But a pesky question keeps coming up, challenging these assumptions: For those who don't have coeliac disease, which is about 98 per cent of us, is gluten really a problem and does gluten-intolerance actually exist?

As a recent, hilarious piece from the US TV show Jimmy Kimmel Live highlighted, the public is largely puzzled by gluten and why exactly they need to avoid it.

''Some people can't eat gluten for medical reasons, which that I get. It annoys me but I get it,'' Kimmel mused. ''But a lot of people don't eat gluten because somebody in their yoga class told them not to.''

Indeed. A new study found more than a quarter of respondents with self-reported non-coeliac gluten sensitivity (NCGS), don't fulfil criteria for its diagnosis.

The Australian market for gluten-free is set to hit more than $100 million in the next year while products pitched as ''gluten-free'' are often more than twice as expensive, even compared to their gluten-free counterparts that have not cashed in by marketing themselves as such.

A spate of contradictory studies about how pernicious gluten actually is only adds to consumer confusion.

Last week, author and health guru Chris Kresser wrote a rebuttal to the glut of recent articles slating gluten sensitivity as 'bullshit'.

The articles have come on the back of an Australian study published last year which found that it may not be gluten causing gut problems in people with supposed sensitivities.

Instead of gluten, a protein found in wheat and some other grains including barley and rye, the study suggested that short-chain carbohydrates called FODMAPs (Fermentable Oligo-saccharides, Disaccharides, Mono-saccharides andPolyols) might be leading to symptoms such as bloating and gut distress.

The study's author, Peter Gibson, of Melbourne's Monash University, originally published a paper providing evidence that gluten-sensitivity exists. 

That was in 2011. Last year he decided to do a follow-up study using tighter controls. 

Over the course of five weeks, all meals were provided for the 37 subjects with self-diagnosed NCGS and irritable bowel syndrome (IBS). While keeping a daily diary and undergoing tests, the participants were rotated through gluten-free, low-gluten and high-gluten diets. The common factor across all three diets was that they were all low in FODMAPs, which are found naturally in wheat as well as other foods as varied as apples, onions, milk and mangoes. 

In contrast to his 2011 study, Gibson said, ''we could find absolutely no specific response to gluten''.

''In all participants, gastrointestinal symptoms consistently and significantly improved during reduced FODMAP intake, but significantly worsened to a similar degree when their diets included gluten or whey protein,'' Gibson wrote. ''Gluten-specific effects were observed in only 8 per cent of participants.''

The worsening symptoms, even while on the placebo diet, could be explained by a nocebo effect, Gibson said, where we feel worse when we expect to feel worse. 

As for people mistakenly believing they are gluten-sensitive, Gibson suggested that the reason participants felt better for avoiding wheat was because of its high percentage of FODMAPs.

In his response to the study and the articles that ensued, Kresser wrote: ''This is a significant finding, but to claim it proves that non-coeliac gluten sensitivity doesn’t exist is both inaccurate and irresponsible. It’s a great way to get clicks and generate attention, but it’s an extreme distortion of what the study actually found.''

Among other things, to determine whether gluten or FODMAPs are causing you gut troubles, Kresser suggests removing all gluten for 60 days and then having a bowl of barley, which he says is low in FODMAPs, followed several days later by a piece of wheat bread.

Gibson argues that Kresser's response is ''well written but so wrong in several key facts'' and is just ''another misinterpretation of what was a straightforward message''.

He points out, for instance, that using barley to determine gluten sensitivity is inaccurate as barley is very high in FODMAPs.

''What our study has shown is that, in people with gut symptoms who have had some relief with the gluten-free diet, it is not the gluten that is the culprit, but it is more likely to be FODMAPs,'' Gibson says now.

''It does not say that there is no such thing as non-coeliac gluten sensitivity. It is just we could not see any evidence of it in the 37 patients we studied, all of whom fulfilled the current definition of NCGS.

''Why gluten has been blamed is that people do often improve with a gluten-free diet because wheat, rye and barley, the three cereals that contain gluten, all have high amounts of FODMAPs in them.

''Unfortunately, wheat has been recognised as containing gluten and, with the media hype and film stars etc pushing gluten-free, it is quite understandable that people think it is the gluten that was the villain. Wheat contains more than just gluten.''

That said, Gibson is not letting gluten off the hook. In April, he and his team published another study exploring the link between gluten and depression. 

He believes people may report improvements on a gluten-free diet because it makes them quite literally ''feel better''.

''These findings are only preliminary and the proper study is now being performed on the basis of the suggestions from the pilot,'' Gibson says. ''It may be that people with gut symptoms feel better on the gluten-free diet because they are less depressed. We must await the detailed study to see if this is true.''

GETTING TO THE GUTS OF GLUTEN

Gluten is not in all grains: Assuming they haven't been contaminated, rice, corn and popcorn, quinoa, amaranth, buckwheat, millet, sorghum and oats are all naturally gluten-free.

Gluten-free does not mean more natural: As well as often being more expensive, gluten-free foods are often as highly processed as products containing gluten.

Gluten is not just in wheat: As well as bread, pasta, barley and rye, it is also often found in salad dressings, vitamins and seasonings.

Coeliac disease: Is an autoimmune enteropathy triggered by the ingestion of gluten. Gluten-sensitive individuals cannot tolerate gluten and may develop gastrointestinal symptoms similar to those in CD, but the overall clinical picture is typically less severe.

Gluten sensitivity: Refers to an adverse reaction to eating gluten that usually does not lead to damage of the small intestine.

Wheat allergy: Is not specifically related to the gut. Reactions to wheat can vary significantly and like other classic food allergies can affect the skin, gastrointenstinal tract or respiratory tract.

Coeliac: Denotes a response to gluten that causes the immune system to attack its own body tissue.