What are the causes of milk sensitivity other than lactose intolerance?

From the Guidelines

Milk sensitivity beyond lactose intolerance is most commonly due to cow's milk protein allergy (CMPA), which affects approximately 2-3% of infants and young children, and requires strict avoidance of milk proteins to prevent symptoms such as skin reactions, gastrointestinal issues, and respiratory symptoms, as well as severe reactions like anaphylaxis 1.

Definition and Diagnosis

Milk sensitivity, other than lactose intolerance, is primarily caused by an immune response to proteins in cow's milk, such as casein and whey proteins. This condition is known as cow's milk protein allergy (CMPA) and is distinct from lactose intolerance, which is a non-immunologic adverse reaction due to the inability to digest lactose 1. The diagnosis of CMPA requires documentation of a clinical history of a food allergic reaction, and testing may include food-specific IgE tests and/or skin prick tests 1.

Symptoms and Management

Symptoms of CMPA can include skin reactions (hives, eczema), gastrointestinal issues (vomiting, diarrhea, abdominal pain), respiratory symptoms (wheezing, coughing), and in severe cases, anaphylaxis. For those with CMPA, complete avoidance of milk proteins is necessary, and infants may need specialized formulas such as extensively hydrolyzed formulas or amino acid-based formulas 1. Adults and older children should read food labels carefully to avoid milk proteins, which may be listed as casein, whey, lactalbumin, or other dairy derivatives.

Key Considerations

• CMPA is an immunologic reaction, whereas lactose intolerance is a non-immunologic adverse reaction 1.
• CMPA requires strict avoidance of milk proteins, whereas lactose intolerance can be managed with lactase enzyme supplements 1.
• Most children outgrow CMPA by age 3-5, but some may have lifelong sensitivity 1.
• For those with suspected milk protein allergy, consultation with an allergist is recommended for proper diagnosis and management 1.

Recent Findings

Recent studies have highlighted the importance of distinguishing between food allergies and intolerances, and the need for precise diagnosis and management of CMPA 1. Data science technologies have revealed increased IgG antibody reactivity to epitopes present in foods, including casein and cow's milk, in patient populations 1. However, it is essential to note that a positive allergy test result in the absence of clinical symptoms is not adequate to make a diagnosis of food allergy 1.

From the Research

Milk Sensitivity Other Than Lactose Intolerance

Milk sensitivity, other than lactose intolerance, can be caused by various factors, including:

• Allergens in the form of proteins, such as casein and whey proteins, found in cow's milk 2
• Milk processing techniques, like homogenization and pasteurization, which can alter the molecular structure of milk fat and whey proteins, making them potential allergens 2
• The balance between caseins and whey proteins in cow's milk, which can determine its allergenicity 3
• The type of beta-casein present in milk, with A1 beta-casein being associated with cows' milk intolerance due to the release of beta-casomorphin-7, which activates μ-opioid receptors in the gastrointestinal tract and body 4

Symptoms and Diagnosis

Symptoms of milk sensitivity can range from mild to severe and may include:

• Diarrhea, as seen in a murine model of atopy where mice were orally sensitized to native cow's milk or modified cow's milk with a casein/whey protein ratio of 40:60 3
• Abdominal pain, which has been positively associated with stool consistency in participants consuming A1 beta-casein type cows' milk 4
• Increased gastrointestinal transit time and production of inflammatory markers, such as myeloperoxidase, as observed in rodent studies 4
• Severe symptoms, including anaphylaxis, which can occur in adult cow's milk allergy patients, with low eliciting doses starting from 0.3 mg CM protein 5

Treatment and Management

Treatment and management of milk sensitivity may involve:

• Strict exclusion of nutrient-rich milk and other dairy products from the diet, which can put children with cow's milk allergy at higher nutritional risk 2
• Regular nutritional monitoring and the inclusion of protein and mineral-rich supplements as a substitute for cow's milk 2
• Management of animal genetics and milk processing to produce non-allergenic milk by inactivating allergic proteins 2
• Further research on the role of A1 beta-casein in milk intolerance and the potential benefits of consuming milk containing A2 beta-casein instead 4