The Celiac Disease Foundation estimates that one in 100 people have Celiac Disease, which triggers small intestine damage when gluten is consumed.
But some of those patients may be substituting one allergen for another. Manufacturers of gluten-free products sometimes add in lupin, as a flour alternative. The legume could be dangerous, or even deadly to certain people.
Thomas Harper, MD, with Charleston Allergy & Asthma, says people with the most common allergy - to peanuts - need to pay extra attention, because lupin is from the same plant family as the peanut.
"People are just going to have to read labels," he says. "If something says … lupin flour on it, it can be spelled lupine, then if they're peanut allergic, they probably need to stay away from that."
Harper says an allergy can be severe.
"They can have anything from itching, hives, flushing, vomiting, diarrhea," he says. "They can have edema, they can have anaphylaxis – it can go all the way to something life-threatening."
The Food and Drug Administration recently put out a statement on its website, and it currently monitoring complaints.
"With the growth of the gluten-free market, we're going to see more products with lupin in them coming into this country," FDA Senior Medical Advisor Stefano Lucciolo says.
Lupin has been used in European products for years, but it is now becoming more popular stateside. In Europe, lupin is required to be listed as a potential allergen. In America, only the eight most common allergens are required to be listed as such: soy, eggs, milk, wheat, fish, shellfish, tree nuts, and peanuts. All other foods, including lupin, may just be listed under "ingredients."
"What worries me is that we will do it like Europe does and start blending it into regular flours, not just keeping it for a gluten free market," Lucciolo says.
The FDA stresses that lupin is considered a safe and nutritious food for the majority of people, who are not allergic to it.