Surprising facts about food allergies and babies

Food allergies, we're told, are on the march. Last month, Newsweek featured a cover story with a child wearing a gas mask while holding a peanut butter and jelly sandwich in one hand, and a carton of milk in the other. Here's a sample from the somewhat overheated story: "It is hard to fathom how the joys of childhood--a peanut-butter sandwich, a warm chocolate-chip cookie, a cold glass of milk--can send a tiny body into battle mode. How just one bite can make the throat itch, the lips swell, the stomach clench in agony."

Of course, children with serious allergies need special precautions. But the media often pushes the panic button without educating or reassuring the majority of healthy families. Thus, knowing the following--especially for parents of healthy infants--might help ease the anxiety around food allergies:

In general, food allergies are uncommon and usually not very dangerous. Here's a surprising fact: The most common food allergy among children under 3 years old isn't to peanuts, fish, or shellfish. It's to milk. Roughly 2.5 percent (about 1 in 40 kids) are allergic, making the condition twice as common as egg allergy and three times as common as peanut allergies.

Fortunately, most affected infants aren't in serious danger, because food allergies have a wide range of severity. Moreover, most food allergies from infancy disappear over a few years. The most common symptoms aren't acute breathing problems or swelling--which terrifies parents--but an annoying scaly rash called atopic dermatitis. In fact, the Archives of Internal Medicine in 2001 estimated that only 1 in 3 million people have potentially fatal allergies to food. (In comparison, potentially fatal penicillin and insect sting allergies are hundreds of times more common.) And while any death from food allergy is one too many, today only about 200 Americans die each year from them, which is about the same number struck by lightening. Thus, sudden death from food allergies is rare.

But aren't peanut allergies in particular increasing rapidly? It's one of the more dangerous allergies, since the reactions are usually worse than a rash. But it's not clear--despite what you may be seeing in the media--that it's really rising. The only study using actual lab testing for it was in the Isle of Wight, and showed a slight increase from 6 to 13 cases in separate groups of about 1,200 children in 1989 and 1996, but this variation is within the range of random chance. In 2003, the Journal of Allergy and Clinical Immunology suggested that rates among the youngest children increased from 0.4 percent to 0.8 percent during two separate phone surveys in 1997 and 2002. However, the overall rate including people of all ages was unchanged at 0.6%. Most importantly, among the families surveyed in 2002, the rate among kids under 5 years was essentially the same as children 6 to 10 years old (0.9% vs. 0.8%), which suggests there was no sudden increase.

Diagnosing food allergies properly is hard, and many children with suspected allergies don't really have them. In surveys, almost 25 percent of parents believe their children have food allergies, but only 4 to 7 percent are substantiated by formal testing. That means that most suspected allergies may be nonexistent. Unfortunately, some parents self-diagnose allergies based on vomiting or rash after their babies eat certain foods, and don't seek medical care. That's a problem, since a 2003 study found that children told they had a severe food allergy had more anxiety and felt more physically restricted than those with diabetes.

The "gold standard" test is a blinded food challenge, where a child is fed either the suspected food or a placebo in a clinical setting to see if a reaction occurs. But because of the time and expense of the test, it's not often done. The alternatives--blood and skin-prick tests--can be imprecise. According to a 2001 study from Clinical and Experimental Allergy, for example, only 1 in 4 children with positive skin tests (that is, those who develop a small hive when injected with a tiny dose of peanuts) had positive food challenges.

Bottom line: Don't assume your child has a food allergy unless a board-certified allergist or pediatrician with excellent allergy experience confirms the diagnosis.

You don't need a special diet to prevent allergies in your child, especially if you don't have a strong family history of food allergies. First of all, avoiding certain foods during pregnancy and withholding foods from infants does no good in healthy infants. Further, it's not clear whether "high-risk" infants (those with a strong family history) benefit either. The best study of this practice, published in the Journal of Allergy and Clinical Immunology in 1995, showed that an extremely strict maternal elimination diet coupled with delayed introduction of allergenic foods to kids had no impact on allergy symptoms by the time a high-risk child was 7-years-old.

For unclear reasons, the American Academy of Pediatrics (AAP) (see addendum below) still warns pregnant and nursing mothers to "consider eliminating eggs, cow's milk, fish, and perhaps other foods from their diets while nursing." But in 2006, a systematic review in the Archives of Pediatrics and Adolescent Medicine concluded, "Maternal avoidance of allergenic foods during lactation, particularly milk, egg, and peanut, has been studied extensively without conclusive results."

What about holding off on some foods until a child is older, which the AAP recommends for high-risk children? In fact, says Anne Munoz-Furlong, a researcher and the founder of the Food Allergy and Anaphylaxis Network, there is debate about whether delaying exposure to foods may do more harm than good. (This "hygiene hypothesis" suggests that overly sterile environments promote allergies.) Many Chinese and Israelis, for example, begin eating peanut extracts in infancy, and allergy rates seem lower there. And the 2006 evidence review agrees there is "little evidence" to delay foods, and that European allergy societies make no such recommendation.

Next, while breast-feeding is great for many reasons, it may not reduce allergies in healthy children. In 2004, an international consortium of allergists reviewed 92 prior studies and concluded breast-feeding and delaying solid food had no impact on allergies in infants with no family history of food allergy. Among children who are not breast-fed, also, there is no consistent benefit from using expensive "hydrolyzed" formulas to reduce allergies.

Bottom line: In general, very little that a parent can do affects a child's chance of food allergies.

Addendum: After this article was written in December 2007, the American Academy of Pediatrics revised their guidelines, and no longer recommend that women avoid allergenic foods during pregnancy.  For full details, see the AAP's revised policy statement by clicking here.