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OAS

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Cross-Contact or Cross-Contamination: What’s the Difference?

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I’ll be honest with you: distinguishing between cross-contact and cross-contamination used to throw me off. Many people in the food allergy community (my past-self included) often mistakenly use the terms interchangeably.  

The confusion is so widespread that even food manufacturers and allergists mix up the two. In fairness, cross-contact is a new(ish) term, so some have gotten into the habit of labeling everything involving inadvertent food exposure as cross-contamination. “I’ll be the first to admit that I don’t always use the terms correctly,” says allergist Dr. Jordan Scott. “Many of us were trained to use cross-contamination to refer to allergens inadvertently getting into another food source.”

To help clear up some of the confusion, we’re breaking down the difference between the two terms in this post.

Let’s start with some examples.

Cross-contact: This occurs when a food allergen in one food (let’s say milk protein in cheese) touches another food (let’s say a hamburger), and their proteins mix, transferring the allergen from one food to another. These amounts are often so small that they can’t be seen!

In this example, let’s assume I have a severe milk allergy. If the cheese touches the burger, cross-contact has occurred. Even if the cheese is removed from the burger, trace amounts of the milk allergen likely remain on the burger making it unsafe to eat and posing the risk of an allergic reaction.

It’s important to note that most food proteins (with few exceptions, like heat labile proteins) CANNOT be cooked out of foods, no matter how high the temperature. When our daughter underwent oral immunotherapy for her peanut allergy, we were given the option to bake the peanut flour into muffins for her to consume. We were told that the high oven temperature would not affect the protein structure of the peanut flour.

Cross-contamination: Cross-contamination occurs when a bacteria or virus is unintentionally transferred from one food product to another, making the food unsafe. The key mark of distinction is that cross-contamination generally refers to food contamination, not food allergens.

A couple examples: you cut raw chicken on a cutting board before you put it on the grill. You then cut peppers on that same cutting board. The raw chicken juice touches the peppers, therefore posing a risk for bacteria. Or say you purchase a cantaloupe that unknowingly has listeria. The knife used to dice up the melon is now a vehicle for cross-contamination. Unlike cross-contact, properly cooking contaminated foods generally CAN eliminate the food-borne offender.

Is it all making sense now? In short, when referring to food allergens, use cross-contact, and when referring to food-borne bacteria or viruses, use cross-contamination. Easy peasy.

We hope our explanation cleared up any confusion. Now that you’re a cross-contact pro, here’s a guide with tips on how to avoid cross-contact.

Want to discuss this topic further? Still confused? Feel free to reach out to me at mnohe@allergyamulet.com. I’m always game for a good food allergy chat!  :)

-       Meg and the Allergy Amulet Team

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OAS—A Seasonal Mess?

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                         Photo copyright©    National Jewish Health   . All rights reserved. Used by permission.

                      Photo copyright© National Jewish Health. All rights reserved. Used by permission.

Ahh, summer. The season of pool parties, barbecues, gardening, and outdoor adventure. For many though, summer also means seasonal allergies. That’s right, runny noses, itchy eyes, and nasal congestion. But how about an itchy mouth?

If you’ve ever bitten into a raw apple, banana, or piece of celery and experienced an itchy mouth, you’re not alone. This reaction occurs because the proteins found in some raw fruits and vegetables are very similar to those found in plant pollen. Your body perceives these similarly structured proteins as pollen allergens – this recognition overlap is also referred to as cross-reactivity. If you’ve experienced this reaction before, you may have oral allergy syndrome (OAS). Or what Allergy Amulet allergist advisor Dr. John Lee calls: The most common allergy you don’t know you have.

So now you’re probably wondering if you’ve ever experienced OAS, right? The most common symptoms include: itchiness or swelling of the mouth, lips, face, tongue, and throat. These symptoms typically appear right after eating raw fruits or vegetables. OAS is considered a mild form of food allergy, and only in very rare instances has OAS resulted in more serious allergic reactions like anaphylaxis.

Now that we’ve defined OAS, let’s take a closer look at which common plant pollens most often cross react with which fruits and vegetables: 

It’s important to note that OAS isn’t limited to the above chart of fruits and vegetables—certain spices, legumes (peanuts and soybeans), and nuts (almonds and hazelnuts), can also bring about OAS symptoms as well.

The good news? Many people affected by OAS can eat the same fruits or vegetables when they are cooked. Heat alters the protein structure in the food so that the immune system no longer recognizes them as similar to pollen proteins. Peeling these fruits and vegetables before eating them can also stave off an OAS reaction, as these proteins are often concentrated in the skin. However, many allergists recommend avoiding the food in raw form altogether if it’s causing symptoms. Alternatively, consider eating canned versions of these nutritious favorites if you can’t resist them, as processing helps destroy the proteins typically involved in OAS.

If you've experienced OAS symptoms after eating a raw fruit or vegetable, it’s wise to talk to your health care provider or allergist. Because standard food allergen tests (skin prick or blood test) often come back negative for people with OAS, a diagnosis is often made when these traditional tests are coupled with a history of OAS symptoms. Some allergists perform what’s referred to as a “fresh prick by prick” test. This entails pricking the raw fruit or vegetable with a skin prick testing device and then pricking the skin of the patient. This test is generally more accurate because the proteins in raw fruits and vegetables are often not as processed as allergy extracts, which are commonly used in traditional skin prick tests.  

Fascinating.

If you have any questions about OAS, let us know! We’re always up for a good allergy chat.

- Meg and the Allergy Amulet Team

 

Allergy Amulet advisors Dr. Jordan Scott and Dr. John Lee have reviewed this piece for accuracy. 

Dr. Scott is an allergist/immunologist and operates several private allergy clinics throughout the Boston area. He is on the board of overseers at Boston Children’s Hospital, and the past president of the Massachusetts Allergy and Asthma Society. Dr. Scott is an allergy/immunology instructor at the University of Massachusetts.

Dr. Lee is the clinical director of the food allergy program at Boston Children’s Hospital and an Instructor in Medicine at Harvard Medical School. He is also the co-creator of AllergyHome.org, a website that offers online resources to help educate and promote awareness about food allergies in schools, camps, and other settings. Dr. Lee is widely recognized for his work in the food allergy space, and his commitment to patient health.

 

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