Gluten intolerance, often referred to as gluten sensitivity or nonceliac gluten sensitivity, is caused by a reaction to gluten. It is similar to celiac disease -- an autoimmune condition -- but is not as serious. Both have similar symptoms, but celiac disease can cause permanent damage if left untreated. No evidence suggests that a connection exists between a gluten intolerance and respiratory disorders, but some smaller studies have shown celiac disease may be correlated with certain respiratory problems. It's also possible that an allergy to wheat -- a gluten-containing grain present in a variety foods -- or, very rarely, an allergy to gluten is to blame, as food allergies do affect the respiratory system. Only a qualified health practitioner can offer a proper diagnosis and treatment.
The term gluten actually refers to a group of proteins commonly found in some grains. These proteins are present in all varieties of wheat including durum, semolina, spelt, kamut, einkorn and faro, as well as other related grains, such as rye, triticale and barley. Gluten is helpful in baking because it creates a stronger, stringier dough and helps to capture air produced by yeast or other leavening agents, which helps breads and other baked goods fill out or rise. Humans don't digest gluten very well, but only a certain percent of the population has a gluten sensitivity or celiac disease.
A gluten intolerance is caused by a reaction to gluten based on the innate immune response, which is the body's basic defense mechanism against what it perceives as harmful. The innate immune response does not result in the body attacking itself, so it does not cause damage to the body. Celiac disease, on the other hand, is an autoimmune disease, which means that the body attacks its own tissues. In the case of celiac disease, the affected tissue is the villi -- small protuberances in the small intestine responsible for the digestion of nutrients. The symptoms of both maladies are similar and can include gastrointestinal problems, such as bloating or cramping, as well as fatigue, depression, anemia, joint pain, osteoporosis and leg numbness. The feeling of a having a "foggy" head is also common.
Respiratory symptoms are not common with either gluten intolerance or celiac disease, but some studies have shown a possible correlation in the case of celiac. For example, one small case study published in 2008 in "Revue De Pneumologie Clinique" found that a man with celiac disease and recurrent respiratory infections had relief from both issues when he went on a gluten-free diet. Another study published in the April 2011 "Journal of Allergy and Clinical Immunology" reported people who had celiac disease were almost twice as likely to get asthma than those who didn't have the disease.
An actual allergic reaction to gluten is very rare, but an allergy to wheat is very common (ref 8). It can be easy to confuse a wheat allergy with a gluten sensitivity, particularly if you have not been properly diagnosed, as many products contain wheat, and gluten is present in all forms of wheat. Unlike gluten sensitivity or celiac disease, wheat causes an actual allergic response, which can include a variety of respiratory or related symptoms such as nasal congestion, runny nose, sneezing or a slight, dry cough. (ref 9)
The proper treatment for gluten sensitivity and celiac disease is a gluten-free diet, as there is no cure for either problem. It's important to get a proper diagnosis, however, as celiac disease is much more severe and may require other forms of treatment. A qualified health practitioner can also test for a wheat allergy, which requires a different form of treatment than either gluten intolerance or celiac disease and can potentially be fatal in the case of a severe allergic reaction.