People with celiac disease
cannot tolerate to gluten
are unlikely to live past the age of eighteen
can be treated successfully with mega-vitamins
can be treated successfully with newer antibiotics

People with celiac disease cannot tolerate gluten.  Gluten is a type of protein found as nutrient in food and is released to the digestive system. When the body receives food that contains gluten (e.g. wheat, rye, and barley) the immune systems responds and attacks the small intestines. In the event of this, the linings of the small intestine called villi are damaged. When the villi get damaged, the body cannot properly absorb nutrients.

This disease is hereditary, were people with a 1st-degree relative have a 1 in 10 risk of developing this disease.

The answer is joseph is observing the colour of the reaction mixture to see whether proteins are present in the given solution.