A milk allergy is a food allergy, an adverse immune reaction to one or more of the protein constituents of milk from any animal (most commonly alpha S1- casein, a protein in cow's milk). The body manifests either an antibody-based immune response or a cell-based immune response to these allergens. Antibody responses are usually rapid and can involve anaphylaxis, a potentially life-threatening condition. Cell-mediated responses take hours to days to appear. A wide variety of foods can cause allergic reactions, but in the United States 90% of allergic responses to foods are caused by cow's milk, eggs, wheat, peanuts, tree nuts, shellfish, fish and soy. The Food Allergen Labeling and Consumer Protection Act (FALCPA) of 2004 requires that the label of a food that contains an ingredient that is or contains protein from these eight major food allergens declare the presence of the allergen in the manner described by the law. Milk is also on the mandatory labeling list in Japan. and the European Union. "Food allergen labelling and information requirements under the EU Food Information for Consumers Regulation No. 1169/2011: Technical Guidance" (April 2015).
DescriptionMilk allergy is a food allergy, an adverse immune reaction to a food protein that is normally harmless to the nonallergic individual. Milk allergy is a distinct from lactose intolerance, which is a nonallergic food sensitivity, due to not enough of the enzyme lactase in the small intestines to break lactose down into glucose and galactose.
Signs and symptomsThe effects of antibody-mediated allergy are rapid in onset, evolving within minutes or seconds. These allergies always arise within an hour of drinking milk; but can occasionally be delayed longer when eating food containing milk as an ingredient. The effects of non-antibody-mediated allergy is delayed; because it is not caused by antibodies, it can take several hours, or even up to 72 hours to produce a clinical effect. The most common symptoms for both types are hives and swelling, vomiting, and wheezing, with symptoms first arising in skin, then the GI tract, and less commonly, the respiratory tract. Milk allergy can cause anaphylaxis in about 1–2% of cases, which is a severe, life-threatening allergic reaction.
MechanismsConditions caused by food allergies are classified into three groups according to the mechanism of the allergic response:
- IgE-mediated (classic) – the most common type, manifesting acute changes that occur shortly after eating, and may progress to anaphylaxis
- Non-IgE mediated – characterized by an immune response not involving immunoglobulin E; may occur hours to days after eating, complicating diagnosis
- IgE and non-IgE-mediated – a hybrid of the above two types
DiagnosisDiagnosis is carried out by first doing a diagnostic elimination diet, skin prick tests, measuring IgE in blood, and conducting in-office food challenges. A double-blind, placebo-controlled food challenge is still the gold standard for the diagnosis for all food allergies, including milk allergies. A negative IgE test doesn't rule out antibody-based allergy (in the case of false negatives), or cell-mediated allergy. Therefore, double-blind, placebo-controlled food challenge is important to rule out this form of allergy.
PreventionThe main means of preventing an allergic reaction to milk is avoiding all dairy products. Milk from other species (goat, sheep...) should not be substituted for cow's milk, as milk proteins from other mammals are often cross-reactive. Dairy proteins can be found in breast milk, so nursing mothers should also abstain from dairy products. Probiotic products have been tested, and some found to contain milk proteins which were not always indicated on the labels. Milk substitute formulas are used to provide a complete source of nutrition for infants. These include soy-based formulas, hypoallergenic formulas based on partially or extensively hydrolyzed protein, and free amino acid-based formulas such as Neocate, EleCare, and Puramino. 'Milk' substitutes from soy, rice or almonds are not appropriate for infant feeding in lieu of breast milk or infant formula, as these are not nutritionally complete, lacking many essential vitamins and minerals.
TreatmentThe elimination diet should be tested every six months by testing milk-containing products low on the "milk ladder", such as fully cooked foods containing milk, in which the milk proteins have been denatured, and ending with fresh cheese and milk. Treatment for accidental ingestion of milk products by allergic individuals varies depending on the sensitivity of the person. An antihistamine such as diphenhydramine (Benadryl) may be prescribed. Sometimes prednisone will be prescribed to prevent a possible late phase Type I hypersensitivity reaction. Severe allergic reactions may require treatment with an epinephrine pen, i.e., an injection device designed to be used by a non-healthcare professionial when emergency treatment is warranted.
EpidemiologyIncidence and prevalence are terms commonly used in describing disease epidemiology. Incidence is newly diagnosed cases, which can be expressed as new cases per year per million people. Prevalence is the number of cases alive, expressible as existing cases per million people during a period of time. “Incidence and Prevalence” Advanced Renal Education Program (Accessed 17 October 2017). Milk allergies are usually observed in infants and young children, and often disappear with age (see Prognosis), so prevalence of egg allergy may be expressed as a percentage of children under a set age. Milk allergy affects between 2% and 3% of infants in developed countries. This estimate is for antibody-based allergy; prevalence of allergy based on cellular immunity is unknown.Lifschitz C, Szajewska H. Cow's milk allergy: evidence-based diagnosis and management for the practitioner. Eur J Pediatr. 2015 Feb;174(2):141-50. PMC 4298661 For all age groups, a review of fifty studies conducted in Europe estimated 6.0% for self-reported milk allergy and 0.6% for confirmed. National survey data in the United States collected 2005-2006 showed that from age six and older, the prevalence of serum IgE confirmed milk allergy was under 0.4%.
PrognosisGenerally, affected infants lose clinical reactivity to milk during early childhood or at latest by adolescence; around half the cases resolve within the first year and 80-90% resolve within five years.Caffarelli C, et al. Cow's milk protein allergy in children: a practical guide. Ital J Pediatr. 2010 Jan 15;36:5. Review. PMC 2823764 Milk allergy is found to be associated with increased hospitalization rates and steroid use among children with asthma. Between 13% and 20% of children allergic to milk are also allergic to beef.
ResearchDesensitization, which is a slow process of eating tiny amounts of the allergenic protein, until the body is able to tolerate more significant exposure, results in reduced symptoms or even remission of the allergy in some people and is being explored for milk allergy. This is called oral immunotherapy. Sublingual immunotherapy, in which the allergenic protein is held in the mouth, under the tongue, has been approved for grass and ragweed allergies, but not yet for foods.http://acaai.org/allergies/allergy-treatment/allergy-immunotherapy/sublingual-immunotherapy-slit/ Sublingual Therapy (SLIT) American College of Allergy, Asthma and Immunology A 2014 meta-analysis found oral desensitization for cow's milk allergy in children to be relatively safe and effective but found that further study was needed to understand the overall immune response to it, and questions remain open about duration of the desensitization.Martorell Calatayud C, et al. Safety and efficacy profile and immunological changes associated with oral immunotherapy for IgE-mediated cow's milk allergy in children: systematic review and meta-analysis. J Investig Allergol Clin Immunol. 2014;24(5):298-307. Free full text. There is research on probiotics as a means of treating milk allergy, but three reviews concluded that the evidence is inconsistent and cannot yet be recommended. As noted above, some probiotic products have been shown to contain milk proteins, not always indicated on the labels, and may cause an allergic reaction.
Society and cultureWhether food allergy prevalence is increasing or not, food allergy awareness has definitely increased, with impacts on the quality of life for children, their parents and their immediate caregivers. In the United States, the Food Allergen Labeling and Consumer Protection Act of 2004 causes people to be reminded of allergy problems every time they handle a food package, and restaurants have added allergen warnings to menus. The Culinary Institute of America, a premier school for chef training, has courses in allergen-free cooking and a separate teaching kitchen. Culinary Institute of America Allergen-free dining oasis comes to the CIA (2017) School systems have protocols about what foods can be brought into the school. Despite all these precautions, people with serious allergies are aware that accidental exposure can easily occur at other peoples' houses, at school or in restaurants. Food fear has a significant impact on quality of life. Finally, for children with allergies, their quality of life is also affected by actions of their peers. There is an increased occurrence of bullying, which can include threats or acts of deliberately being touched with foods they need to avoid, also having their allergen-free food deliberately contaminated.
- Food allergy (has images of hives, skin prick test and patch test)
- List of allergens (food and non-food)
- Milk soy protein intolerance