At least one million children and adults in the United States are allergic to sesame, an ingredient used in everything from hummus to snack bars, researchers reported on Friday.
The finding indicates that sesame allergy is more prevalent than previously known, although still far less common than peanut allergy. But sesame is not among the allergens that the Food and Drug Administration requires manufacturers to list on food labels.
“Sesame allergy is becoming a common allergy in the U.S.,” said Dr. Ruchi S. Gupta, a professor of pediatrics at Northwestern Medicine in Chicago and senior author of the study, which was published in the journal JAMA Network Open. “The impact on over a million people in the U.S. is significant.”
The study relied on online and phone survey responses from 40,453 adults and 38,408 children. People who have had at least one symptom of sesame allergy made up an estimated 0.23 percent of the population, Dr. Gupta and her colleagues found.
Those who have been diagnosed with the allergy but have never experienced a symptom accounted for an estimated 0.11 percent of the population.
“That’s about 1.1 million people in the U.S. who currently probably have a sesame allergy and therefore are avoiding sesame in their daily lives,” said Christopher M. Warren, an epidemiologist at the Northwestern Center for Food Allergy and Asthma Research and lead author of the study.
Exposure to a food allergen like sesame can lead to an anaphylactic reaction, including throat swelling and a drop in blood pressure. Severe reactions can be fatal.
Among people with a sesame allergy, 62 percent said they had a prescription for epinephrine, the injected medicine used to ease an allergic reaction. Of those with an epinephrine prescription, about one third said they had used the medication at some point.
Many people in the survey reported symptoms of sesame allergy but were never actually diagnosed, Dr. Gupta noted.
“If you eat a food and have a reaction, it is important to get it diagnosed, because you want to make sure it really is an allergy to that food before you spend your life avoiding that food,” she said.
Currently, the federal government requires manufacturers to tell consumers when a product was made using any of eight allergens: milk, eggs, fish, shellfish, peanuts, wheat, soybeans and tree nuts. Consumers can find those allergens printed in the ingredients list or in a special warning.
But sesame, which Dr. Gupta referred to as “the ninth most common allergen,” wasn’t part of the 2004 law that mandated the labeling. Consumers cannot know for certain whether food at the grocery store has sesame in it. Even if sesame were used as an ingredient, it might be described as “natural flavors” or “spices.”
Lisa G. Gable, chief executive of Food Allergy Research & Education, a nonprofit organization in McLean, Va., hopes that this latest study convinces the F.D.A. to make a change.
“It elevates, with great specificity, the data related to the impact of sesame on the lives of individuals who have to basically avoid that food,” Ms. Gable said.
The F.D.A. is considering adding sesame — which is already regulated in the European Union, Canada and Australia — to the list. In 2018, the agency issued a request for information to “learn more about the prevalence and severity of sesame allergies in the U.S.”
“The F.D.A. has received more than 4,800 comments from consumers, industry associations, medical professionals and academics,” a press officer for the F.D.A. said in a statement. “We are carefully considering all of the comments received as we explore different options for possible agency actions and will provide updates as they become available.”
Certain food allergies already covered under the labeling law appear to be less common than sesame allergies. Allergies to macadamia nuts, a type of tree nut, were only found in 0.008 percent of children and adults in the U.S., according to the study.