Milk Allergy

October 8, 2004 02:39:22 AM PDT, KidsHealth.org

Your baby’s screaming is driving you nuts! Is this normal fussiness? Or could it be a sign of something else?

Almost all infants experience irritability and sleeplessness at times. But if your bottle-fed baby seems excessively fussy much of the time, it could be due to an allergy to cow’s milk.

Most of us have heard of lactose intolerance (the inability to digest the type of sugar in milk), but there’s another milk-related problem that’s lesser known: cow’s milk protein allergy. Between 1% and 7.5% of infants are allergic to the proteins found in cow’s milk and cow’s milk-based formulas. About 80% of formulas on the market are cow’s milk-based.

What Is Cow’s Milk Protein Allergy?
Cow’s milk protein allergy (also called formula protein allergy) means that the infant (or child or adult) has an abnormal immune system reaction to proteins found in the cow’s milk used to make standard baby formulas. About 30% to 40% of infants who are allergic to cow’s milk are also allergic to the protein in soy formulas. The baby’s immune system “attacks” the proteins in the milk, resulting in symptoms of an allergic reaction.

Researchers don’t fully understand the causes of food allergies and why some children develop them and others don’t. However, according to Heidi Kecskemethy, a pediatric dietitian, “Studies have shown that breast-fed infants have a lower risk of developing allergies than those who receive cow or soy milk.” It is believed that in many cases, this type of allergy is triggered by a combination of genetically inherited factors and the early introduction of cow’s milk or soy protein into an infant’s diet.

Signs and Symptoms
Symptoms of cow’s milk protein allergy will generally appear within the first 6 months of life. An infant can experience symptoms of one or both of the two major types of formula allergy reactions – rapid onset or slower onset.

The rapid type of reaction comes on suddenly with symptoms that can include wheezing, vomiting, hives, anaphylaxis (a sudden and severe whole body reaction), angioedema (fluid collection in body tissues that causes swelling), and the eruption of itchy bumps on the skin.

The slower-onset reaction is the more common type. Symptoms may include loose stools (possibly containing blood), vomiting, irritability or colic, and failure to gain weight and grow normally. This type of reaction is more difficult to diagnose because the same symptoms may occur with conditions other than allergy. Most children will outgrow this form of intolerance by 2 years of age.

If an infant’s symptoms are due to lactose intolerance (a sensitivity to the carbohydrate in milk) and not protein intolerance, symptoms will include a swollen or enlarged abdomen, stomach pain, excessive gas, and diarrhea.

How Is It Diagnosed?
If you suspect that your baby’s distressed behavior is due to formula protein allergy, the first thing you should do is to arrange for a visit with your child’s doctor. Because the condition is often misdiagnosed and mistaken for normal fussiness, it’s important to rule out other problems and get a specific diagnosis.

An office visit to evaluate these symptoms may begin with the doctor asking you a few questions regarding your family’s history of food allergies or intolerance. Then a physical exam will be performed on your baby. Because some symptoms of protein allergy overlap with those of other illnesses, one or more lab tests may be done to help sort things out. Because no single lab test can accurately diagnose protein allergy, several tests may be performed.

  • A stool test may be done to help determine the cause of the symptoms. Stool samples of children with protein allergy often test positive for blood. Stools of children with lactose intolerance tend to be acidic and contain undigested sugar.
  • An allergy skin test may also be done. If an allergy is present, a small amount of milk protein inserted under the surface of the skin with a needle may produce a reaction – a red, raised spot called a wheal. This test is not perfect, however. Many milk-allergic infants will not show a reaction, and many older children who are not milk-allergic will show a positive skin test result.

Treatment
If your baby is found to have the rapid-onset type of cow’s milk protein allergy, switching to a soybean-based formula may be a successful treatment. Soy-based formulas contain the proteins found in soybeans rather than those found in cow’s milk. Most of the same vitamins and minerals found in cow’s milk- based formulas are also found in soy-based formulas, making the nutritional value of the two formulas basically equal. Only 8% to 15% of infants with this type of allergy have an adverse reaction to soy formulas. If the switch to soy formula doesn’t stop the symptoms, the infant usually will be switched to a hypoallergenic formula. The protein in hypoallergenic formulas has been specially treated to make it less likely to trigger an allergic reaction. About half of all infants with the more common slow-onset type of milk allergy are also allergic to soy formulas, in which case a hypoallergenic formula is recommended. Unfortunately, hypoallergenic formulas can be up to three times as expensive as standard cow’s milk or soy formulas. There are three major types of hypoallergenic formulas available:

  • whey-based hydrolysate formulas, in which the whey in the cow’s milk protein has been broken down or “predigested,” making it less allergenic than the whole proteins in regular formulas
  • casein hydrolysate formulas, which contain smaller protein fragments and amino acids (the basic building blocks of proteins).
  • amino acid-based infant formulas, which contain protein in its simplest form, may be recommended if your baby’s condition doesn’t improve with a switch to one of the hydrolysate formulas above

(Note that formulas labeled as partially hydrolyzed protein formulas are NOT considered hypoallergenic.)

It is possible that your child’s doctor may suggest switching from cow’s milk-based formula to exclusive breast-feeding.

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