Who could forget the tragic "peanut butter kiss of death" headlines about a Canadian teen who, it was widely reported, died of anaphylactic shock related to a peanut allergy. Her boyfriend had spread a smear of peanut butter on toast some nine hours before the fatal kiss.
Well, the teenager did, in fact, die -- but little else of that story proved true. What wasn't initially reported was that the girl had asthma and had spent hours at a party where a lot of guests were smoking. A coroner's report some months after her death reported that she stopped breathing at the moment of the kiss because of cerebral anoxia, a lack of oxygen to the brain, which was triggered by a severe asthma attack.
But with the initial erroneous story, a lot of damage was done. Parents around the world panicked that the mere stale whiff of a peanut could be fatal, and people began to doubt the life-saving treatment for such a severe peanut allergy, an injection of epinephrine. Some physicians resorted to smearing peanut butter on a child's arm to prove to parents that the touch or smell or proximity of a peanut was not life-threatening. One study showed that children with peanut allergy exposed to open peanut butter jars had no bad reaction. However, grinding peanuts can release particles into the air, and a person with allergies could have a reaction to the particles -- though usually not a serious anaphylaxis.
Only eight foods account for 90 percent of food allergies: cow's milk, eggs, tree nuts, peanuts (peanuts are legumes, not true nuts), fish, shellfish, soybeans and wheat. But those foods are our staples, and nearly 4 percent of children in the United States -- three million youngsters -- have one or more of those allergies.
Even the best estimates we have on the prevalence of food allergies are a little squishy. When a team of researchers reviewed multiple studies, they found some significant differences in studies that depended on patients or parents' self-reports and those that used more objective measures, like skin prick tests or serum tests for specific foods. The analysis ended up estimating food allergies in at least 1 percent to 2 percent of the population, but less than 10 percent. It's pretty apparent that we have a lot of research to do to pin down the extent of the problem, but there's no denying that a lot of children are affected.
Some of them will outgrow it, but for others it will be a lifelong problem. Symptoms range from tingling around the mouth to hives and, in rare and extreme cases, anaphylactic shock. About 9,500 children each year are admitted to hospitals for some form of food allergy.
But death by peanut is extremely rare. While estimates range from about 150 to 200 deaths a year from peanut allergies, reporting is spotty and not required, and the Centers for Disease Control and Prevention officially documents only 13 deaths (including six adults) between 1996 and 2006.
Nuts: the Good and the Bad
Nuts are easy, they're fun, they're crunchy. Peanuts are the most popular nut, present in the diets of 73 percent of Americans, followed by almonds, cashews, pecans, walnuts and pistachios. We put them in salads and entrees and sprinkle them on our cereal, yogurt and hot fudge sundaes. They add fiber and protein to our diets and are a satisfying snack. Because they can help lower cholesterol, many nuts carry the American Heart Association's heart-shaped seal of approval on their packaging, and are an important component of the heart-healthy Mediterranean diet.
But self-reports of peanut allergies are rising. One study found that, between 1997 and 2002, the number of children with peanut allergies doubled, though reports did not increase among adults. Still, some three million Americans -- adults and children -- may have such allergies. And since the consequences from peanuts can be most severe from minimal ingestion, the problem is serious.
Who Is at Risk
People with a family history of asthma or peanut allergy are at higher risk for the allergy themselves. And when someone has asthma along with an allergy to peanuts, the risk of anaphylactic shock increases.
Recent research suggests that babies who arrive via cesarean section are five times more likely to develop a range of allergies, and while it's still theoretical, it may be because those infants are not exposed to bacteria in the birth canal. Such exposure affects the immune system and is in line with the theory called the hygiene hypothesis: that early exposure to microorganisms might boost the immune system.
Theories, Old and New, for the Increase in Food Allergies
For a time, the hygiene hypothesis was at the forefront of possible explanations. That theory holds that our modern obsession with extreme cleanliness, including antibacterial soaps and hand sanitizers, leave our children with fewer tools to fight off germs. Excessive cleanliness, experts reason, interrupts the normal development of the immune system, resulting in an increase in allergies. But food allergies are also rising in the developing world in places such as the favelas of Brazil where children may be exposed to less than stellar sanitary conditions.
A more recent theory involves epigenetics. Science is discovering that our bodies, through chemical signals, can actually switch our genes on or off, depending on environmental exposures. Maybe common pollutants, like tobacco smoke, can change our genes and make youngsters more vulnerable to food allergies.
And while we don't have definitive answers, recent research may begin to alter when we recommend introducing foods to infants. One recent study showed that introduction of rice cereal before the age of 4.5 months, for example, increased allergic reactions, while introducing wheat, rye, oats or barley cereals at five months decreased allergic reactions to those grains.
Dealing With Peanut Allergies
For now, the only treatment for peanut allergy is strict prevention by avoiding all peanuts, or rapid injections of epinephrine when peanuts are accidentally eaten. The fear of accidental ingestion by children who might have allergies has changed everything from school lunches to birthday party treats. In many schools, parents can no longer send home-baked treats to classrooms because they may inadvertently contain peanut products. Only pre-packaged goods with labels proclaiming the product peanut-free are allowed. An industry has grown up promoting products for children, including T-shirts instructing all that this child cannot eat peanuts.
The issue of food allergies has gone to the highest levels of our government. In a ruling under the Americans with Disabilities Act, a university reached an agreement with the Department of Justice to provide allergy-free meals in school cafeterias.
Incremental Dose Therapy
One small study presents some hope that we can help people get over their peanut allergies. Researchers tested 40 people with peanut allergies, ages 12 to 37, by first testing their tolerance to a small dose of peanut powder. Then they gave half the group a small daily dose of the powder, gradually increasing the dose; they gave the other half of the group a placebo. After 44 weeks, those given the real peanut powder could increase their symptom-free consumption from 3.5 milligrams at the start of the study to 496 milligrams. After 68 weeks, their tolerance went up to 996 milligrams.
And, as the New York Times Magazine reported recently, Stanford University researcher Kari Nadeau, M.D., Ph.D., is experimenting with children who have multiple food allergies by desensitizing them simultaneously for all the foods they cannot tolerate, starting with even smaller microdoses. She's had considerable success, but even when children begin to tolerate foods that once threatened their lives, they must eat minimal amounts of the foods every day in order to maintain the tolerance.
This type of desensitization therapy is very new, and should only be done with medical guidance in a carefully controlled setting. Don't ever try this at home.