The first oral food challenge to barley
We examined the factors that influenced the results of all barley-OFCs conducted between August 2012 and November 2020 in patients with a history of wheat allergy. An open OFC to cooked barley (6.2% of protein, based on standards tables of food composition in Japan 2015) was performed according to the Japanese guidelines1for patients with a wheat allergy diagnosed by wheat-OFCs; they completely avoided wheat or ingested some amount of wheat products as OIT at the time of barley-OFC. The patients were instructed to ingest 18.6, 62, 186, 620, and 1,860 mg barley protein of cooked barley with 30-minutes intervals until obvious allergic symptoms were observed. Some patients underwent barley-OFC with a different protocol, where they ingested a total amount of at least 236 mg of barley protein. All patients who had negative barley-OFC results were instructed to consume at least 1,860 mg of barley protein at home to confirm that no allergic symptoms were induced.