Everything you need to know about gluten intolerance

It seems that more and more grocery stores and restaurants are providing gluten-free options to cater for people with gluten intolerance and coeliac disease. While science has a pretty good understanding of coeliac disease, there’s an ever-increasing group of people where the cause of their symptoms is less certain. 

We asked Dr Joanna Harnett from The University of Sydney School of Pharmacy about gluten intolerance, its causes, and most importantly, what gluten actually is.

What is gluten?

Of course you've heard of it, but do you know what it is?

“Gluten is the protein component of some of the common grains in our diet - wheat, rye, barley and oats. It gives a fluffy texture to a lot of the baked products we might eat, like bread, pastries and cakes," Dr Harnett explained.

What's the difference between coeliac disease and gluten intolerance?

While coeliac disease is caused by an immune response to the gluten protein itself, it’s less clear what causes gluten intolerance.

In people with the disease, the body’s natural protection against infection attacks gluten in the small intestine, causing inflammation and eventually wearing away the intestine’s lining. People with coeliac disease experience a range of symptoms including diarrhoea, cramping, bloating and fatigue.

People with gluten intolerance (or non-coeliac gluten sensitivity) show symptoms similar to those with coeliac disease in response to eating gluten, but test negative for the disease.

We asked Dr Harnett why this is, and why it seems that so many people are becoming gluten intolerance. 

“What we’re beginning to understand is that it’s unlikely to be the whole gluten protein that causes these symptoms in this particular group of people,” says Dr Harnett.

Looking beyond gluten

Instead, it could be caused by a group of fermentable sugars (coined FODMAPs by a team at Monash University) that are found in grains alongside gluten. 

FODMAPs are fermented by bacteria in the gut, releasing gas. These gases draw water into the gut, which causes even more gas to be produced.  This process creates a lot of the same symptoms as coeliac and gluten intolerance - gas, diarrhoea and bloating.

This could explain why these people don’t test positive for coeliac disease and can have inconsistent reactions to products containing gluten.

So, is gluten intolerance is a myth?

Not entirely, says Dr Harnett.

“Certainly, there is a group of people that have a problem with gluten outside of the medical causes of coeliac disease ...  but the percentage of those is thought to be actually quite small.”

If you think you're having symptoms set off by gluten in your diet, it's best to consult with your doctor.

“The important thing is [to] get the correct medical diagnosis so you know exactly what it is you're meant to be excluding. Is it all gluten, is it those fermentable carbohydrates, or more importantly, is there another reason for your symptoms that hasn’t been identified yet.”

Gluten glossary

Quick definitions for all things gluten.

• Gluten: a protein found in cereal grains (eg. wheat, rye and barley) responsible for the elastic texture of dough.
• Coeliac disease: an immune reaction to eating gluten that over time creates inflammation and damages the lining of the small intestine.
• Dermatitis herpetiformis: a chronic skin condition, similar to eczema, that is caused by the immune reaction to gluten in people with coeliac disease.
• FODMAPs: a group of fermentable carbohydrates (sugars). Stands for Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols.
• Gluten ataxia: a rare autoimmune condition where the body’s immune system attacks the nervous system in response to ingesting gluten. Not necessary related to coeliac disease.