Is it our imagination, or are gluten intolerance, and dietary disorders in general, increasingly in the news? Does this mean they're on the rise?

The answers are yes and yes, according to experts.

"It is indeed well documented that all autoimmune [and allergic] disorders are on the rise worldwide, but limited to developed areas," said Stefano Guandalini, founder and medical director of the University of Chicago Celiac Disease Center, in an e-mail interview.

"In general, it is safe to say the rates about double every 20 years or so."

There are various theories as to why, but the most prevalent is the "hygiene theory" -- in other words, as a society we're just too clean. As a result, the immune system, largely controlled by the gut, receives inadequate stimulation, Guandalini said.

With autoimmune disorders, which include gluten intolerance and type 1 diabetes (but not allergies), the body attacks itself rather than the invasive substance, causing permanent damage if allowed to continue.

Unfortunately, with all the attention given gluten intolerance -- a plethora of new cookbooks, gluten-free items on restaurant menus, new gluten-free food products -- some people are adopting a gluten-free diet on their own.

This is always a bad idea, said both Guandalini and Carol M. Shilson, executive director of the center and a celiac disease sufferer herself.

"There's no scientific evidence that it's better for you if you don't have celiac disease," Shilson said.

The problem is, even in healthy people, gluten -- a protein found in wheat, rye and barley (and possibly oats) -- is not an easy substance for the body to digest. If you eliminate it from your diet for any amount of time, "it's very hard to go back to a regular diet."

That makes going gluten free a bad idea even for people with symptoms who suspect they are gluten-intolerant.

"Because it is a lifelong genetic disease that can be passed on, it's important to get a proper diagnosis," Shilson said. "And you have to be eating a regular diet [with gluten] or all the diagnostic tests will be rendered invalid."

Healthy people who eliminate gluten also are exposing themselves to "risks of some micronutrient deficiency or of excessive intake of carbohydrates," said Guandalini.

Some further facts:

* Prevalence of gluten intolerance for average, healthy people is 1 in 133; for people with first-degree relatives (parent, child, sibling) who are celiac, 1 in 22; and for those with second-degree relatives (aunt, uncle, cousin) who are celiac, 1 in 39.

* Estimated prevalence for African-, Hispanic- and Asian-Americans is 1 in 236.

* Celiac disease affects at least 3 million Americans.

* Once diagnosed, gluten intolerance is for life, and the only treatment is elimination of gluten from the diet.

* A significant number of people with celiac disease -- 60 percent of children and 41 percent of adults, according to one study -- do not exhibit any symptoms, which include but are not limited to diarrhea or constipation.

* The average length of time it takes for a person with symptoms to be diagnosed with celiac disease in the United States is four years.

* Gluten intolerance is not the same thing as wheat allergy or gluten sensitivity, neither of which is an autoimmune disorder. There is currently no diagnostic test for gluten sensitivity, though researchers, including those at the Celiac Disease Center in Chicago, are working to develop one.