Celiac disease is a condition that damages the lining of the small intestine and prevents it from absorbing parts of food that are important for staying healthy. The damage is due to a reaction to eating gluten, which is found in wheat, barley, rye, and possibly oats.

The exact cause of celiac disease is unknown. The lining of the intestines contains areas called villi, which help absorb nutrients. When people with celiac disease eat foods or use products that contain gluten, their immune system reacts by damaging these villi.

This damage affects the ability to absorb nutrients properly. A person becomes malnourished, no matter how much food he or she eats.

The disease can develop at any point in life, from infancy to late adulthood.

People who have a family member with celiac disease are at greater risk for developing the disease. The disorder is most common in Caucasians and persons of European ancestry. Women are affected more often than men.

People with celiac disease are more likely to have:

• Autoimmune disorders such as rheumatoid arthritis, systemic lupus erythematosus, and Sjogren syndrome
• Addison's disease
• Down syndrome
• Intestinal cancer
• Intestinal lymphoma
• Lactose intolerance
• Thyroid disease
• Type 1 diabetes