Coming to the first part of your question, Gluten Intolerance or Celiac Disease is a hereditary problem affecting the immune system. The consumption of gluten destroys the lining of the small intestine called mucosa. Consequently, essential vitamins and nutrients are not properly absorbed. As for as the second part of your question, Grains like wheat, barley, rye, and low level oats contain a rubbery substance called gluten, which is a protein that helps in binding the dough. It is commonly used in baked breads and other baked foods. Though gluten causes gluten allergy in sensitive people, there are many other proteins that can trigger allergic symptoms. The symptoms and intensity of the symptoms of gluten allergy can differ from person to person. But the general symptoms are hives, swelling, abdominal cramps, nausea and vomiting, or asthma. For a person extremely sensitive to gluten allergy, the symptoms can be fatal. So We advice you to take precautions about your diet. You can visit a nutritionist to plan for gluten free diet.