Q: What is gluten? Why are some foods gluten-free?
A: Gluten is a naturally occurring protein found in grains such as wheat, barley, rye, and oats. Its unique structure results in the elastic consistency found in the dough derived from these grains.
Over the centuries, the elastic consistency led to the use of these grains in breads and other baked goods which are staples in most diets.
Some people have intolerance to gluten. Symptoms of the intolerance range from headaches, bloating, diarrhea, weight loss, and malnutrition. People with the worst cases of intolerance are sometimes diagnosed with celiac disease. This is an autoimmune disorder and is characterized by the reduced ability of the small intestine to properly absorb nutrients from certain foods.
A gluten-free diet is prescribed to minimize or eliminate the symptoms of the intolerance. Some foods are naturally gluten-free (including some grains) while others are made to be gluten-free. The link below from the Mayo Clinic provides a list of gluten-free foods.
References:
http://www.celiac.com/
http://www.mayoclinic.com/health/gluten-free-diet/my01140