En español | Everywhere you turn — from the corner bakery to the stadium concession stand — you’re increasingly likely to find gluten-free foods. Americans spent $2.6 billion on gluten-free products in 2010, 30 percent more than four years earlier.

Clearly gluten — a protein found in wheat, barley and rye — is today's ingredient non grata.

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Experiment with new grains. Brown rice and quinoa can stand in for some wheat-based foods. — Photo by Getty Images

Is gluten-free just another foodie fad? Or is it a potentially dangerous ingredient?

The answer is complicated. For the estimated 3 million Americans with celiac disease — an auto-immune illness that damages the lining of the digestive tract — exposure to gluten can trigger a host of serious symptoms, including vomiting and severe abdominal pain. For the millions more who test negative for celiac but insist they feel better after eliminating gluten, the scientific evidence is less convincing. Those people may be legitimately gluten-sensitive. Or perhaps they're simply eating a healthier diet, says Mayo Clinic gastroenterologist Joseph Murray, M.D., who notes that junk food tends to have high amounts of gluten. “Sometimes when I see someone who feels better off without gluten, I say, 'That's a very healthy diet. You could probably add some gluten to that and not feel any different.' "

Suspect you're gluten-sensitive? Give up gluten for two weeks, then reintroduce it and see how you react, says Trudy Scott, president of the National Association of Nutrition Professionals. "That's a very powerful way to find out if gluten affects you."  

Also of interest: Snacking tips for diet success.