Battling peanut allergies
Allison Rush couldn’t trade lunches with the other kids in her elementary school. She had to skip the cake at birthday parties and couldn’t go trick-or-treating with her friends. Despite all the precautions, at age 7 she collapsed after eating a peanut-contaminated cookie baked by her class.
She was revived with a shot of epinephrine, the standard treatment for people with peanut allergies. “It was pretty scary,” the 16-year-old said recently. She now carries epinephrine with her wherever she goes and dines out only reluctantly. “I don’t eat at Chinese or Japanese restaurants, because they cook a lot with peanut oil,” the Boulder, Colo., resident said. “And it’s kind of hard to eat at restaurants I’ve never eaten at before.”
Such extreme vigilance may ultimately be unnecessary, not only for Allison but also for the estimated 1.5 million people in the United States who have peanut allergies. Researchers are devising new ways to detect, treat and prevent such allergies and, although most are still in development, they ultimately could save lives.
In highly allergic people, a fraction of a peanut -- one-sixtieth of the legume, in Allison’s case -- can cause a potentially fatal condition called anaphylaxis, in which airways in the lung constrict and the throat can swell shut. Peanuts cause more severe reactions than any other food item, says the American Academy of Allergy, Asthma and Immunology, resulting in 50 to 100 deaths each year.
Doctors recommend that anyone with a peanut allergy should carry an EpiPen, a portable injection of epinephrine, but most don’t. Some find it inconvenient, said Anne Munoz-Furlong, chief executive of the nonprofit Food Allergy & Anaphylaxis Network. That’s why thousands of people with peanut allergy end up in hospital emergency rooms, she added.
In a study that shows promise for these people, scientists reported last week that activated charcoal pills -- cheap, easy to take and already on the market -- may ultimately be used to stem anaphylactic reactions.
Dr. Peter Vadas, director of allergy and clinical immunology at St. Michael’s Hospital in Toronto, showed how an activated charcoal solution can prevent anaphylaxis. The solution is commonly used to treat poison victims, and some hospitals also use it to treat people with peanut allergies. Vadas’ laboratory study is the first to show how it may work.
In one experiment, activated charcoal effectively removed peanut proteins from mixtures of chocolate and vanilla ice cream. In another experiment, Vadas combined activated charcoal with a mixture of peanut proteins and applied it to the forearms of six people with peanut allergies. In mixtures of 200 milligrams of charcoal for every milligram of peanut protein, the subjects had no reaction to the proteins. Vadas said activated charcoal “acts like a sponge,” binding to poisons and carrying them out of the digestive system before they can do harm. His studies indicated that the compound treats peanut proteins the same way. And, he said, the charcoal may prevent secondary reactions that occur as lingering peanut proteins make their way through the digestive system.
Although activated charcoal is usually given as a drink, its most potent form, the pill version may work in a similar way. The more portable tablets have not been tested in people with peanut allergies, but Vadas said that, after further testing, they could be taken whenever people felt a reaction coming on. Dr. Donald Y.M. Leung, a pediatric allergist at National Jewish Medical and Research Center in Denver, said Vadas’ findings are of “immediate importance,” because “so many parents have activated charcoal at home to treat poisons.” Leung has long used activated charcoal to stem recurrent anaphylactic reactions in patients and said people could use the liquid compound at home to do the same.
Mac Hawley, who is allergic to peanuts and heads an investment firm in Evergreen, Colo., has taken activated charcoal solution as a participant in a separate study.
“The miracle of it is that the minute you eat activated charcoal -- and you’ve got to eat quite a bit of it -- wherever you are when you eat it, it stops the allergy right there,” Hawley said. “The reaction doesn’t go any further.”
Vadas’ results were published in the July issue of the Journal of Allergy and Clinical Immunology. Also in that issue, researchers at Mount Sinai School of Medicine in New York reported that a new test can better identify those with peanut allergies.
Most people discover they have the allergy with their first bad reaction and have it confirmed by a skin-prick or blood test performed by a doctor. But the tests don’t recognize peanut allergy in about half the people who say they have symptoms. In those cases, doctors conduct a test in which they closely monitor patients’ reactions to increasing amounts of a food allergen. Though highly accurate, such tests are time-consuming and expensive and put allergic people at risk of anaphylaxis.
The new procedure can measure previously undetectable blood levels of peanut-specific IgE, the immune system molecule that triggers allergic reactions when it binds to peanut proteins.
Hugh A. Sampson, lead author of the study, said the test can also be used to identify people who are mildly allergic and therefore likely to outgrow the allergy, which 20% of peanut-allergic children will do.
Sampson, a professor of pediatrics and immunobiology, and his colleagues are also in the early stages of creating a peanut vaccine using a genetically engineered peanut protein. In animal studies, the vaccine stopped peanut-sensitive mice from reacting to the legume altogether; further studies will show if the effects will be similar in humans.
Sampson said the vaccine may have even broader benefits. “If it’s as good in humans as it is in the mouse model, we’ll move on to other food allergies,” such as eggs and milk, he said.
Other reports in the journal showed that peanut butter isn’t as likely to trigger reactions as previously thought and that roasted peanuts may be particularly hazardous.
Research into peanut allergies, and how to prevent and treat them, are growing as public awareness grows along with the number of allergies. The Food and Drug Administration announced approval last month of a new type of drug that blocks IgE. Although approved for asthma, the drug will soon be tested as a way to increase tolerance to peanuts.
Allison Rush, who has participated in clinical trials of a similar drug, can now tolerate about six peanuts before experiencing an allergic reaction. “It makes me feel more confident. I don’t have to worry so much now,” she said.
Leung said that the latest developments are particularly good news because they’re of practical importance for people who now spend time every day steering clear of peanuts.
Sampson agreed. “If we really have a method that we could use to turn off allergic reactions to peanuts,” he said, “it’s huge news for people with peanut allergies.”
