Why are food allergies on the rise

By Barbara C. Bourassa, Quality Health News

It's a sad fact in today's world: Food allergies are much more prevalent than in years past. When I was growing up, the only person I knew with a food allergy was my brother. If he ate any shellfish containing iodine, such as lobster or crabs, he broke out in hives.

Today, food allergies have become so common that many elementary schools and summer camps have had to ban homemade treats in order to prevent food made with nuts from entering the classroom. And the medical statistics back up this increase: The number of people suffering from food allergies has doubled over the past 10 to 20 years, according to Robert Wood, MD, director of the division of allergy and immunology at Johns Hopkins University School of Medicine in Baltimore, Md.

Specifically, the number of children with peanut allergies increased twofold between 1997 and 2002, according to data from the American Academy of Allergy Asthma and Immunology.

Why have allergies increased?

There are many theories that explain this increase, but most doctors admit they don’t really know the answer. For starters, all allergic diseases appear to be increasing, says Wood in the November 2006 issue of Pediatric Asthma, Allergy, & Immunology. Over the last 10 to 20 years, the number of children suffering from asthma has also increased significantly, he notes.

Research has also shown that the number of people with food allergies is increasing in developed and developing countries, but not in underdeveloped areas.

One explanation for this phenomenon as it relates to peanut allergies may be the way the nuts are prepared. Most peanuts in the U.S. are dry-roasted at high temperatures, and experts say the high temperatures may change the protein structure of the nuts, making them more allergenic. In China, on the other hand, most people eat boiled peanuts, and Asians have a much lower rate of peanut allergies.

Other studies show that children who grow up in clean, urban settings are more likely to develop food allergies than their counterparts who are raised in rural areas. One theory that explains this data is called the hygiene hypothesis: our country’s increasing cleanliness has somehow changed the behavior of special antibodies called immunoglobulin E, or IgE. As we have become more sanitary, and the use of antibiotics has reduced the number of infections, IgE have less work to do, making them more likely to attack new things.

Dietary habits may have influence

Eating habits may also explain the increase. Children who are exposed to allergens at an early age develop a greater tolerance for those allergens. As an example, the peanut allergy rate in Israel is very low compared to the U.S., and some people say this is because many Israeli children eat peanut snacks at a younger age and more frequently than American kids.

Another theory goes as follows: foods that tend to be allergenic, such as milk and peanuts, are used more commonly now than in the past. Milk is a source of protein supplement in many prepared foods, for instance, and more people eat shellfish now than in years past.

In Japan, where soy is used in many prepared foods, the number of people with soy allergies has increased. “You could make a case for the fact that we are introducing peanuts, in the form of peanut butter, to people at a very young age, which would affect the prevalence rate for people who are sensitive to that allergen,” says John Anderson, MD, director of the Allergy and Immunology Training Program at Henry Ford Hospital in Detroit in a U.S. Food and Drug Administration (FDA) consumer posting.

Although the answer to why food allergies have increased is still up in the air, the current treatment for anyone who suspects a food allergy is clear cut: Avoid the food in question, and get evaluated by board-certified allergy expert. Although most food allergies only produce mild symptoms, such as hives or a tingling or itching sensation in the mouth or lips, some people do experience life-threatening reactions to foods such as shellfish, peanuts, or tree nuts, so food allergies should not be taken lightly.

Barbara C. Bourassa is a freelance writer and editor living in North Andover, Mass.