Reality Check: Are Cooked Carrots an OAS Allergy Trigger?

in Food Allergy, Fruit & Vegetable
Published: October 29, 2020
A slices of carrot, cross section,
Photo: Getty

Raw carrots can trigger an itchy mouth, swollen lips and a scratchy throat in people with a condition known as oral allergy syndrome (OAS). Yet many people with a carrot allergy are able to eat cooked carrots. This is because with OAS allergies to vegetables and fruits heat breaks down the proteins that set off the allergic reaction. 

But European research indicates that even cooked carrots may be more allergenic than previously known. The findings show that as cooked carrots cool, the structure of the protein reverts to its raw state – and the potential for an allergic reaction may return.

“The results of our research clearly suggest that sufferers who are sensitive to the carrot allergen should generally avoid eating carrots. Heating carrots does not destroy or only incompletely destroys the protein structures that can cause allergic reactions,” says Dr. Birgitta Wöhrl a biomchemistry professor at the University of Bayreuth in Germany. 

However, Dr. Anna Nowak-Wegrzyn throws some cold water on that conclusion. Don’t toss your carrots just yet, says Nowak-Wegrzyn, who directs the Pediatric Allergy Program at NYU Langone Health in New York and has researched OAS, also known as pollen food allergy syndrome.  

This syndrome, which is related to pollen allergies, usually causes a mild reaction limited to the mouth and throat, as opposed to an anaphylactic reaction. The majority of OAS patients who get an itchy mouth when eating OAS allergy triggers, such as carrots (or other fruits and vegetables), can safely eat those same foods when they are cooked. 

Expert: Cooked Carrots Usually Fine for OAS

“It’s not true that patients with carrot allergies should avoid carrots. You can’t really make recommendations based on a laboratory study that has no patients in it,” Nowak-Wegrzyn told Allergic Living. “If you can tolerate carrots in cooked or baked form, you can continue eating it.”  

Occasionally, if eating carrots is also associated with stomach pain or diarrhea, patients may decide to avoid carrots altogether, she says. But only in rare cases does an OAS carrot allergy cause a severe, full-body allergic reaction.

The main carrot allergen is the protein Dau c1. In the study published in the journal Molecular Nutrition & Food Research, researchers subjected the protein to temperatures of 95 degrees Celsius (203 degrees F). The structure of the protein changed, as expected. But when the carrots cooled to roughly room temperature (77 degrees F), researchers found the carrot protein was largely still intact. 

While the findings may be interesting to scientists, Nowak-Wegrzyn cautions they could lead to unnecessary avoidance of carrots in those with OAS. “Ninety-nine percent of my patients who say their mouth itches when eating raw carrots are fine eating cooked carrots,” she says.  

Related Reading:
All About Oral Allergy Syndrome
Can Fruit & Vegetable Allergies be Related to a Pollen Allergy?
Oral Allergy Syndrome: Why do Pollens and Foods Cross-React?