Life-threatening peanut allergies have mysteriously been on the rise in the past decade, with little hope for a cure.
But a groundbreaking new study may offer a way to stem that rise, while another may offer some hope for those who are already allergic.
Parents have been told for years to avoid giving foods containing peanuts to babies for fear of triggering an allergy. Now research shows the opposite is true: Feeding babies snacks made with peanuts before their first birthday appears to prevent that from happening.
The study is published in the New England Journal of Medicine, and it was presented at the annual meeting of the American Academy of Allergy, Asthma and Immunology in Houston. It found that among children at high risk for getting peanut allergies, eating peanut snacks by 11 months of age and continuing to eat them at least three times a week until age 5 cut their chances of becoming allergic by more than 80% compared to kids who avoided peanuts. Those at high risk were already allergic to egg, they had the skin condition eczema, or both.
Overall, about 3% of kids who ate peanut butter or peanut snacks before their first birthday got an allergy, compared to about 17% of kids who didn’t eat them.
“I think this study is an astounding and groundbreaking study, really,” says Katie Allen, MD, PhD. She's the director of the Center for Food and Allergy Research at the Murdoch Children’s Research Institute in Melbourne, Australia. Allen was not involved in the research.
Experts say the research should shift thinking about how kids develop food allergies, and it should change the guidance doctors give to parents.
Meanwhile, for children and adults who are already allergic to peanuts, another study presented at the same meeting held out hope of a treatment.
A new skin patch called Viaskin allowed people with peanut allergies to eat tiny amounts of peanuts after they wore it for a year.
A Change in Guidelines?
Allergies to peanuts and other foods are on the rise. In the U.S., more than 2% of people react to peanuts, a 400% increase since 1997. And reactions to peanuts and other tree nuts can be especially severe. Nuts are the main reason people get a life-threatening problem called anaphylaxis.
In 2000, the American Academy of Pediatrics recommended that parents avoid feeding nuts to high-risk infants until the age of 3. Eggs were off limits until age 2 for these children, with cow’s milk delayed for at least a year. In 2008, they updated those guidelines, saying there wasn’t enough evidence to show that avoiding certain foods, like nuts, in the early years might prevent allergies. But the academy didn’t exactly endorse the idea of early introduction of these foods, either. And baby books, like the popular What to Expect series, still advise parents to keep peanuts, eggs, and milk off the menu for at least the first year.
Some experts say that advice is wrong.
“We probably did contribute to peanut allergy specifically because of the guidelines that were written in 2000,” says Rebecca Gruchalla, MD, PhD. She's the director of the Division of Allergy and Immunology at the University of Texas Southwestern Medical Center, in Dallas. Gruchalla wrote an editorial on the new study but was not involved in the research.
“Not only do we not need to delay, we actually need to introduce early in children that are at risk for developing peanut allergy,” she says.
A Snack Food Spurs a Study
In 2008, Gideon Lack, MD, a pediatric allergist at King's College in London, made a stunning observation. He found that the rate of peanut allergies among Jewish children in the U.K. was ten times higher than among Jewish kids living in Israel.
In Israel, a first food for many babies is a snack called Bamba, corn puffs coated with peanut powder -- essentially a cheese doodle made with peanuts.
But parents in the U.K., like those in the U.S., had been advised by doctors to steer clear of peanuts for babies.
Lack wondered if the early introduction to peanut protein in Israel might explain the difference in the rates of allergies between the two countries.
Lack believes the early feeding works because of something he calls the dual allergy theory. In cultures where peanuts are a dietary staple, peanut protein is everywhere, even in house dust.
He believes that the immune system is first introduced to peanut protein through the skin, especially if that skin is already cracked and inflamed, as it is in eczema.
“The system is seeing it and being alerted to it, especially in children with eczema,” Allen says.
But eating the protein introduces peanuts in a second way that teaches the immune system to tolerate and ignore them as harmless, she says.
Gathering Evidence
Lack designed a study to test his idea, a theory some of his colleagues quietly discounted.
“I was extremely skeptical about this because I felt there had to be other factors involved,” says Allen, who is running a large study of peanut allergies in Australia.
Lack looked for babies who were known to be at high risk for getting nut allergies because they were already allergic to another protein -- egg protein -- or they had eczema, a skin condition that’s closely linked to allergies.
He gave every child a skin test to see if they would react to peanut protein before they entered the study.
In skin testing, allergists scratch the skin with a little bit of the extract of allergen. If a red, irritated spot forms where the allergen was placed, it means a person is probably sensitive to it. The larger the red spot, the bigger the reaction a person is likely to have to the allergen if they eat or breathe it in.
Babies who had marked reactions -- they developed a red spot on their skin larger than 4 millimeters -- were kept out of the study for fear that it would be too dangerous for them.
The others, 640 in total, were randomly split into two groups. Parents in the first group were told to feed them peanut snacks -- either Bamba or peanut butter -- three times a week. The amount of peanut protein they were getting was relatively small -- the amount in about 24 peanuts -- spread over three weekly meals. (It’s not a good idea to feed babies whole peanuts because they’re a choking hazard.)
Parents in the second group were told to avoid peanut products for their babies.
‘Landmark’ Results
The findings were striking. After 5 years, the kids who ate peanut snacks on a regular basis were far less likely to be allergic to them than the group that didn’t.
Among children who were already mildly allergic to peanuts when they entered the study, 35% of those who avoided peanuts developed an allergy compared to roughly 11% who ate them.
Among those who started with a skin test result that showed they didn't have a peanut allergy, about 14% of kids who avoided peanuts became allergic to them compared to just 2% of those ate them regularly.
“It’s a major landmark study,” says Scott Sicherer, MD, a professor of pediatrics, allergy and immunology at Mount Sinai Hospital in New York City.
Cautions for Parents
Sicherer and other experts say parents shouldn’t be tempted to start feeding their babies foods that have peanuts in them, particularly if the child is at high risk of allergies or they have a parent with allergies or asthma.
“I don’t want the whole world to go out and start giving their 4-month-old peanut without being evaluated first if they are in that high allergy group,” Grunchalla says.
Before the kids in the peanut group started the study, she says, they first went through an oral challenge supervised by a doctor to make sure they could safely eat peanuts. Even kids who don’t have a worrisome skin test can still react to a food. That’s why the challenge was crucial before they tried the foods at home.
It’s also not clear whether children will continue to keep their tolerance to peanuts if they don’t eat them regularly.
For that reason, Lack is still following the kids in the study to see if the differences persist over time.
“That’s the key question. 'Has the immune system really been modified for life?' And we don’t know the answer,” Grunchalla says.
More Hope on the Horizon
Meanwhile, for children and adults who are already allergic to peanuts, there is little they can do except to avoid eating them. That can be hard, as peanuts can hide unsuspected in foods. Although food labels help, foods prepared at restaurants can be especially troublesome. Immunotherapy, or allergy shots, may not work for food allergies, and it can trigger very severe reactions.
Oral immunotherapy, where people build up tolerance by eating increasing bits of peanut in their doctor’s office, is also being tested. But it, too, can trigger scary reactions.
Now, though, scientists have figured out how to deliver immunotherapy through the Viaskin skin patch, and it seems to have fewer side effects.
The patch is about the size of a small round Band-Aid. People typically wear them on their backs and change them each day.
“This is a new way to deliver immunotherapy,” says study author Hugh Sampson, MD, a pediatric allergist at Mount Sinai School of Medicine. “It has a small amount of peanut protein on the patch, you wear that for the day, and during the day a small amount of their protein penetrates the skin.”
Certain skin cells, called Langerhans cells, pick up the protein and take it to the lymph nodes, where it teaches the immune system to ignore the protein.
In a study of 221 people, about half of those who wore the highest dose of the patch were able to boost their tolerance, compared to just 25% in the group that did not wear the patch.
At the end of a year, those on the high-dose patch were able to eat about four peanuts. That was ten times as much peanut as they were able to eat at the start of the study.
It won’t allow people with peanut allergies to start eating peanut butter and jelly sandwiches, Sampson says But it should protect them from having to worry about small amounts of contamination in foods, like the peanut-tainted cumin spice that’s the subject of a huge FDA recall..
The trial will continue, and he hopes that the longer people wear the patches, the more tolerance they’ll build.
If their results hold in a larger trial, Sampson says the company that makes the patch will file for FDA approval.
Brenda Goodman - WebMD
