With continued consumption, children's tolerance can improve, study shows
THURSDAY, Aug. 27 (HealthDay News) -- Children who are allergic to milk may be able to overcome their allergy by drinking increasingly higher doses of milk, a new study finds.
In 2008, researchers from Johns Hopkins Children's Center in Baltimore reported that children with a severe milk allergy could "retrain" their immune systems to tolerate milk and other dairy products by gradually consuming increasingly higher doses.
In the current study, researchers followed up with 18 children aged 6 to 16 whose symptoms had eased or gone away during the previous study.
When 13 of the 18 children returned to the clinic up to 17 months later, six continued to have no reaction after drinking 16 ounces of milk, twice the highest amount tested in the earlier study. Seven children had mild reactions, including itchy mouth, hives, sneezing and stomachache after drinking less than 16 ounces. One child needed medications for a cough, the researchers noted in a news release from Johns Hopkins.
The researchers also followed up with three children who could not drink more than 2.5 ounces at the end of the prior study. All three continued to drink milk daily with only mild reactions, and two were able to drink more than 2.5 ounces with few problems, the study authors found.
The study was published in the Aug. 10 online issue of the Journal of Allergy and Clinical Immunology.
One key to keeping the allergy at bay seems to be regular consumption of milk and dairy products, according to the study.
"We now have evidence from other studies that some children once successfully treated remain allergy-free even without daily exposure, while in others the allergies return once they stop regular daily exposure to milk," said senior author Dr. Robert Wood, director of Allergy & Immunology at Johns Hopkins Children's Center. "This may mean that some patients are truly cured of their allergy, while in others the immune system adapts to regular daily exposure to milk and may, in fact, need the exposure to continue to tolerate it."
The researchers also tested for milk allergy using skin-prick testing, a standard food allergy test. Between eight and 15 months post-study, seven children had no reactions. Blood levels of milk IgE antibodies, which indicate allergy, slowly decreased, while IgG4, an antibody that indicates immunity to an allergen, rose.
The study authors also found that the prevalence of reactions continued to decline over time.
As part of the study, children and their parents kept daily logs of milk and dairy consumption and recorded symptoms, such as hives, abdominal pain, sneezing and cough. For the first three months, drinking milk triggered reactions nearly half of the time. During the next three months, milk triggered reactions 23 percent of the time, while some children reported no reactions.
Milk allergy is the most common food allergy. In those who are allergic, milk proteins cause the immune system to overreact, bringing a cascade of symptoms that can range from hives, itching, swelling and vomiting to anaphylaxis in the most severe cases.
Three million U.S. children have at least one food allergy, according to the U.S. Centers for Disease Control and Prevention.
The Food Allergy & Anaphylaxis Network has more on food allergies.
-- Jennifer Thomas
SOURCE: Johns Hopkins Children's Center, news release, Aug. 18, 2009
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