Wheat is the grain on which Western Civilization was built. It's been used for thousands of years as the foundation of our diet. But 1 out of 100 Americans has a condition called Celiac Disease, which is an intolerance to wheat, barley and rye. Its symptoms can be subtle, but if you don't stick to a gluten-free diet you could be damaging your body and not even know it.

Nothing in the cook family's kitchen contains wheat, rye or barley. Everything is gluten-free.

8-year-old Anna has celiac disease. Her primary symptom was weight loss.

"She had lost somewhere between 10 and 20 pounds."

A blood test and biopsy of her intestine confirmed Anna had damage from the disease.

Dr. Joseph Murray of Mayo Clinic Gastroenterology department says, "The damage that happens is an immune reaction. It's a slow, smoldering inflammation that occurs in the upper part of the small intestine."

Dr. Murray says gluten is a protein found in wheat barley and rye. The inflammatory process it causes damages the finger-like projections called villi that line your upper intestine. This prevents absorption of nutrition. Long-term effects include diarrhea, constipation, weight loss, malnutrition, irritability, osteoporosis, infertility, and even colon cancer.

"The primary treatment is dietary," says Dr. Murray.

Absolutely no gluten. And no cheating.

"Many people with celiac disease seem to be able to get away with eating some gluten and not appear to get ill. They don't get any symptoms. But they will almost certainly be getting damage in their intestines, says Murray.

So people with celiac need to be aware of obvious sources like wheat breads and pasta, but they also need to know about hidden sources. For example, there's gluten in some toothpastes, denture fixatives and lip balm. And you can find lists of gluten free products on the internet, in books and in many grocery stores. Sticking to a gluten- free diet will keep people like Anna healthy.

Dr. Murray says celiac disease is sometime hereditary, so if one family member has it, the rest of the household should be screened too.

And if you do have the condition, a gluten-free diet can help you live a normal, healthy life. Just remember, always check your labels to make sure you are buying gluten-free. If you're not sure, call the manufacturer.

For more information, visit the Mayo Clinic Website.