Clearing up doubts.. How are cow's milk protein allergy and lactose intolerance different?

Phyathai 3

6 Min

01/04/2020

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Clearing up doubts.. How are cow's milk protein allergy and lactose intolerance different?

“Breast milk” is the sole food for infants under 6 months old. Breast milk is rich in various nutrients in amounts suitable for infants. However, some infants need supplemental cow’s milk, and for older children and adults, cow’s milk is also a source of protein, calcium, and vitamins to help strengthen the body. But in some cases, consuming milk causes abnormal symptoms in the body. Not all symptoms are due to cow’s milk allergy; some may just be adverse reactions after consuming cow’s milk.

 

This article will explain the differences between cow’s milk protein allergy and lactose intolerance, which is not a milk allergy but can cause abnormal symptoms after milk consumption…

 

Lactose Intolerance

Actually, this condition is not a milk allergy but only an adverse food reaction after milk consumption. It occurs due to abnormal digestion of lactose in milk. Lactose is a sugar found abundantly in the milk of mammals. Human milk contains up to 7%, while cow, goat, sheep, and camel milk contain about 4%. This sugar has a large molecule and must be digested by the enzyme lactase before absorption through the intestinal mucosa. Lactase is produced only by the small intestine lining. Normally, infants who consume milk as their main food have a high amount of lactase enzyme. As they grow and switch to rice as the main food, lactase production decreases but remains sufficient for digestion, so no abnormal symptoms occur.

 

In people with lactose intolerance, the small intestinal cells produce less or no lactase enzyme, called lactase deficiency. Those with this condition experience the following symptoms after milk consumption:

  • Bloating from gas, frequent flatulence, and rumbling sounds in the abdomen
  • Abdominal pain around the navel or lower abdomen
  • Nausea and vomiting, often seen in older children and adolescents
  • Watery diarrhea with bubbles

 

Causes of Lactase Deficiency Divided into 3 Groups

  1. Congenital lactase deficiency caused by genetic abnormalities
  2. Genetic lactase deficiency (Late onset lactase deficiency, Primary lactase deficiency) is common among Asians, South Americans, Africans, and Native Americans. Symptoms usually appear in older children and adults because infants still have high lactase levels, which decrease with age. Even with continuous milk and milk-containing food consumption, lactose digestion becomes insufficient, causing symptoms.
  3. Secondary lactase deficiency occurs after infections or chronic inflammation of the small intestine, such as after rotavirus infection, common in children under 5 years old. Rotavirus damages the small intestinal lining cells, causing cell death and shedding, leading to insufficient lactase production. After recovery and mucosal repair, lactose digestion returns to normal.

 

How to Diagnose Lactose Intolerance?

  • Direct method: measuring lactase enzyme in the intestinal mucosa by inserting an intestinal catheter with a capsule to cut the mucosa and measure lactase enzyme levels
  • Indirect method: measuring hydrogen levels in the breath or self-testing by observing symptoms after milk consumption. This can be done at home by fasting overnight, then drinking a large glass of milk (300-500 ml) in the morning and fasting for another 3-4 hours while observing and recording symptoms. Symptoms may appear as soon as 1 hour or up to 3 hours after milk consumption.

 

Treatment of Lactose Intolerance

For congenital lactase deficiency or genetic abnormalities, synthetic lactase enzyme may be necessary along with avoiding milk or milk products containing lactose.

 

For patients with temporary lactase deficiency, it is recommended to avoid milk containing lactose or consume half the usual amount of regular formula milk and gradually increase. For severe symptoms, choose soy milk, lactose-free cow’s milk formula, or yogurt, which contains microorganisms that partially digest lactose.

 

For breastfed infants, mothers should express the foremilk, which is high in lactose, before feeding the hindmilk. When symptoms improve, normal formula milk can be introduced in small amounts and gradually increased to allow the intestines to adjust.

 

Understanding Cow Milk Protein Allergy

Cow milk protein allergy occurs when the body has an immune reaction to proteins in cow’s milk through various allergic mechanisms. Symptoms can affect multiple systems and vary in severity depending on the allergic mechanism and individual severity. Symptoms usually appear within 1-3 hours, days, or weeks after milk consumption. In exclusively breastfed infants, cow milk protein allergy can occur through breast milk because the infant’s immune and digestive systems are not fully developed.

 

Symptoms and Signs of Cow Milk Protein Allergy by System are as follows:

  1. Skin: urticaria, acute subcutaneous swelling, atopic dermatitis
  2. Respiratory system: runny nose, dry cough, nasal congestion, snoring, wheezing, asthma, Heiner syndrome
  3. Gastrointestinal system: swollen lips, vomiting, acute watery diarrhea, chronic mucus and bloody stools
  4. Severe acute systemic allergic reaction (Anaphylaxis)

 

Diagnosis of Cow Milk Protein Allergy

  • History taking and physical examination are the most important parts of diagnosis
  • Oral food challenge test by observing patient response after avoiding and then consuming cow’s milk. For breastfed infants, mothers should avoid cow’s milk. If symptoms improve after avoidance, reintroduce cow’s milk after 4-8 weeks to test again.
  • Skin prick test or blood test for cow’s milk protein-specific IgE antibodies. These tests are not performed on all suspected cases because positive results depend on the allergic mechanism involved.

 

How to Treat Cow Milk Protein Allergy?

Treatment includes managing symptoms along with nutritional therapy, which should be guided by a physician.

  1. Provide food without cow’s milk or cow milk products as ingredients
  2. Provide nutritious and safe food
  3. After the patient is at least 1 year old and symptoms have improved for at least 6 months, consider oral food challenge tests every 6 months
  4. Choosing milk for treating cow milk protein allergy in infants depends on age, allergy type, and severity:
    • Infants and young children exclusively breastfed
      • Continue breastfeeding and have the mother avoid cow’s milk, cow milk products, and foods containing cow milk protein
      • Ensure the mother receives adequate calcium (800 mg/day) from diet or supplements
      • If symptoms do not improve, reconsider other diagnoses or possible allergies to other foods
      • If the mother cannot avoid cow’s milk, consider giving the infant a formula designed for cow milk protein allergy
    • Infants and children fed mixed milk
      • Choose milk without cow milk protein to replace the mixed milk the infant or child is receiving, considering symptom severity, patient age, cost, availability, and taste

 

Most Cow Milk Allergies Resolve on Their Own

Typically, cow milk protein allergy occurs within the first year of life, and symptoms improve until complete resolution as the child grows, with 81-95% outgrowing it by age 5. Additionally, cow milk protein allergy may be the starting point for other allergic diseases such as asthma and allergic rhinitis.

References
1. The Royal College of Pediatricians of Thailand, The Thai Pediatric Gastroenterology and Hepatology Association, The Thai Pediatric Nutrition Club, The Thai Allergy, Asthma and Immunology Association. Clinical Practice Guidelines for the Management of Cow Milk Protein Allergy.
2. Professor Dr. Wandi Worawit. Review Article: Lactose Intolerance. August 12, 2012.
http://www.pthaigastro.org/Document/rf0qed550cxcpq45jtxtsn45Lactose_Intolerance.pdf


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