Celiac disease is a digestive disease that damages the small intestine and interferes with absorption of nutrients from food. People who have celiac disease cannot tolerate gluten, a protein in wheat, rye and barley. Gluten is found mainly in foods but may also be found in everyday products such as medicines, vitamins and lip balms.

Multiple sclerosis (MS) is a chronic, unpredictable disease of the central nervous system (the brain, optic nerves, and spinal cord). It is thought to be an autoimmune disorder. This means the immune system incorrectly attacks the person's healthy tissue.

Bipolar disorder, formerly known as manic-depressive illness, is a brain and behavior disorder characterized by severe shifts in a person's mood and energy, making it difficult for the person to function. More than 5.7 million American adults or 2.6 percent of the population age 18 or older in any given year have bipolar disorder. The condition typically starts in late adolescence or early adulthood, although it can show up in children and in older adults. People often live with the disorder without having it properly diagnosed and treated.