Upset stomach is not uncommon. People may experience stomach upset if a meal is too rich or has too many spicy ingredients. However, for some people, routine stomach upset could be indicative of Celiac disease, a condition that's much more serious than periodic indigestion.

The Mayo Clinic says Celiac disease, sometimes called "Celiac sprue" or "gluten-sensitive enteropathy," occurs when the immune system revs up after eating gluten. Gluten is a protein found in wheat, barley and rye grains. For people with Celiac disease, the ingestion of gluten leads to damage in the small intestine. It is estimated that Celiac disease affects 1 in 100 people worldwide, and that 2.5 million Americans are undiagnosed and at risk for long-term health complications, according to the Celiac Disease Foundation.

Celiac disease can develop at any age after a person starts eating foods or taking medicines that contain gluten. Those with a relative, such as a parent, child or sibling, with Celiac disease have a one in 10 risk of developing the disease themselves. If left untreated, Celiac disease can contribute to additional health problems.

Currently there is no medical treatment for Celiac disease, though adherence to a gluten-free diet can reduce if not eliminate flare-ups. People must fully refrain from consuming foods that contain barley, rye and wheat. Depending on the severity of the disease, even ingesting a few crumbs from inadvertent cross-contamination can lead to small intestine damage and pain.

The Celiac Disease Foundation says people who do not take their disease seriously may put themselves at a heightened risk for Type 1 diabetes and multiple sclerosis, among other autoimmune conditions. In addition, skin rashes, anemia, osteoporosis, infertility, and even neurological conditions like migraines or epilepsy may develop if Celiac disease is ignored.

Fortunately for people with Celiac disease, the availability of foods that are gluten-free continues to grow both in supermarkets and at restaurants. People with Celiac disease need not avoid the foods they love thanks to the availability of gluten-free alternatives.