News 1 in 5 adults think they have a food allergy. Fewer actually do, study shows January 4, 2019 Sean Rossman, USA TODAY Comments Off on 1 in 5 adults think they have a food allergy. Fewer actually do, study shows A new study shows 1 in 10 adults are allergic to foods like peanuts, shellfish and tree nuts. Although more believe they're allergic.