Sara Plumby went for months, not knowing why she was in pain.
"I experienced a burning tongue, my muscles would twitch, I had sleep disruptions, and I would wake up in the morning feeling like I wasn't rested," says Sara.
She also had a rash that wouldn't go away.
Sara had recently switched to a nearly all vegetarian diet.
Allergist Matthew Zirwas of the Ohio State University Wexner Medical Center says many of the foods she was eating, like oatmeal, beans and whole grains are high in nickel.
"The reason, we think, is that there's been a shift in dietary habits. As people are trying to eat healthier, they're actually eating more nickel," says Dr. Zirwas.
Unlike other food allergies, nickel doesn't cause a fast reaction.
"It's not like a normal allergy to, say, peanuts. Where, if you look and say a kid is allergic to peanuts. If he eats a peanut, 30 seconds later, his whole body is swelling up, he's having a severe reaction," says Dr Zirwas. "With this kind of allergy, it's much more the cumulative effect of the nickel we eat."
But the most common sign is an itchy, painful rash on the outside of the elbow or the palms.
Dr. Zirwas says, "If you start eating more nickel, it slowly builds up in your body until your immune system gets stimulated enough that you start to break out in this rash."
Nickel is in many other foods, like soy and dark chocolate.
And it can be released from stainless steel pots & pans when you cook acidic foods, such as tomatoes.
If you have an unexplained rash, you might want to keep a journal of what you eat, and ask your doctor about nickel.
"These people will go on for years and years with these itchy rashes over big parts of their body," says Dr. Zirwas.
About 15% of Americans have skin that's sensitive to nickel in jewelry, watches, and clothing. Dr. Zirwas says no one knows how widespread nickel food sensitivities are.
As long as you keep eating those foods, the symptoms won't go away and can get worse.