Sesame seed allergy

As an allergy fellow in training in Shreveport two years ago, I encountered a recent account of a 1-year-old child who had a severe, or anaphylactic, allergic reaction at a local Mediterranean restaurant. This child, who had never had any allergies, developed an immediate rash, vomiting, shortness of breath and wheezing. It was a severe food allergy, and the child had to go to a nearby emergency room and receive an epinephrine shot.

When presented with this food allergy puzzle, I first asked about the “Big 8” food allergies: milk, eggs, peanuts, tree nuts, fish, shellfish, wheat and soybeans. These eight foods account for the overwhelming majority of food allergies in the United States. However, this child had eaten all of these foods without problems.

After ruling out those eight traditional food allergens, the next question I asked was about a common food allergen that is recognized and labeled in Australia, Canada and the European Union but not in the United States: sesame seeds. I reached out to the parents, who then brought the child in so I could test him. As I suspected, sesame seeds were the culprit of his severe allergic reaction!

Sesame seeds (which we see on the top of hamburger buns) can come in many other forms. They are commonly found in veggie burgers and Japanese cuisine. Also, Mediterranean cuisine makes it into a concentrated paste called tahini. This paste is found in hummus and as a flavoring or spice in other foods. The child had eaten at a Mediterranean restaurant the day of his ER visit and, presumably, had eaten tahini or hummus at that restaurant. He received an epinephrine auto-injector (“Epipen”), and I told his family to avoid sesame seeds and sesame products completely.

This year, his life, and millions of others, got easier. Starting Jan. 1, 2023, sesame seed is now considered a major food allergen with the implementation of the Food Allergy Safety, Treatment, Education and Research (FASTER) Act. This was passed and signed into law in 2021. Food manufacturers must now label sesame in plain English just like the other Big 8 food allergens. Before 2023, this was a voluntary requirement for manufacturers.

This law is helpful for the more than one million patients in the United States with sesame allergy, including that child here in Shreveport. This does not impact food already manufactured and sitting in stores or homes before Jan. 1, so it is important to be cautious about reading labels for food from last year.

Seeing these new labels may leave the public wondering: Can I have a sesame allergy without knowing it? Does this mean eating a few sesame seeds on a hamburger bun can trigger an allergic reaction in the sesame seed allergic patient? What kind of reactions do I need to be looking out for?

Food allergy symptoms usually occur within the first few minutes or up to one hour after consumption and can have symptoms such as itching, hives, swelling, diarrhea, wheezing and the potentially life-threatening reaction called anaphylaxis (which is when an immediate rash is followed by either lung, stomach, cardiac or neurological symptoms.)

However, in this specific case of sesame seed allergies, the patient would need about 600 seeds to elicit a reaction. You will be hard-pressed to find many seeds in most foods, but that high concentration can be found in less than half a teaspoon of tahini sauce. So, educating yourself on the types of foods and cuisines to watch out for is important. This is similar to those with a soy allergy. Although many foods contain trace amounts of soy, they often are not enough to trigger an allergic reaction like concentrated soy in soy milk or tofu would. The “triggering dose” may be well below what is typically encountered in the average American diet. It is also difficult to separate the symptoms of food intolerance from a food allergy. Food intolerances are common as well and can include, for example, lactose deficiency, which is an intolerance to milk but not a milk allergy.

Due to these complexities, it is best to have discussions of food allergies with an allergy-immunology specialist. Testing by skin or blood can be safely performed and interpreted by an allergist. If the diagnosis is not clear, an oral food challenge can be performed while being observed in the doctor’s office, and the allergy may be able to be ruled out altogether.

The best way to find a fellowshiptrained allergist is to check the American College of Allergy, Asthma and Immunology’s website at www.acaai.org/find-an-allergist.

Anand Bhat, M.D., is a Fellowship-trained allergist and immunologist treating patients at Highland Clinic.