Making cashews safer for those with allergies


The researchers are presenting their work at the 248th National Meeting & Exposition of the American Chemical Society (ACS) in San Fransisco.

"The only widely accepted practice for preventing an allergic reaction to nuts is strict avoidance -- stay away from the food," notes Chris Mattison, Ph.D. "Clinical trials to test immunotherapy are underway, but we're approaching it from an agricultural perspective rather than medical. Can we change the food, instead of treating the person, so we can eliminate or reduce severe reactions?"

For those with food allergies, responses to offending products can range from mild itching in the mouth or skin to life-threatening anaphylaxis, which makes it hard to breathe. Once every three minutes, someone in the U.S. ends up in the emergency room due to a food allergy reaction -- that adds up to about 200,000 visits a year.

To try to reduce those numbers, Mattison's team is looking at ways to modify proteins in tree nuts and peanuts (which are legumes) that trigger an immune response in people who are allergic. The response is launched by antibodies called immunoglobulin E (IgE), which recognize and latch onto the proteins. Mattison explains that changing the shape of the proteins makes it harder for IgE to find them.

But past research taking this approach has involved harsh chemicals. Mattison, a researcher with the Agricultural Research Service branch of the U.S. Department of Agriculture, wanted to see if his team could achieve the same results, but using compounds that are "generally regarded as safe," or GRAS. These are substances that are accepted by the Food and Drug Administration for use in food and pharmaceuticals.

"We found that the GRAS compound sodium sulfite can effectively disrupt the structure of a couple of the cashew allergens," Mattison says. "And we've done a couple of different tests to show we reduced IgE binding to the proteins when they've been treated with sodium sulfite."

Next, they plan to conduct experiments on whole nuts and test the modified proteins on cells in the lab to see how they respond. They're also looking at enzymes, which are molecules that can cut up proteins, as candidates to disrupt the allergens.

And, although this particular report focuses on cashew proteins, Mattison says the work could have broader implications. The kinds of allergenic proteins the GRAS compound and enzymes affect are not exclusive to one kind of nut.

"One of our goals is to apply our knowledge from the cashew experiments to other tree nuts and to peanuts," he says.