Gluten Intolerance is an umbrella term including any negative reaction to gluten ingestion that includes an immune response. It includes: celiac disease (CD), wheat allergy and gluten sensitivity. If you have celiac disease, you are gluten intolerant, however, you may be gluten intolerant, but not have celiac disease.
Celiac Disease (CD)
CD is not a food allergy. It is an autoimmune disease where your body attacks itself resulting in intestinal damage, malabsorption of nutrients, and nutritional deficiencies. CD increases your risk of other autoimmune diseases, increases risk of malignancies or cancers, may cause neurological conditions, and is hereditary. It is treated with a gluten-free diet.
Gluten Sensitivity (GS) or Non-Celiac Gluten Sensitivity
Gluten Sensitivity or as most doctors refer to it as Non-Celiac Gluten Sensitivity (NCGS), is considered a non-autoimmune reactions to gluten ingestion. Typically, sensitivity refers to lacking an enzyme to digest that nutrient or eating too much of that nutrient. People with GS do not have a wheat allergy or CD, but still present with adverse symptoms after the ingestion of gluten. The small intestine of GS patients is usually normal. As of yet, there are no screening tests, blood markers or defined set of symptoms for gluten sensitivity. The most common symptoms are abdominal pain, bloating, diarrhea, constipation, anemia, headaches, numbness and depression, but more than 100 symptoms have been loosely linked to gluten intake. A gluten-free diet is the only recommendation for GS, although some may be able to tolerate small amounts of gluten without a deleterious effect. NCGS is only diagnosed by excluding both celiac disease, and an IgE-mediated allergy to wheat, and by the presence of adverse symptoms from gluten consumption.
Wheat Allergy (WA)
Wheat Allergy is an allergic reaction to wheat where the body produces antibodies in response to wheat ingestion. Unlike CD which is characterized by a delayed immune reaction, WA produces an allergic response that is immediate -- within seconds or up to several hours. The immune system recognizes wheat as an antigen, causing the release of chemicals or histamines that are responsible for the allergy symptoms. Like other food allergies, the symptoms of WA may include hives, itching, nasal congestion, nausea, vomiting, throat tightening, swelling and anaphylaxis. WA is not an autoimmune disease. If you have a wheat allergy you need to avoid wheat products.
Adapted from University of Chicago Celiac Disease Center