A decade ago, most Americans had never heard the word gluten. Now millions are trying to cut it out of their diets.
Gluten gets blamed for everything from stomach pain to fatigue, and many people are under the impression their diets would be healthier without it.
But what does gluten really do to the body, and what's behind the recent backlash against this natural component in foods we've been eating for centuries?
Gluten is a protein found in wheat. It causes serious problems for people who have celiac disease -- about one percent of the population. For them, gluten stimulates an immune system response that attacks and damages the intestines.
Others may have milder symptoms of gluten sensitivity. And for some, the health benefits are harder to explain.
Dr. Steven Lamm of NYU Langone Medical Center says people may be more sensitive to gluten these days because there's simply more of it in our food. "It appears that the wheat products from thousands of years ago probably have less gluten than they do now," he explained.
Misty Nelson, a New Jersey mother of two, is one of those who says giving up gluten has helped her feel better. She used to have serious stomach pain until she stopped eating wheat products seven months ago. She told CBS News' Marlie Hall it made a difference right away - she felt "Fabulous. Immediately."
At a store called G-Free in New York City, everything they sell is gluten free. Owner Lynn Shuter says her customers believe gluten is linked to a range of health issues: "Everything from being really tired all the time, acne, infertility, IBS [inflammatory bowel syndrome]."
Proven or not, those concerns are helping to drive a booming market in gluten-free foods. Americans are expected to spend more than $15 billion a year on gluten-free foods by 2016. Gluten-free foods can cost several times more than their regular equivalents, and more products are being introduced all the time.
A March 2013 survey by market research firm the NPD Group found that 29 percent of Americans were cutting back or avoiding gluten entirely.
Is it a diet fad, or a reflection of legitimate health concerns? "I believe it's a little bit of both," Lamm told CBS News.
He says more research is needed to understand how gluten affects the body. Some researchers are looking into whether the culprit is not gluten at all, but a type of carbohydrates called FODMAPs which are found in wheat as well as many fruits, vegetables and other products.
Whatever the explanation, Nelson has no doubt that giving up gluten was the right thing for her. "No doubt at all," she said. "And you know what, I'll never go back."