That means that if you suffer from the allergy, peanut butter sandwiches are out. You can't snack on apple slices with Jif. You can't even eat any food that's been processed with peanuts; sometimes, just a tiny amount of the stuff is enough to cause a severe reaction.
But there's hope! Researchers in Britain believe they have determined a possible trigger for the allergy, according to an Oxford University study set to be published this week.
The new study, which will be published Monday in the Journal of Allergy and Clinical Immunology, determined that dry-roasted peanuts were more likely to cause an allergic reaction in mice than their raw counterparts.
Researchers found that dry-roasting the peanuts caused chemical changes, because of the high temperatures that the roasting process requires. Their research suggested that a person's immune system could pick up on those changes, "priming" them for an allergic response, according to a news release.
That might help explain why more people suffer from peanut allergies in Western countries, where dry roasting is more common, than in East Asia, where, the news release noted, "peanuts are more often eaten raw, boiled or fried."
"People with higher allergic background often have genetic dispositions to various types of allergies including to peanuts," Oxford researcher Amin Moghaddam said in an e-mail. "But as [we] and others have argued, dramatic recent rises in peanut allergy and the geographical discrepancies cannot simply be attributed to a genetic background."
Here's how the study worked: Two groups of mice were exposed to either dry-roasted or raw peanuts through a few different methods.
Some mice had purified peanut proteins injected under the skin, others had the proteins applied to skin lesions, and others had it introduced only through gastro-intestinal routes. The researchers later measured the responses the mice had to additional exposure.
"The results of all methods unanimously demonstrated a robust higher allergenicity for dry roasted peanut proteins," Moghaddam wrote in his e-mail to The Post.
What comes next? Figuring out how relevant this finding is to human allergies and trying to clarify how the chemical changes that happen during the roasting process trigger the reactions, Moghaddam said.
We specifically asked about peanut butter, because well … come on, who wouldn't ask about peanut butter?
"Peanut butter is a popular product and is mainly made of dry roasted peanuts," Moghaddam wrote. "We are currently investigating methods that could be food industry friendly and that can be used to eliminate potential harmful chemical changes.
"If the relevance of dry roasting to human allergy is established and the harmful chemicals are confirmed, their prevention or elimination could potentially make such products safer."
Quentin Sattentau of Oxford's Sir William Dunn School of Pathology cautioned in a statement that the research "is at an early stage and we think that it would be premature to avoid roasted peanuts and their products until further work has been carried out to confirm this result."
James R. Baker Jr., the interim chief executive of the national nonprofit Food Allergy Research & Education, said in a statement Sunday that peanut allergy "is an extremely important problem" and that "the results concerning dry roasted peanuts are interesting and provocative, and deserve confirmation in humans."
Patrick Archer, the president of the American Peanut Council, said he hadn't had a chance to read and review the Oxford study and therefore couldn't comment directly on its findings. But, Archer said through a spokeswoman Sunday, the peanut industry trade association "supports any research that sheds light on the underlying causes or a cure that helps individuals with allergies."