most common. Most estimates suggest that about 1-2% of babies are allergic to cow’s milk protein  (Nwaru 2014). Babies given infant formula in hospital or shortly after birth may be more likely to be allergic to cow’s milk protein.

Other allergens may include (Sackesen 2019):

  • Tree nuts
  • Peanuts
  • Sesame
  • Fish 
  • Seafood
  • Soy
  • Wheat 

Food allergies are different from lactose intolerance, which is not an allergy.

Managing allergies can be difficult because:

  • Tests may be inaccurate.
  • Research on prevention and treatment is still emerging.
  • Health-care providers’ advice varies (Pascual Pérez 2018).
  • Specialists can be difficult to find or expensive.
  • Guidelines used for their diagnosis and treatment may be influenced by commercial interests (Munblit 2020). 

Please consult your health-care providers if you believe your child has food allergies or is at high risk of them.

B) Types of allergic reactions

There are three main groups of allergies based on how the body reacts to the allergen. One involves activation of the IgE antibody (IgE-mediated) and the other causes activation of other parts of the immune system (non-IgE-mediated). The third category is mixed (IgE- and non–IgE-mediated) and activates both systems. Each group can produce a range of reactions.

1) IgE-mediated  

This type of allergy develops within hours of exposure to the allergen. Babies with IgE-mediated allergies may have one or more of the following:

  • Hives or swelling of the skin, mouth or throat (acute urticaria or angioedema)
  • Tummy problems including nausea, vomiting, pain, or diarrhea
  • Breathing problems including a runny nose, sneezing, wheezing, shortness of breath, or asthma
  • Tearing or itching of the eyes
  • Swelling and itching of the mouth (oral allergy syndrome)
  • Low blood pressure, dizziness, shock, death.

2) Non-IgE-mediated 

Non-IgE-mediated can cause several illnesses including (ABM 2011).

a) Food Protein–Induced Allergic Proctocolitis

Food Protein–Induced Allergic Proctocolitis (FPIAP) can caused blood-streaked stools (poop), mucous, or foam in stools. Babies may develop low blood iron levels if the bleeding is not stopped. It is the most common member of this group. 

b) Food Protein–Induced Enterocolitis Syndrome

Food Protein–Induced Enterocolitis Syndrome (FPIES) can cause repeated vomiting shortly after meals. During these episodes, the baby's blood pressure may drop quickly, they may be pale or sleepy, have diarrhea, or lose excess fluids. This is not common.

c) Food Protein–Induced Enteropathy

Food Protein–Induced Enteropathy (FPE) is uncommon in exclusively breastfed babies. They may have diarrhea, vomiting, or grow slowly.

3) Mixed IgE- and non–IgE-mediated

a) Eczema

Eczema is an itchy skin rash that is different from the normal rashes of newborn babies. Eczema that is severe or difficult to treat may be caused by a food allergy. 

b) Eosinophilic disease

Eosinophils are a type of blood cell. Eosinophilic disease is caused by the presence of these cells along with inflammation of the swallowing tube (esophagitis), stomach (gastritis), or bowel (colitis).   Babies may vomit, refuse to eat, or grow poorly.

C) Treatment of food allergies

Treatment of food allergies involves managing the symptoms and preventing further episodes by eliminating the allergen. If babies are receiving breast milk, health-care providers may ask mothers to remove certain allergen-containing foods from their diet. If the baby has started solid foods, certain ones may need to be stopped.

IgE-mediated allergies are most likely to respond to dietary changes. Non-IgE-mediated allergies can be more difficult to diagnose and manage (Bath-Hextall et al. 2009; Gordon et al. 2018; Meyer et al. 2020). 

It can take up to four weeks for the baby’s allergic reaction to settle down once the allergen has been removed. Some allergies will resolve in childhood but others can continue into adulthood (Abrams and Sicherer 2016).

1) Cow’s milk protein allergy

For breastfeeding mothers whose babies are allergic to cow's milk protein, removing all dairy from their diet can be difficult because dairy is found in many processed foods. A mother who is breastfeeding a baby with a cow’s milk protein allergy must avoid foods that include:

  • Cow’s milk and related products (skim milk, buttermilk, curds, whey, cream, sour cream, and milk solids)
  • Milk products (cheese, yogurt, and butter)
  • Margarine that contains dairy
  • Lactose, which can be contaminated with cow's milk protein
  • Proteins found in milk (caseinate, casein, lactalbumin)

Cow’s milk proteins can enter the breast milk within one hour of the mother consuming it. Levels peak between four and twenty-four hours (Burris 2020). One study (Matangkasombut 2017) reported one type of cow’s milk protein remained in breast milk at seven days after a single dose. If a mother accidentally consumes cow’s milk protein and the baby is allergic, depending on the severity of the baby’s reactions, she may consider expressing her milk and supplementing the baby with a milk the baby can tolerate.

Mothers who choose to avoid eating dairy need to ensure that their diet provides enough calcium and vitamin D.

Many babies will outgrow this allergy during childhood (Wood 2003).

2) When considering stopping breastfeeding

If the baby is unable to tolerate breast milk, mothers may be advised to undertake a trial of one of two types of non-allergenic infant formula designed for allergic children. They should be encouraged to maintain their milk supply by expressing. If the symptoms do not quickly clear with non-allergenic formula, the baby's diagnosis should be reconsidered and the mother may wish to resume breastfeeding. 

Mothers who choose to stop breastfeeding should ensure their baby can accept and tolerate non-allergenic infant formula. These formulas taste bitter and some older babies refuse to drink them. Mothers also need to ensure they can afford such products, as they are very expensive, and that weaning is an acceptable option. Some babies can tolerate soy-based infant formula.

D) Over-diagnosing babies

1) Risks of over-diagnosing food allergies

Parents tend to over-diagnose food allergies. One study (Eggesbø 1999) found that 35% of parents surveyed believed their child was reacting to some type of food and another (Nwaru 2014) found that 14% of parents reported their baby had a cow's milk protein allergy. However, the actual number of affected babies is around 1% Crying, vomiting, and rashes, which are normal and common, are frequently blamed on cow's milk protein allergy.

It is very important to have a proper diagnosis before eliminating certain foods and food groups. Eliminating them without a proper diagnosis can:

  • Result in more time spent shopping and preparing special meals.
  • Result in poor maternal nutrition (Boyce 2010).
  • Result in the baby missing some nutrients.
  • Result in increased use of infant formula and early weaning.
  • Be costly.
  • Increase the risk of a true allergy by delaying exposure to certain foods 

2) Promotion of food allergy diagnosis by infant formula manufacturers

The popularity of allergic diagnoses since the early 2000s has been helped along by the promotion of infant formula for allergic babies. As would be expected, sales of these expensive products has increased many-fold during this time.   

One example of such promotion is the role of infant formula manufacturers in the development of guidelines to diagnose and manage cow's milk allergy. One study (Munblit 2020) found that of nine cow's milk allergy guidelines published between 2012 and 2019:

  • Seven suggest considering cow's milk allergy as a cause of common infant symptoms.
  • The guidelines give relatively little consideration to breastfeeding support or promotion and pay much attention to maternal dietary exclusions and specialized infant formula use.
  • Three guidelines were directly supported by infant formula manufacturers or marketing consultants.
  • Eighty-one percent of all guideline authors reported a conflict of interest with infant formula manufacturers.

The authors conclude:

"Recommendations to manage common infant symptoms as cow's milk allergy are not evidence based, especially in breastfed infants who are not directly consuming cow’s milk. Such recommendations may cause harm by undermining confidence in breastfeeding."


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