Food Allergy Researchers Find Links, But Mysteries Remain

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August 01, 2009 08:00 AM

by Liz Colville

Scientists are uncovering links between food and other allergens, such as pollen and dust, by looking at “regional anomalies” among allergens and the connections between allergen proteins.

Conference, Study on Food Allergies Tackle Mysteries

A recent conference in Vienna, Austria aimed to examine some of the murky issues surrounding food allergies and highlighted findings from an ongoing study looking into regional differences among allergy sufferers in Europe, Australia, India, China and Ghana.

The study, led by an “international task force” called EuroPrevall, is looking at “regional anomalies” in food allergies, New Scientist’s Andrew Watson explains. Its authors chose to delve deeper into this aspect of food allergies, seeking out a possible correlation between “the prevalence of particular allergies and local eating habits and environmental conditions,” which could help uncover “what gives rise to some food allergies in the first place.”

The study also aims to overcome some of the pitfalls of previous studies, many of which have relied on “self-reported” allergies rather than those that had been confirmed with tests.

EuroPrevall has found some promising connections between other types of allergies—pollen and dust mites, for example—and food allergies to shrimp, apples and other foods. This is due to the similarities of proteins found in these disparate allergens. Generally speaking, “many allergens seem to share similarities in their amino acid sequences that might confuse the immune system,” Watson says.

This explains why a person who moves to a certain region might suddenly become allergic to a new food: The person has also come into contact with a new type of pollen containing a similar protein to the food. For example, “some migrants from east Asia to northern Europe suddenly develop an allergic reaction to jackfruit once they have come into contact with birch pollen,” Watson writes.

It appears that the person would start with a pollen allergy because the protein in the pollen “can reach the bloodstream intact”—through the lungs rather than the digestive system—which then activates an allergic reaction, causing the person to “become sensitive to similar looking proteins.”

Recent Developments: Tackling nut allergies with desensitization

A recent British study published in the journal Allergy suggests that slowly introducing an allergen to those who are intolerant may successfully treat the allergy. Four children with life-threatening peanut allergies were given doses of peanut flour for several months. After the study, they were still intolerant to large doses of the allergen, but could tolerate accidentally eating a peanut. Other studies at U.S. universities have had similar findings.

This method is a kind of immunotherapy, the treatment often used to help those intolerant to allergens such as pollen, dust and dander, according to a 2008 report by the National Jewish Medical and Research Center, which worked with other institutions on a peanut desensitization study. But in those cases, sufferers are given shots of allergens to build up a resistance, whereas with food allergies, such shots “can cause severe allergic reactions.”

Related Topic: Food labeling poses challenges

The mislabeling of allergens in a Whole Foods brand chocolate bar in 2007 brought to light the difficult and sometimes inaccurate process by which foods are labeled as safe or unsafe for allergy sufferers. The Chicago Tribune’s Sam Roe says that customers are “at the mercy of a food chain with little accountability … Getting any single product on the shelves of any grocery store may involve a dozen firms and suppliers, each one not entirely certain of the other's health standards.”

But thanks to legislation—“[b]y law, ingredient labels must disclose whether products contain major allergens”—companies are getting better. Even cross-contamination warnings, not required by law, are now being printed by “a soaring number of companies.”

Still, the language of labels can be “confusing,” Roe says, and a Whole Foods spokesperson admitted to him that testing and examination of its products’ allergens and cross-contamination potential was “a continual education.”

Reference: Food allergy definition; Web Guide to Allergies

A food allergy is a reaction by the body’s immune system that occurs soon after eating a food, Mayo Clinic explains. “Even a tiny amount of the allergy-causing food can trigger signs and symptoms such as digestive problems, hives or swollen airways,” and sometimes more severe reactions including anaphylaxis. It is “easy to confuse a food allergy with a much more common reaction known as food intolerance,” Mayo Clinic adds.

FindingDulcinea’s Web Guide to Allergies offers an extensive look at some of the best Web resources for understanding a variety of allergies in children and adults. Find information on different types of allergies and where to find doctors, and read allergy news and research.

“Nuts Over Nut Allergies”

Approximately 3.3 million Americans in the United States have nut allergies, and although the allergies can be quite serious, a Harvard professor says Americans are probably going too far to protect themselves.

According to Time magazine, a school district in Massachusetts recently evacuated a school bus full of children after a peanut was found on the floor. In 2006, a town in Connecticut cut down three large hickory trees (which produced nuts) near the property of a woman who said her grandson had a nut allergy.

Dr. Nicholas Christakis, a physician and social scientist who has a child in the Massachusetts school district, decided to write an article after the school bus episode. Christakis’ article, which was published in the British Medical Journal, questioned whether “so-called precautions” about nut allergies were becoming more of a “societal hysteria.”

Each year, there are 30 million hospitalizations in the United States, according to The New York Times Well Blog, with only 2,000 due to food allergies. Approximately 150 people a year die from food reactions. Meanwhile, 10,000 children a year are hospitalized with brain injuries from sports; 2,000 children drown a year; and 1,300 die in firearms accidents.

“We try to relieve anxiety about nut allergy by signs saying, ‘this is a nut free zone,’ which suggests that nuts are a clear and present danger,” the Well Blog quoted Dr. Christakis as saying. “But in doing so, we increase the anxiety.”

“The issue is not whether nut allergies exist or whether they can occasionally be serious,” professor Christakis said in an article by The Daily Telegraph. “Nor is the issue whether reasonable accommodation should be made for the few children who have documented serious allergies. The issue is what accounts for the extreme responses to nut allergies and what to do about the responses and the allergies themselves.”




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