In the United States, the top allergens are required to appear on labels when they're among a product's ingredients. Milk, eggs, fish, shellfish, tree nuts, peanuts, wheat and soybeans are all on the list.
A new study says 1.5 million children and adults in the United States may have a sesame allergy. That's a greater number than previously estimated, and makes it the ninth most common allergy. But sesame isn't required to be listed on food labels.
In October, the US Food and Drug Administration requested more information from researchers, medical providers and consumers on the prevalence and severity of sesame allergies to help guide regulation on labeling. The FDA told CNN that it's still reviewing public comments and has not released new information on sesame regulation.
"We see sesame allergies clinically and how difficult it is for families with sesame allergies to avoid sesame, so this seemed like the perfect opportunity to really dig deeper into understanding sesame allergy in the US," said Dr. Ruchi Gupta, co-author of the new study and professor of pediatrics and medicine at Northwestern University.
For the study, published Friday in the journal JAMA Network Open, researchers sent food allergy questionnaires to more than 51,000 households in all 50 states and surveyed 78,800 people.
Researchers estimate about .49% of the US population reports having a sesame allergy and .23% had what's called a "convincing," or true food allergy, with skin, lung, heart or gastrointestinal symptoms. These symptoms included hives, wheezing, heart palpitations, dizziness and belly pain, among others. Others may have been diagnosed with an allergy, but hadn't experienced symptoms.
The .21% of children and .24% of adults estimated to be allergic to sesame in the United States is an increase from the number reported in an earlier, smaller study, which showed a prevalence of .1%.
Sesame on food labels
Sesame is an ingredient found in a variety of spices, sauces and flavorings. And even if food doesn't have sesame, it could still be cooked in sesame oil.
"It's a tricky allergen to control in the kitchen," said Christopher Warren, lead author and epidemiologist at the Center for Food Allergy and Asthma Research at Northwestern University. For example, "in Japanese spices & seasonings, it's almost always present."
On Tuesday, Illinois Gov. J.B. Pritzker signed into law a measure that requires packaged food in the state to have sesame labeled if it's an ingredient. The policy aligns with those in Australia, Europe, New Zealand and Canada, which all have sesame labeling requirements.
In Canada, sesame labeling has been required since 2012.
"It's important to be aware that we can get accidental exposure and labeling is one of the ways to inform consumers that an allergen may be present," said Dr. Moshe Ben-Shoshan, an associate professor of pediatrics at Montreal Children's Hospital in Canada.
Whether food labeling in Canada has reduced the number of accidental exposures hasn't been proven with studies.
"If something makes sense we don't need to prove it sometimes," Ben-Shoshan said. "I think it should also be in the US. It's a simple measure to install and it could protect lives."
The number of people in the United States who had sesame allergies from unlabeled food products wasn't calculated in the new study, according to Warren. Another limitation of the study was that people self-reported allergies and symptoms, without medical tests to confirm their results.
But even so, the study provides evidence of the "increasing burden of sesame allergy" in the United States, according to Jennifer Protudjer and Dr. Elissa Abrams from the University of Manitoba in Canada, who wrote an editorial alongside the study.
The study "supports an increasing need for diligence and awareness of the role of sesame allergy in the United States," they wrote. "It also suggests that sesame allergy may be a persistent allergy, affecting children and adults, and may result in severe reactions as well."