Cow Protein Allergy

Cow's Milk Protein Allergy (CMPA) affects between 2 and 7 percent of all human infants, although most children will grow out of the allergy by the time they're 5. CMPA can cause stomach upset, irritability, loose stools and skin rash, and in rare cases even life-threatening allergic reactions. Most commercial infant formulas are made from cow's milk, so treating CMPA in infants requires switching the baby onto alternate formulas or breast milk.

Causes

• Like all allergies, CMPA is caused by the body's immune system mistakenly interpreting a substance as an unwanted invader. The body kicks in with a variety of unpleasant symptoms designed to wipe out the invader. It's that immune response that makes people feel so miserable when they experience an allergic reaction. Breastfed infants have a lower risk of developing CMPA than formula-fed babies, but researchers still aren't clear on why some children react and others don't.

Symptoms

• The most common form of CMPA, known as "slow onset," doesn't show symptoms until seven to 10 days after a person has consumed milk. Symptoms include vomiting, loose or bloody stools, refusing to eat, general irritability and skin rash. People with rapid-onset CMPA will experience a reaction immediately after drinking cow's milk, with symptoms including all of the above as well as swelling, wheezing and hives. Rarely,a life-threatening anaphylactic reaction to cow's milk can lead to severe breathing problems and a dangerous drop in blood pressure.

Diagnosis

• CMPA can be challenging to diagnose. The "gold standard" for diagnosis, according to a report in the October 2007 issue of the Archives of Disease in Childhood, is an end to symptoms when a person is taken off cow's milk and a return of symptoms when cow's milk is briefly reintroduced later under a doctor's supervision. Skin-prick tests aren't as effective in diagnosing CMPA as they are for other types of allergies.

Treatment

• Infants diagnosed with CMPA will need to be either breastfed exclusively or switched onto special formula. Some will do well on soy-based formula, but others may have a sensitivity to soy. For those infants, doctors recommend extensively hydrolyzed formula that uses a "pre-digestion" process to break down the problem protein. Children with extreme sensitivity may need to go on an amino-acid formula, which breaks proteins down to their simplest form.

Considerations

• Nutritionists caution against substituting goat's milk or nut milk for infants with CMPA. Breastfeeding provides the best nutrition for infants and the least risk of CMPA, but in some cases the breastfed baby of a mother who eats a significant amount of dairy products can develop the condition. While the incidence of CMPA is still relatively rare, up to 15 percent of infants will experience at least some adverse reaction from cow's milk.