Doctors have always talked about gluten in terms of the damage it does to the intestine in celiac disease. Always is actually a relative term, going back to just the 1940s when it was discovered that the damage could be linked to wheat. Children with celiac disease were dying of malnutrition. But then the mortality rate dropped when wheat famine hit northern Europe. And it returned when the famine was over. So wheat was taken out of these children's diets (and all the other diets that had been used, restricting children to fruits or mussels were stopped).
Celiac disease is diagnosed by a combination of blood tests and an intestinal biopsy. In celiac disease, part of the intestine shows flattening or disruption of the surface when it has really taken hold; or in mild cases, certain cells invade the structures. And typically, antibodies show up in blood tests, reflecting those changes (more about that in another post).
The problem (or the good news, perhaps) is that not all those who are sensitive to gluten have celiac disease. We've learned that from patients who have started gluten restricted diets and feel better even when they haven't been diagnosed with celiac. So that's lead to an entirely new category: non-celiac gluten sensitivity.
Non-Celiac Gluten Sensitivity
First, there are those who have wheat allergy--and that's a separate category. They have true wheat allergy showing up on skin or reliable blood tests (notice the adjective, since there are lots of tests out that are not reliable). And when that person has wheat, they react with a rash or discomfort for example). They may have other allergies showing up with testing, but they don't usually have a reaction to the other grains (rye, barley and spelt) that are involved with gluten sensitivity.
So that once celiac disease and wheat allergy are excluded, patients who have gluten sensitivity can be recognized with this newly coined condition. This includes some patients with irritable bowel syndrome (IBS or spastic colon, which is a different name for the same thing), some patients with autistic spectrum disorders, chronic fatigue or long-term intestinal complaints.
The important point is that celiac disease and what allergy should be ruled out first with proper testing (while the person is still taking gluten), otherwise it is more difficult to make the diagnosis--and the diagnosis makes a difference in how rigid and restrictive the diet needs to be. The patient with celiac disease needs to devoted to their diet to prevent life-long consequences, while the patient with wheat allergy only needs to focus on eliminating wheat. And someone who has the non-celiac variety can be cautious, but can discuss with their doctor how restrictive they should be..
How Do You Know Whether You Have Non-Celiac Gluten Sensitivity?
Once the other conditions have been looked for and dismissed the only way to tell, at present, is to go on a strict gluten-free diet for 3-4 weeks. Some will notice an improvement right away. In others, especially those in the autistic spectrum, it may take several weeks to see a change. However, if there isn't any difference in a month, it's unlikely there will be one -- and you can assume you are not gluten sensitive.