I’m trying to explain the difference between coeliac disease and wheat intolerance to a coworker and while I understand the complexities of coeliac disease and how it can effect different people to different levels, I struggled when he asked me to explain the key differences between the disorder and an allergy.
In: Biology
Autoimmune is when your body attacks itself.
Allergy is when your body overreacts to some external factor (eg. dust in the air, or nuts in your food).
Gluten/wheat is usually something else – *intolerance* where body can’t properly process something, and is reacting negatively to it (but not *over*reacting like in case of an allergy).
PS. There are exceptions, and distinction isn’t always so clear, but that’s the rule of the thumb.
I’m going to be doing a few podcast episodes on this stuff, so I’ve been reading up on it a lot.
Allergy is a certain kind of immune overreaction to a harmless external substance. Allergies typically have a kind of antibody response (IgE) and commonly involves certain immune cells (mast, eosinophils, basophils). The substance being “harmless” is an important part of the idea — not everyone reacts in to that substance and the substance doesn’t cause you damage outside of your immune overreaction. The substance being from outside your body is also important and is a major distinguishing factor between allergy and autoimmune.
An autoimmune issue is also an immune overreaction/mistake. In this case, though, your immune system is overreacting to a normal thing inside your body. Antibody responses are around, but you see more types of antibody (IgE, IgG, IgM). You also see a lot of different immune cells involved, like heavy involvement of T cells. A major point here is the thing your immune system is going after is something your own body makes.
An interesting cross-over point here is that one way your immune system can make the “autoimmune mistake” is if it is launching an immune response to something else, but then getting that other thing mixed up with something in your body. This is called “molecular mimicry”, and at least in some cases this is how autoimmune problems get started — so your immune system could start getting mad at gluten, but then confuse gluten for transglutaminase 2 (TG2). Then your immune system gets all mad about TG2 and starts attacking cells with it, namely cells in your intestinal lining.
I usually type up long comments here but I’ll try to keep this ultra brief.
In an autoimmune disease, the sensors on your immune cells get triggered by things in your body, like proteins on the surface of some cells. Upon activation they recruit many other immune cells and begin attacking the target to destroy it, confusing it for a foreign body. So your body ends up destroying some part of it and it manifests as the disease.
In an allergy, the sensors get hyperactivated by foreign yet innocuous or harmless substances. So the immune cells things it’s a foreign enemy that will hurt you and needs to be destroyed, and so they summon a large force of the immune system to combat this enemy. And in the process, it could kill you due to the complications caused by this excessive reaction (like swelling due to the release of so many signal molecules to make your blood vessels locally leaky, to help the immune cells mobilize towards the battle site, and this swelling can sometimes be life threatening like when it’s in the tongue or throat blocking your breathing for example, and this is just one example of the complications).
There are 3 possibilities: celiac disease, allergy to wheat, or sensitivity to gluten.
Celiac disease requires NO gluten (from wheat or other sources). Eating any amount of gluten will make the person sick and will damage their small intestine.
A wheat allergy means a person can’t eat wheat (but may be able to eat other foods with gluten). Eating wheat may result in a life-threatening reaction (just like a peanut or shellfish allergy).
Being sensitive to gluten means that a person may be able to eat some gluten but if they eat too much, they will feel sick. They aren’t doing any permanent damage to their inner organs, though.
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