Nearly five times as many Americans have celiac disease today than in the 1950s, a recent studyof 9,133 young adults at Warren Air Force Base found. Another recent report found that the rates of celiac disease have doubled every 15 years since 1974. The debilitating digestive disease is now estimated to afflict about 1 in 100 Americans. Why is exposure to gluten--a protein in found in barley, wheat, rye, and possibly oats, as well as other everyday products, including some brands of lipstick, vitamins and lip balms�making more people sick than ever before?

To find out more about celiac disease and the health effects of gluten-free diets, I talked to Christina Tennyson, MD of the Celiac Disease Center at Columbia University in New York City.