ATLANTA -- It sounds like an unfolding epidemic: A decade ago, virtually no one in the United States seemed to have a problem eating gluten in bread and other foods. Now, millions do.
Gluten-free products are flying off grocery shelves, and restaurants are boasting of meals with no gluten. Celebrities on TV talk shows chat about the digestive discomfort they blame on the wheat protein they now shun. Some churches even offer gluten-free Communion wafers.
"I don't know whether there's more people getting this or that more people are noticing" they have a problem, said the Rev. Richard Allen, pastor at Mamaroneck United Methodist Church, north of New York City.
Or is it just another food fad?
Faddishness is a big part of it. Americans will spend an estimated $7 billion this year on foods labeled gluten-free, according to the market research firm Mintel. But the best estimates are that more than half the consumers buying these products -- perhaps way more than half -- don't have any clear-cut reaction to gluten.
They buy gluten-free because they think it will help them lose weight, or because they seem to feel better, or because they mistakenly believe they are sensitive to gluten.
"We have a lot of self-diagnosing going on out there," said Melissa Abbott, who tracks the gluten-free market for the Hartman Group, a Seattle-area market research organization.
Fads aside, research suggests more people are truly getting sick from the gluten found in wheat, rye, and barley, but the reasons aren't clear.
In the most serious cases, gluten triggers celiac disease. The condition causes abdominal pain, bloating, and intermittent diarrhea. Those with the ailment don't absorb nutrients well and can suffer weight loss, fatigue, rashes, and other problems.
A research team led by the Mayo Clinic's Dr. Joseph Murray recently looked at blood samples taken from Americans in the 1950s and compared them with samples taken from people today. He determined that celiac disease was increasing. The research confirms estimates that about 1 percent of U.S. adults have it today, making it four times more common now than it was 50 years ago, Dr. Murray and his colleagues reported Tuesday in the American Journal of Gastroenterology.
That translates to nearly 2 million Americans with celiac disease.
Celiac disease is different from an allergy to wheat, which affects a much smaller number of people, mostly children who outgrow it.
Scientists suggest that there may be more celiac disease today because people eat more processed wheat products such as pastas and baked goods than in decades past, and those items use types of wheat that have a higher gluten content. Gluten helps dough rise and gives baked goods structure and texture.
Or it could because of changes made to wheat, Dr. Murray said. In the 1950s, scientists began cross-breeding wheat to make hardier, shorter, and better-growing plants. It was the basis of the Green Revolution that boosted wheat harvests worldwide.
But the gluten in wheat may have somehow become even more troublesome for many people, Dr. Murray said.
At one of Atlanta's largest and busiest health-food stores, Return to Eden, manager Troy DeGroff said more than a third of his customers come in for gluten-free products for themselves or their family.
"Thank you, Elisabeth Hasselbeck," he said, referring to one of the hosts of the daytime talk show The View who helped popularize gluten-free eating.
It's hard to say how many of his customers have a medical reason for skipping gluten. But "they're at least paying attention to what they're sticking in their mouth," he said.