Cow's milk allergy is the most common childhood food allergy.Reuters reports that according to a new JACI study, 75% of children with cow's milk allergy will be able to tolerate it if it is heated extensively.
Children who outgrow their milk allergy have milk-specific IgE antibodies directed against conformational epitopes; those with persistent milk allergy also had IgE antibodies directed against specific sequential epitopes. High temperature destroys conformational epitopes and some children with milk allergy would tolerate extensively heated (baked) milk products.
"Children who have outgrown their milk allergies still have milk-specific antibodies, but the specific milk proteins that trigger this reaction can almost entirely be destroyed through exposure to high temperatures.
The majority (75%) of children with milk allergy tolerated heated milk.
If these findings are confirmed by other studies, the approach to diagnosing and managing children with milk allergies should change, the authors conclude. "Allowing ingestion of heated milk products will dramatically improve the quality of life for the majority of subjects with milk allergy by vastly increasing the variety of food products they are able to consume."
The Reuters title mentions "warm" milk but in fact the milk used in the study was extensively heated.
What is the prognosis in milk allergy?
Milk allergy usually occurs within the first year of life, and 60 to 75% of children undergo remission by age 2 years. By age 3 years, 85-90% can tolerate milk. Approximately 68% of milk-allergic children can tolerate extensively heated milk. Most children with milk and egg allergy tolerate extensively heated forms of these foods http://goo.gl/Buwu
In children, 85% of cow’s milk, egg, wheat, and soy allergy resolves by five years. In contrast, only 20% of children “outgrow” their peanut allergy, and only 9% of tree nut-allergic patients do so.
What is the most common food allergen in children?
(A) Gal d (egg)
(B) Tri a 19 (wheat)
(C) Mal d 1 (apple)
(D) Gly m (soy)
(E) Ara h (peanut)
(F) Bos d (milk)
(G) Api g 4 (celery)
Answer: F.
8 top allergens account for 90 percent of food allergies. Specific IgE levels (sIgE) that predict the likelihood of passing an oral food challenge are shown in the figure. (click to enlarge the image).
Who will "outgrow" food allergy? It depends on the epitope
Each food is composed of many proteins and these proteins have multiple areas, termed epitopes, to which the immune system can respond. Epitopes that are dependent upon the folding of the proteins are called conformational epitopes. Epitopes that are not dependent upon folding are called linear epitopes.
A linear epitope oftens means a more prolonged allergy which is “stable” and persistent. A conformational epitope (egg, milk) often means a mild, transient allergy.
30-50% of infants allergic to cow milk protein will also be allergic to soy protein. These infants should be given protein hydrolysate formula. 5% of infants with hypersensitivity to cow milk formula will also react to hydrolysate formula and will require elemental formula.
Hydrolysate formulas are enzymatically hydrolyzed and contain charcoal-treated casein or whey. Whey or "milk plasma" is the liquid remaining after milk has been curdled and strained.
References:
Most children with milk allergy tolerate warm milk. Reuters.
Tolerance to extensively heated milk in children with cow's milk allergy. JACI, 7/2008.
Reintroduction of Cow's Milk in Milk-Allergic Children: Safety and Risk Factors. Int Arch Allergy Immunol. 2008 Jan 18;146(2):156-161.
Child with perioral rash upon milk ingestion; prognosis. Ask the Expert. AAAAI, 2009.
Eating baked goods that contain milk may help children "outgrow" milk allergy http://goo.gl/ca3FU
Challenge to baked milk - casein IgE <0.7 kUA/L is a favorable prognostic factor for tolerance of baked milk http://goo.gl/OAiiY
Rare, medium, or well done? Effect of heating on food protein allergenicity http://goo.gl/Z4LbX - It definitely affects milk and egg products.
Milk allergy resolution calculator from CoFAR http://bit.ly/U6TkNS - Mobile version: http://bit.ly/U6TmFn
Image source: Wikipedia, GNU Free Documentation License.
