WASHINGTON (AP) -- Medical scientist Chaitan Khosla had a personal reason to study Celiac sprue -- both his wife and son have the rare, debilitating digestive disorder. Now the Stanford University researcher says he has identified the cause and may have found an enzyme that will control the condition.

Celiac sprue starts with a severe inflammation of the intestine that is caused by eating gluten, an important part of the cereal grains wheat, rye, barley and oats. For Celiac sprue patients, even a tiny bit of cereal grain gluten can cause diarrhea, pain and other problems.

The only treatment is avoiding any form of cereal grains, a diet that is almost impossible to follow because gluten is in hundreds of products, Khosla said.

"If you are diagnosed with Celiac sprue, typically the physician gives you a referral to a dietitian who gives you a book the size of the New York phone book that lists all the things you can't eat," he said. "You can't buy 90 percent of the things in most grocery stores."

Khosla said he started experiments to find the fraction of gluten that prompts the inflammation reaction in Celiac patients.

Laboratory tests isolated a large gluten protein, called a peptide, that Khosla found was not digested in the intestine. For most people, the peptide passes harmlessly out of the body. But not in Celiac sprue patients.

"The peptide is essentially like sand," Khosla said. "If most people ate it, not much would happen. But in the small intestines of Celiacs, this peptide is highly inflammatory."

Khosla said he and his colleagues also have isolated an enzyme from bacteria that is able to break the peptide into pieces, allowing the molecule to pass harmlessly through the gut in test animals.

The researcher said it is hoped the enzyme can be turned into a supplement that Celiac patients could swallow before a meal. The enzyme would tear apart the troublesome gluten molecule and prevent the intestinal inflammation, Khosla said. This would permit them to eat wheat and other grains.

Khosla said the enzyme may work in the same way that people who are lactose intolerant take an enzyme to enable them to digest milk and other dairy products.

Research into the enzyme is at an early stage. Khosla said it may take several years before it is ready for tests on humans.

Celiac sprue is an inherited condition that affects less than 1 percent of white people. Some studies have estimated that about one person in 5,000 in the United States has it, but others say the rate may be as high as one in 200. Some researchers say the disorder may be more common in some European countries.

The disorder can be diagnosed in children, usually after a long siege of diarrhea and a failure to grow and gain weight normally.

Many patients are not diagnosed until their middle years. By then, the constant inflammation from Celiac sprue can cause diarrhea and other disorders. Some types of intestinal cancer, rashes, brittle bones, short stature, dental problems and even infertility have been linked to Celiac sprue, experts say.

Most patients control the condition by avoiding most cereal grains. They are able to eat corn and rice, which have a different type of gluten.

Dr. Z. Myron Falchuk, a gastrointestinal disease expert at Harvard Medical School, said the Khosla study was an important paper that could lead to therapies to relieve Celiac sprue symptoms.

"This shows us the part of the gluten that causes the damage," Falchuk said.

Dr. Joseph A. Murray, a Celiac expert at the Mayo Clinic, said the Khosla study is "a breakthrough." But he said the use of Khosla's enzyme to block the immune response to gluten is "very theoretical" and uncertain.

"In order for an enzyme to work, it would have to break down all of the gluten molecule and do it very quickly, before the immune system detects it in the gut," said Murray. He said it will takes years of work to perfect such an enzyme but said "it does offer a ray of hope."

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