THURSDAY, July 12, 2001 (HealthDayNews) -- New research may explain why the Chinese have much lower rates of peanut allergies than Americans although they eat almost as many goobers: The key could be in how they're cooked.
Americans, it seems, prefer their nuts dry-roasted, which preserves peanut protein, while the boiling and frying methods enjoyed by the Chinese and other Asian societies leave much less of the highly allergenic substance intact.
Americans eat about 2.4 billion pounds of peanuts each year, almost half of that as peanut butter. That works out to about six pounds a person, compared with a figure of between five and six pounds a person in China.
Yet American children are much more allergic to peanuts than their Chinese counterparts. Although roughly one in three U.S. children with food allergies are sensitive to peanut protein, a 1997 study found that Chinese children occasionally have trouble with crab, shrimp, fish, and seaweed, but rarely with peanuts.
The latest study, which appears in the June issue of the Journal of Allergy and Clinical Immunology, was led by Dr. Kirsten Beyer of the Mount Sinai School of Medicine in New York City.
Beyer and her colleagues tested protein levels in two common strains of peanuts, Runner and Valencia, after they'd been roasted, boiled or fried in vegetable oil.
Dry-roasted nuts had more Ara h 1, the principal allergen in peanuts, than either boiled or fried peanuts. Protein in roasted nuts, including Ara h 1 and its companion molecules Ara h 2 and 3, also had much more IgE-binding intensity in blood samples from allergic subjects, which is a measure of its ability to trigger an allergy attack. The immune molecule is present on the surface of so-called mast cells, and when they meet Ara h 1 or another peanut allergen they signal the body to produce histamine and other chemicals involved in allergic reactions.
"You see much more IgE binding to the roasted peanut protein compared to the boiled or the fried," says Dr. Hugh Sampson, director of the Jaffe Food Allergy Institute at New York's Mount Sinai School of Medicine and a co-author of the study.
Boiling exposes peanuts, and therefore their proteins, to a temperature of 212 degrees Fahrenheit, and frying exposes them to 248 degrees. Dry-roasting takes place at 338 degrees, hot enough to potentially create a highly stable form of allergen, the researchers say.
"What we think happens is that this reaction goes on where you get interactions between the sugars [in the peanut] and the protein, and that alters the protein's structure" in a way that makes it more allergenic, Sampson says.
The researchers didn't expose people to heated protein, so they don't know if the various cooking methods truly make a difference in allergic response. "What we don't know is, if people were just fed boiled peanuts would they develop less allergy? But that's our hypothesis," Sampson says.
What To Do
Once you're allergic to peanuts, it won't matter to you how they're prepared, Sampson says. But it may be that people exposed to less allergenic servings are less likely to suffer reactions in the future.
However, people with established peanut allergy shouldn't interpret the findings as license to experiment with different methods of cooking the food, says Dr. Peter Vadas, director of allergy and clinical immunology at St. Michael's Hospital in Toronto. "Absolutely not. It would be foolhardy to try to experiment under those circumstances."
In addition to the cooking method, Vadas says genetics probably also has a hand in why the East has fewer problems with peanuts than the West.
To learn more about peanut allergies, check out the Ontario Medical Association. You can also visit the Food Allergy & Anaphylaxis Network.
