According to a 2013 survey, a third of Americans actively try to avoid gluten.
But celiac disease, the most severe form of gluten intolerance, only affects 0.7-1% of people ().
However, there is another condition called "non-celiac" gluten sensitivity ().
It involves an adverse reaction to gluten, in people who do not have celiac disease.
This condition frequently comes up in discussions about nutrition, but is highly controversial among health professionals.
This article takes a detailed look at gluten sensitivity and whether it is something you really need to be concerned about.
Before we continue, let me briefly explain what gluten is.
Gluten is a family of proteins, found in cereal grains like wheat, spelt, rye and barley. Of the gluten-containing grains, wheat is the most commonly consumed, by far.
The two main proteins in gluten are gliadin and glutenin, of which gliadin appears to be the biggest offender (3, ).
When flour is mixed with water, the gluten proteins cross-link to form a sticky network that is glue-like in consistency ().
If you've ever held wet dough in your hands, then you'll know what I'm talking about.
The name glu-ten is actually derived from these glue-like properties.
Gluten makes the dough elastic, and gives bread the ability to rise when heated by trapping gas molecules inside. It also provides a satisfying, chewy texture.
Bottom Line: Gluten is the main protein in several types of grains, including wheat. It has certain properties that make it very popular for making bread.
There are numerous disease conditions that are related, either directly or indirectly, to wheat and gluten (6).
The best known of these is called celiac disease ().
In celiac patients, the immune system mistakenly thinks the gluten proteins are foreign invaders, and mounts an attack against them.
Additionally, when exposed to gluten, the immune system starts attacking natural structures in the gut wall, which can cause severe harm. This "attack against self" is why celiac disease is classified as an autoimmune disease ().
Celiac disease is serious business and is estimated to affect up to 1% of the US population. It seems to be on the rise, and the majority of people with celiac disease do not know that they have it (9, , ).
The condition "non-celiac" gluten sensitivity (referred to here as gluten sensitivity) is of a different nature than celiac disease (12).
It doesn't have the same mechanism, but the symptoms are often similar in many ways, and may involve both digestive and non-digestive symptoms (13).
Then there is also wheat allergy, which is relatively rare and probably affects under 1% of people (14).
Adverse reactions to gluten have been linked with numerous other diseases, including a type of cerebellar ataxia called gluten ataxia, Hashimito's thyroiditis, type 1 diabetes, autism, schizophrenia and depression (15, , , , , , ).
This does not mean that gluten is the main cause of these diseases, only that it may make symptoms worse in a subset of people who have them.
In many cases, a gluten-free diet has been shown to be helpful in controlled trials (real science), but this needs to be studied a lot more.
If you don't believe me, just check out the references above. Although far from being definitively proven, these concerns are very real and should be taken seriously.
Bottom Line: Several disease conditions are related to wheat and gluten consumption. The most common ones are wheat allergy, celiac disease and non-celiac gluten sensitivity.
In recent years, gluten sensitivity has received a ton of attention, both from scientists and the public ().
Put simply, people with gluten sensitivity experience symptoms after ingesting gluten, and respond positively to a gluten free diet, after celiac disease and wheat allergy have been excluded.People with gluten sensitivity usually do not show any changes in their gut lining, or antibodies against the body's own tissues, which are some of the key features of celiac disease (12).
Unfortunately, the mechanism behind gluten sensitivity hasn't been clearly established, but this is an area of intense research. There is some evidence that genetics and the immune system are involved ().
There is no reliable lab test to diagnose gluten sensitivity, and the diagnosis is usually made by excluding other conditions.
This is one proposed diagnostic criteria for gluten sensitivity ():
- Gluten ingestion rapidly causes symptoms, either digestive or non-digestive.
- Symptoms disappear quickly on a gluten-free diet.
- Reintroducing gluten causes the symptoms to appear again.
- Celiac disease and wheat allergy have been ruled out.
- A blinded gluten challenge test should be done to fully confirm the diagnosis.
One study showed that in people with "self-reported" gluten sensitivity, only 1 in 4 (25%) satisfied the diagnostic criteria (24).
Gluten sensitivity has numerous symptoms. According to studies, these symptoms include bloating, flatulence, diarrhea, stomach pain, weight loss, eczema, erythema, headache, bone and joint pain, chronic tiredness, fatigue and depression (25, 26).
Also keep in mind that gluten sensitivity (and celiac disease) often have various mysterious symptoms that can be hard to link with digestion, including skin problems and neurological disorders (, ).
There is actually no good data available on how common (or rare) gluten sensitivity is. Some studies show that as little as 0.5% of people may have this condition, while others go as high as 6% (6).
Bottom Line: Gluten sensitivity involves adverse reactions to gluten in people who do not have celiac disease or wheat allergy. No good data is available on how common it is.
One recent study on gluten sensitivity is worth highlighting here.
This study was done on 37 people with irritable bowel syndrome and self-reported gluten sensitivity ().
What this study did differently than the ones before it, is that it placed the participants on a diet low in FODMAPs (FODMAPs are short-chain carbohydrates that can cause digestive issues).
Then they gave them isolated gluten instead of a gluten-containing grain, like wheat.
In this study, isolated gluten did not have any effect on the participants, except for an increase in symptoms of depression in a follow-up study, which needs to be researched further ().
The conclusion of the study was that isolated gluten did NOT cause problems in these individuals, and that this self-reported "gluten sensitivity" was more likely to be a sensitivity to FODMAPs.
This study made headlines all over the world, claiming that gluten sensitivity had been disproved and that gluten was safe for anyone except people with celiac disease.
However, this is completely false. What this study does show, is that gluten probably isn't a very big factor in irritable bowel syndrome, in which case FODMAPs are the main player.
This study also happens to support the fact that many people (IBS is very common) are intolerant to wheat, and should make an effort to avoid it. It's just that the mechanism is different from what was previously believed.
The solution, a gluten and wheat-free diet, is still the same, and just as effective as before.
This has led many researchers to speculate that perhaps "wheat sensitivity" or "wheat intolerance syndrome" are more appropriate labels than "gluten sensitivity" (, 30).
Although this hasn't been researched as thoroughly, there are also some studies suggesting that modern strains of wheat are more aggravating than ancient varieties like Einkorn and Kamut (, ).
Bottom Line: A new study shows that, in people with irritable bowel syndrome, a class of carbohydrates called FODMAPs are the main cause of digestive problems, not gluten itself.
Gluten sensitivity is more than just some made up nonsense.
There are hundreds of papers in the literature on this. Just try typing "gluten sensitivity" into or Google Scholar.
There are also tons of scientists and medical doctors, including many respected gastroenterologists, who are convinced that this is real.
True, there is no evidence that everyone needs to avoid gluten, and there is definitely a "fad component" to the gluten-free trend.
However, gluten (or wheat) sensitivity IS a real thing, and it does cause problems in many people.
Unfortunately, this condition is incredibly complicated, and very few clear answers have been discovered yet.
Gluten and wheat may be fine for some people, not others. Different strokes for different folks.
But if you are personally convinced that wheat/gluten causes you problems, then there's no reason to sit around and wait for the research to come in.
If it makes you feel bad, just avoid it. Plain and simple. There is no nutrient in there that you can't get from other (often much healthier and more nutritious) foods.
Just make sure to choose real foods that are naturally gluten free, not gluten-free products. Gluten free junk food is still junk food.