Food allergies - EFR 6-21

Food allergies are one of the most misunderstood health problems related to foods. The following report provides a nice summary of some of the major misconceptions that we need to help the public understand about this relatively infrequent but potentially dangerous problem.

Excerpted from FOOD CHEMICAL NEWS February 19, 1996, pages 6-8

Speaking at a symposium on food allergies held by the District of Columbia chapter of the Institute of Food Technologists, Roy Fuchs, director of regulatory affairs for the Monsanto Company, noted that genetically engineered foods could be used to reduce the potential of food allergies. This remark is in contrast to a concern expressed by some scientists and consumer groups that biotechnology techniques which alter genes may cause unexpected food allergies. Fuchs described the results from a Japanese firm that has reduced the allergenicity of a type of rice by 80%.

True food allergies are actually rare and are often outgrown as children reach maturity, experts noted. But, Dr. Robert Woods, a pediatric allergist at Johns Hopkins University Medical Center explained that, "Kids are uniquely susceptible (to food allergies) because the mucosa of their gastrointestinal tract is much 'leakier,'" or less developed. A true food allergy is one that causes an immunological response in a patient, such as the release of histamine. In the United States, about 5%-6% of infants and 1%-2% of adults are thought to have food allergies, Woods said.

Though rare, the effects of a true food allergy can be deadly. Woods described one case where a nine-year-old boy who breathed in dust from peanuts being eaten by other passengers on an airplane was dead within an hour and a half.

Allergies to milk and soy are often outgrown, but allergies to peanuts, tree nuts, fish and shellfish are rarely outgrown and are the most common allergens for adults, according to Woods.

Avoidance of the offending substance is the most important way to prevent food allergies. This means careful reading of food labels and awareness of uncommon food names (sodium caseinate in milk, for example), Dr. Woods said.

Food manufacturers and processors are taking steps to make sure that high-risk foods such as nuts are not able to contaminate other foods during the mixing and packaging of foods. They are also sensitive to food allergies as a worker safety issue according to Dr. Allen Mathys, vice president of regulatory affairs for the National Food Processors Association.

Consumers also need to understand the degree of sensitivity to an allergen that a person might have. Mathys gave examples of picking offending nuts out of cookies and offering the cookies to allergic individuals, because a person did not understand that enough of the allergen is left to cause a reaction, or people who have even had severe reactions after inhalation of cooking vapors or kissing someone who has recently eaten an allergen.

Mathys advised companies that if a food might contain even a very small amount of an allergen, due to contamination concerns, to include it on the label. "Recalls are costly for companies and dangerous for consumers," he noted.

According to Dennis Hinton of the Food and Drug Administration (FDA), studies being done at FDA suggest the following properties tend to be found in food allergens: heat stability, acid stability, and a protein structure able to bind to certain types of T-cells.

As with many health problems, genetics (our parents, grandparents and so on), plays a role in food allergy susceptibility. "Some people seem virtually incapable of (food allergies), while others are extremely capable," Woods said. People without a family history of allergy have less than a 10% chance of developing one, while those with one family member with a food allergy have a 40% chance. A child with two family members having the same allergy will have an 80% chance of developing that same allergy.

An important thing to remember is that food allergens are ALMOST ALWAYS PROTEINS. That is the reason that using biotechnology to move proteins between foods is a concern. According to Hinton, an allergy researcher, in a very few cases, smaller chemicals, such as sulfites and MSG, may bind with proteins that then become the source of a food allergy.

Some clues to pinpointing a food as an allergen are:

* the timing of the reaction - food allergies almost always show symptoms within an hour of exposure

* the types of symptoms (hives, swelling, gastroenterological distress are among the most common)

* the reproducibility of the reaction - a food will always cause an allergy, particularly in adults, not just sometimes

Many more people think that they have food allergies than actually do have them, according to Woods. True food allergies are proven in only about a third of the cases. There are other problems related to eating food, such as lactose intolerance, but they are not true food allergies since they do not cause an immunological response in the person, Woods explained.

Skin tests are an initial step in verifying a food allergy. While false positives (the test suggests an allergy even though no allergy is present) are common, false negatives (the test does not suggest an allergy but there really is an allergy) are not common according to Woods. While double-blind, placebo-controlled studies are good, because neither the doctor or the patient knows whether they are getting the food allergen, these studies have the disadvantage of exposing an allergic individual and must be done with extreme caution, Woods explained.