What is Cow’s Milk Protein Allergy (CMPA) & What Causes It?

What is Cow’s Milk Protein Allergy (CMPA)?

There are two basic types of cow’s milk protein: casein (found in what curdles) and whey (found in what doesn’t curdle).¹ Babies with CMPA might be allergic to one or both of these types of proteins.²

Like other allergic reactions, a cow’s milk protein allergy is caused by an immune system reaction to the proteins found in cow’s milk and dairy products.³ Your baby’s immune system views the proteins in cow’s milk as harmful, which triggers and an allergic reaction.¹ Cows milk protein allergy results in two types of reactions: IgE-mediated (immediate reaction) and non-IgE-mediated (delayed reaction).

The Difference Between CMPA and Lactose Intolerance

Understanding the difference between a food allergy and a food intolerance can help you understand whether or not your infant is experiencing a cow’s milk protein allergy or lactose intolerance. A food intolerance isn’t a reaction of the immune system. Instead, a food intolerance is gastrointestinal discomfort after eating certain foods. Food intolerances can cause discomfort, but are not life threatening.

Lactose intolerance is an inability to breakdown and absorb lactose, a sugar in milk, but it’s not an allergic reaction to protein or any other component of cow’s milk.³ Lactase is the enzyme responsible for digesting lactose and deficiency in this enzyme causes lactose intolerance.⁴ Thankfully, it's rare for babies to be born with lactase deficiency, and lactose intolerance is not commonly found in infants.³  When it does appear, it’s called congenital lactase deficiency, which renders infants unable to break down lactose in breast milk or formula and may result in severe diarrhea.⁴ Babies born prematurely may have a lactose intolerance called developmental lactase deficiency, but this condition lasts only a short time after birth.

For help decoding the difference, look to the symptoms—if there are symptoms beyond gastrointestinal issues, it’s likely an allergy.

Symptoms of lactose intolerance include:⁴

• Gas
• Bloating
• Abdominal pain
• Nausea
• Diarrhea

Symptoms of cow’s milk protein allergy may include any of the above, plus: ^2,3

• Itching around mouth or throat
• Swelling of and around the mouth and face
• Wheezing or coughing
• Shortness of breath
• Hives
• Blood in the stool
• Reflux
• Colic

Anaphylaxis is a clear and alarming sign that your little one has an allergy rather than an intolerance.² If your baby has difficulty breathing, extreme swelling of the face or throat or appears to be losing consciousness, call for first responders or head to the closest emergency department immediately.²

Talking with Your Doctor About Your Baby and CMPA

Tests are on the menu if you see a potential allergic reaction to milk or formula. If you suspect your baby has cow’s milk protein allergy, talk to your doctor to better understand whether your baby is experiencing CMPA or lactose intolerance and how to care for your little one.

When you visit the pediatrician, it’s helpful to give the doctor a complete picture of what’s happening with your infant. Keep a log of your baby’s behaviours, feeding times, sleeping times, type of formula given (if any), and anything that concerns you like spitting up, rashes, gas and diarrhea. Review this log and mention your top concerns to the doctor.

Similarly, let the doctor know if you or anyone in your baby’s family has a food allergy, or a family history of issues like hay fever, eczema or asthma.⁵ If these issues are present, your baby may have an increased risk of CMPA.⁵

The following questions may also be useful during your visit to the doctor.

• What dietary changes should I make if I am nursing a baby who has cow’s milk protein allergy?
• What formulas do you recommend for a baby who has cow’s milk protein allergies?
• How soon after switching to a hypoallergenic formula should my baby’s cow’s milk protein allergy symptoms improve?
• What is the long-term outlook for my baby if he or she has cow’s milk protein allergy? Will he or she always have allergies?

The most important thing is that your concerns are addressed by your doctor and that you feel confident about caring for your infant and managing their CMPA at home.

Caring for a Baby with CMPA

If your baby is displaying symptoms of cow’s milk protein allergy, your doctor may suggest eliminating cow’s milk protein from your infant’s diet.^3,5 Fortunately, there are lots of healthy dietary options available for a baby with CMPA.

Options for Breastfed Babies

When you nurse, some of the nutrients from the foods you eat are passed along to your baby in breast milk. When you consume a food that contains cow’s milk protein (such as milk products), your baby may be exposed to cow’s milk protein.^2,3 But this is not a reason to stop nursing! Breast milk provides the best nutrition for your baby. Instead, your doctor may suggest eliminating all dairy products from your diet.^2,3 Milk and products such as yogurt and cheese are obvious sources of dairy, but other foods like breads, cereals, and salad dressings can contain milk too.² You will have to read labels carefully for hidden milk ingredients like casein and whey. You should also be on the lookout for these other names for cow’s milk while reading nutrition labels:

• Alpha-lactalbumin
• Beta-lactoglobulin
• Caseinate (ammonium, calcium, magnesium, potassium, sodium)
• Delactosed or demineralized whey
• Lactalbumin and lactalbumin phosphate
• Lacto-serum
• Skim milk powder, skim milk powder solids
• Whey and whey protein concentrate

Thankfully, while the following ingredients may have names that sound like cow’s milk components, they are dairy free and are safe for consumption by nursing mothers who are breastfeeding infants with a CMPA:

• Calcium and sodium lactate
• Calcium and sodium stearoyl lactylate
• Cocoa butter
• Cream of tartar
• Oleoresin

Also, you may need to be strictly dairy-free for two weeks or longer before your baby’s allergic reactions subside.³ Do this only under a doctor’s recommendation and supervision. You may want to also talk to a dietitian about finding alternative sources of calcium and other nutrients to replace what you were getting from dairy products.³

If your baby’s food allergy does not resolve after a trial of eliminating cow’s milk protein from your diet, your doctor may suggest eliminating soy from your diet as well.⁵ Many babies who are allergic to cow’s milk protein are also allergic to soy protein.⁵

Options for Formula-Fed Infants

It's the cow's milk protein in most infant formulas that causes allergic reactions in babies with CMPA. Hypoallergenic formulas are specially formulated to reduce an infant's risk of allergic reactions to cow's milk protein. The two types of hypoallergenic formulas recommended for infants with cow's milk protein allergy include extensively hydrolyzed formulas and amino acid-based formulas for babies who have more severe allergies.

• Extensively Hydrolyzed, Hypoallergenic Formulas
  Proteins are made of numerous amino acid building blocks linked together to form long chains. The immune system of a baby with cow's milk protein allergy mistakenly sees some cow's milk protein chains as harmful, and allergic reactions occur as it tries to fight them off. Imagine breaking apart these long protein chains into lots of smaller chains. That's what the cow's milk protein in Nutramigen^® A+^® with LGG^® looks like. The cow's milk protein chains in extensively hydrolyzed, hypoallergenic formulas like Nutramigen^® A+^® with LGG^® are so thoroughly broken into tiny pieces (what's known as hydrolyzed) that the immune systems of most infants with cow's milk protein allergy no longer recognize the milk protein as a threat.³
• Amino Acid-Based Formulas
  Most babies with cow’s milk protein allergy do well on an extensively hydrolyzed formula, however, in some severe cases, an amino acid formula (such as PURAMINO A+^®) may be recommended.³

Unlike routine infant formulas where hundreds of amino acids link to form long chains of cow's milk protein, or extensively hydrolyzed formulas where fewer amino acids link to form small protein chains, amino acid-based formulas contain no cow’s milk protein.³ Amino acid-based formulas are made with the building blocks of proteins: amino acids. An amino acid-based formula like PURAMINO A+^® contains no cow's milk protein. Many doctors prescribe amino acid-based formulas for infants who experience severe allergic reactions (such as serious breathing difficulties and anaphylactic shock) to cow's milk protein. Amino acid-based formulas may also be recommended for infants with multiple allergies to foods, including cow's milk protein, soy, eggs, wheat, peanuts, tree nuts, and fish.

Products Not Recommended for Infants with an Allergy to Cow’s Milk Protein

With so many infant formulas on the market, it can be difficult to figure out which one is best for a baby with cow’s milk protein allergy. You should always follow your doctor’s advice. In general, though, the following formula types are not recommended for infants with cow’s milk protein allergy:

• Partially Hydrolyzed Formulas
  These might seem like a good option for a baby with cow's milk protein allergy because they're designed to be tummy friendly. But even though the cow's milk protein chains in these formulas are partially broken down or hydrolyzed, they're still big enough to cause allergic reactions in infants with cow's milk protein allergy (that means these formulas are not hypoallergenic).³
• Lactose Free Formulas
  Lactose is a naturally occurring carbohydrate, or sugar in milk.⁴ Lactose-free formulas are cow’s milk-based formulas with the lactose removed. Lactose-free formulas still contain intact cow’s milk protein and are therefore not appropriate for a baby with cow’s milk protein allergy.
• Soy-Based Formulas
  It might seem like a good idea to switch to a formula that isn't made from dairy, such as one made with soy protein. However, many babies with cow's milk protein allergy also are allergic to soy protein.^3,5
• Other Milk Sources
  Formulas made with goat's or sheep's milk are not recommended for infants with cow's milk protein allergy because their milk proteins are very similar to cow's milk protein and can cause allergic reactions.^3,5 Other milks made from soy, almonds, coconut, and rice are not nutritionally complete and should not be given to infants.⁵

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