Studies Show Peanut-Rich Diets During Pregnancy and Injection-Free Milk Immunizations May Help
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Reviewed By Louise Chang, MD
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March 18, 2008 (Philadelphia) — Peanut allergies among kids are on the rise, a new study shows, but several novel strategies show promise for stemming — even reversing — the tide.
Researchers studying mice found that by eating peanuts while pregnant and breastfeeding, new moms may lower the risk that their babies will be affected.
Meanwhile, another study suggests that kids can be immunized against potentially fatal peanut allergies — and without any shots. Swallowing small doses of peanut protein under a doctor's supervision helped to desensitize children with peanut allergy, the idea being to cut the risk of a reaction if they accidentally eat peanuts.
As for milk allergy, injection-free treatments may work there, too — and if not, other research suggests that four out of five kids who are allergic to egg, milk, or wheat may be able to safely start eating those foods by school age.
The research was presented here at the annual meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI).
Peanut Allergies on the Rise
About 2.2 million school-aged children have allergies to foods, with milk, eggs, peanuts, and tree nuts among the most common culprits.
Now, a new study suggests that peanut allergies among young schoolchildren have risen 35% over the past five years.
Reactions can range from mild to severe, and can even lead to anaphylaxis, a life-threatening condition characterized by difficulty breathing and loss of consciousness.
Researchers at McGill University in Montreal randomly surveyed parents of kids in kindergarten through third grade in 2000-2002 and 2005-2007. About 8,000 parents were studied in all, says Moshe Ben-Shoshan, MD, a fellow in the department of allergy and immunology.
Peanut allergies were confirmed by the researchers, typically through the use of skin prick tests.
Results showed that 1.8% of kids had food allergies in 2005-2007, up from 1.3% in 2000-2002.
Ben-Shoshan says that the new results offer a clearer snapshot of the trend than past studies, as allergies were confirmed with objective testing.
Can a Peanut a Day Keep Allergies Away?
Vivian Hernandez-Trujillo, MD, an allergist at Miami Children's Hospital, in Florida, says that pregnant women with allergies often ask what they can do to protect their babies from developing allergies "and we really don't know what advice to give."
As a step toward finding out, researchers at Mt. Sinai School of Medicine in New York City studied pregnant mice with peanut allergies.
Some of the mice were fed small amounts of peanut protein while they were pregnant and breastfeeding, the idea being to increase their tolerance to the nuts. The other mice were fed a normal diet.
After birth, the baby mice were given escalating amounts of peanut protein for five weeks in an effort to further sensitize them to peanuts. Doctors call this oral immunotherapy.
At the end of the study, the researchers "challenged" the pups with a larger serving of peanuts, to see if it would evoke an allergic reaction.
Almost all the babies born to mothers who ate a normal diet had allergic reactions, the study showed.
In contrast, only two of eight mice whose mothers ate a nut-rich diet during pregnancy and breastfeeding had allergic responses, and both were mild.
"The results are fascinating and thought provoking," says Hernandez-Trujillo, who moderated the session at which the studies were presented.
Peanut Oral Immunotherapy
The best way to avoid food allergies is, of course, to simply avoid the food.
But that's not as easy as it sounds and accidental ingestion is common, says Scott David Nash, MD, an allergist at Duke University.
For years, allergists have used immunotherapy, which includes the ubiquitous allergy shot, to combat allergies to insect stings and nasal allergies.
Nash's team tried another tactic: oral immunotherapy. They gave 20 children with known peanut allergy escalating doses of peanut protein in the form of a flour mixed into applesauce or other food. Once they reached a daily dose of 300 milligrams, about the equivalent of one peanut, they stayed on that dose for four to 11 months.
At the end of the study, Nash's team challenged the kids with a hefty serving of peanut flour. It contained nearly 8 grams of peanut protein, or the equivalent of more than 13 peanuts.
"Nineteen of 20 (95%) of the patients were able to ingest the full amount of the challenge, and most did not have any symptoms during the food challenge," he tells WebMD. A few participants broke out in hives.
One person, who developed hives and airway tightening after the full dose, was immediately and successfully treated with epinephrine.
Immune system changes from the start to the end of the study showed growing tolerance to the peanut protein, Nash adds.
The long-term goal is buildup of enough tolerance so the food allergy "goes away," says researcher Wesley Burkes, MD, chairman of the AAAAI program committee and a professor of pediatrics at Duke University, Durham, N.C. He also worked on the study.
"But for now we've shown that even though they have to keep eating the food, the chance of having an accidental allergic reaction is less," he tells WebMD.
More study is under way.
Milk Allergies Studied
Other researchers report that oral immunotherapy also appears to be safe and effective for treating cow's milk allergy in kids.
The study, done at Johns Hopkins, involved 11 young children and teens, aged 6 to 17, with proven milk allergies. They were randomly assigned to receive either escalating doses of milk protein in the form of powder mixed with water, or a placebo drink.
Once they reached a daily dose of 500 milligrams, about the equivalent of two cups of milk, they stayed on that dose for three to four months.
At the end of the study, the researchers gave the kids the 8,140-milligram challenge. Before the treatment, all 11 kids exhibited symptoms after ingesting 40 milligrams of milk protein. In contrast, one participant who finished the course of oral immunotherapy tolerated the entire 8,140 milligrams, the study showed.
"The results are very promising," says Burke, who also worked on this study. "The subset that received the milk powder could tolerate much more milk before they had a reaction by the end of the study."
Waiting Allergies Out
If all else fails, maybe parents can just wait their kids' allergies out. Japanese researchers report that more than 80% of kids with egg, milk, or wheat allergies became tolerant to these foods by their teenage years.
Researchers at the Shiga Medical Center for Children in Moriyama, Shiga, surveyed the parents of schoolchildren who had been diagnosed with allergies to egg, milk, or wheat before age 1.
The percentage of kids with allergies to those three items dropped over time — from 5.4% at age 7 to 3% at age 15, the study showed.
Not all the news was good: By age 15, these children were 10 times more likely to avoid other foods, most notably buckwheat, shellfish, and fruits, than teens who never had food allergies.
Burke says that researchers don't really know why kids can outgrow allergies.
What is clear is that children with food allergies should be regularly re-evaluated, he says.
And while the new research is exciting, people with food allergies — or their parents, in the case of young children — should stand by the tried and true, the experts say. Avoid foods you're allergic to. And carry an auto-injector such as EpiPen or Twinject — a syringe filled with epinephrine and encased in a self-injecting device that can be used anywhere, anytime, they say.
SOURCES: American Academy of Allergy, Asthma & Immunology Annual Meeting 2008, Philadelphia, March 14-18, 2008. Moshe Ben-Shoshan, MD, fellow, department of allergy and immunology, Mt. Sinai School of Medicine, New York City. Vivian Hernandez-Trujillo, MD, Miami Children's Hospital. Scott David Nash, MD, fellow, department of allergy, Duke University, Durham, N.C. Wesley Burkes, MD, chairman, program committee, AAAAI Annual Meeting 2008; professor of pediatrics, Duke University, Durham, N.C. T. Kusunoki, MD, Shiga Medical Center for Children in Moriyama, Shiga, Japan.
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