CHICAGO — A study published Jan. 4 in JAMA Network Open estimated 10.8% of U.S. adults, or more than 26 million, have food allergies. Researchers from Ann & Robert H. Lurie Children’s Hospital of Chicago and Northwestern University also found 19% of U.S. adults think they are food allergic although their reported symptoms are inconsistent with a true food allergy.

“While we found that 1 in 10 adults have food allergy, nearly twice as many adults think that they are allergic to foods, while their symptoms may suggest food intolerance or other food-related conditions,” said lead author Ruchi Gupta, M.D., from Lurie Children’s Hospital and a professor of pediatrics at Northwestern University Feinberg School of Medicine in Chicago. “It is important to see a physician for appropriate testing and diagnosis before completely eliminating foods from the diet. If food allergy is confirmed, understanding the management is also critical, including recognizing symptoms of anaphylaxis and how and when to use epinephrine.”

The study involved 40,443 people age 18 and over who took surveys either online or over the phone. More women (13.8%) had food allergies than men (7.5%). The most prevalent food allergies were shellfish, affecting 7.2 million adults; milk, affecting 4.7 million; peanuts, affecting 4.5 million; tree nuts, affecting 3 million; fin fish, affecting 2.2 million; eggs, affecting 2 million; wheat, affecting 2 million; soy, affecting 1.5 million; and sesame, affecting 500,000.

The Food and Drug Administration requires that all these foods, except for sesame, be disclosed as an allergen on food packaging. The F.D.A. is accepting comments on the prevalence and severity of sesame allergies in the United States and may take action that would require sesame to be labeled.

The study in JAMA Open Network found nearly half of food-allergic adults developed at least one of their food allergies as an adult.

“We were surprised to find that adult-onset food allergies were so common,” Dr. Gupta said. “More research is needed to understand why this is occurring and how we might prevent it.”

Funding for the study came from the National Institute of Allergy and Infectious Disease, the Sean N. Parker Center for Allergy and Asthma Research at Stanford University, Aimmune Therapeutics, and Denise and Dave Bunning. The published study may be found here.