According to the National Institutes of Health, an estimated 3 million Americans suffer from some form of celiac disease, which is the inability to digest glutens found primarily in wheat. With many Americans consuming a wheat flour-based diet, celiac disease is on the rise—yet most people don't even know they have the condition. Dr. Oz discusses the diagnosis and treatment of this widely underdiagnosed disease with Dr. Peter Green, director of the Celiac Disease Center at Columbia University.

What is it? Celiac disease is an ailment where you have an inflammation in your gut related to glutens, the term for the storage protein of wheat. That inflammatory process erodes the lining of your intestine so it doesn't have the absorptive surface you need to bring key nutrients into the body.

What are the symptoms? Dr. Green says the most common symptoms are abdominal pain, bloating, constipation and/or diarrhea. Other common manifestations are anemia (an iron deficiency), chronic fatigue and even osteoporosis, especially in males or premenopausal females. In addition, you could have dental enamel defects that appear as white or brown spots or bands on your teeth.

How is it diagnosed? Dr. Green says it's very easy to establish a diagnosis with sensitive and specific blood tests. If blood test results are positive, patients are referred to a gastroenterologist for an endoscopy followed by a biopsy to confirm the diagnosis.

How is it treated? Dr. Green says patients begin to see dramatic improvement in a matter of weeks simply by following a gluten-free diet. People with celiac disease should avoid wheat, rye and barley products, and foods such as bread, pasta and beer.

• Celiac Disease: A Hidden Epidemic by Dr. Peter Green

What's your RealAge? Take the test to find out. RealAge