The number of Utahns who can't tolerate gluten is about the same as in northern Europe, where even McDonald's has a gluten-free menu. But the digestive disease is largely undiagnosed and the misery and complications little understood here, according to experts.

Barb Shelley is an accidental expert in gluten intolerance and celiac disease (also called gluten enteropathy or celiac sprue), a disorder that damages the small intestine and interferes with nutrient absorption. She went from doctor to doctor with some of the symptoms, which can include stomach aches, gas, bloating, weight loss or weight gain, migraines, various aches and pains, dental enamel defects, skin rash and premature osteoporosis.

Chronic fatigue is common; in rare cases, cancer — intestinal lymphoma — results. Sometimes there are no symptoms, although the unseen damage continues. It can lead to insulin-dependent diabetes, lupus, osteoporosis, stomach cancer and other serious diseases. And sometimes it's misdiagnosed as irritable bowel syndrome or Crohn's disease.

Shelley had osteoporosis, despite calcium supplements and weight-bearing exercises. A fairly new blood test called a Celiac Panel got to the root of the problem: She can't tolerate gluten, found in wheat, rye, barley and in processed foods including pastas and gravies, cereals and soups. Oats can be cross-contaminated with gluten, as well.

About one in 133 people of all ages reportedly have celiac disease, although most are never diagnosed here. In first-degree relatives of celiacs, the number is 1 in 22. American medical researchers call celiac disease the most widely underdiagnosed illness in the United States and the Gluten Intolerance Group in Utah estimates that 90 percent of Utahns with the disease don't know it. Celiacs often develop other food sensitivities, like lactose intolerance.

Not all reaction to gluten leads to celiac disease, Shelley said. Some people, for instance, with autism or attention deficit disorders have been told by their physicians to avoid gluten and have seen improvements in behavior. But they didn't have the intestinal damage of celiac disease.

When someone with gluten intolerance and celiac disease eats foods containing gluten, the immune system springs into action, damaging the small intestine. The villi, the bitty finger-like protrusions that allow nutrients to be absorbed into the bloodstream, are damaged or even destroyed, according to the National Institutes of Health.

It runs in families and can be triggered by surgery, pregnancy, childbirth, viral infection or severe emotional distress, the NIH says.

The only treatment is a diet that avoids gluten completely, which is not a simple thing, according to Dr. John Zone, chairman of dermatology at the University of Utah, who has become an expert on gluten intolerance because he treats its effects on the skin, a rash called dermatitis herpetiformis or eczema, among others. "It's not as simple as avoiding cake or bread, he says. "Gluten is an ingredient in a large number of commercially prepared foods.