Why a gluten-free diet might be bad for your health

sliced loaf of multigrain bread

Tianna Nadalin

Posted July 08, 2019

First it was fat, then carbohydrates; now gluten has become public enemy number one.

Carbohydrates have long been on the diet naughty list and these days, thanks to a new wave of celebrity-inspired wellness propaganda, gluten is off the plate, too. 

With everyone from Pete Evans and Katy Perry to Gwyneth Paltrow, Lady Gaga and Jessica Alba swearing off cereal grains, it’s easy to see why gluten has become public enemy number one.

People are so confused about whether or not it’s safe to eat that search queries for gluten and gluten-free on Google have more than quadrupled over the past decade. While the incidence of coeliac disease (where the immune system reacts abnormally to gluten causing small bowel damage) remains unchanged, there are an estimated four million Australians who currently live with an allergic disease.

But despite a very public smear campaign against gluten, Monash University nutrition scientist Jane Muir says going gluten-free if you don’t need to might not be the health fix many of us believe.   

“Gluten has been blamed for lots of things over the years,” Jane says. “It’s become a bit of a scapegoat for a whole host of health ailments. The thing is, if you go on a diet where you’re excluding gluten, you’re essentially going to have major impact on your overall diet.”

A 2017 study published in the The BMJ found that, for people who don't have coeliac disease or a true gluten allergy or sensitivity, avoiding dietary gluten may result in a lower intake of whole grains, which are associated with cardiovascular benefits. 

According to the research, adopting a gluten-free diet may even contribute to increased cardiovascular risk. The study said wholesale avoidance of gluten was not recommended for asymptomatic individuals.  

But what is gluten and why is it bad for some people? Here is everything you need to know about the much-maligned cereal offender. 

assortment of pastries and bread at a cafe

Going fluten-free can be a hard decision, so make sure it's right for you.

Gluten 101: A beginner's guide

What is gluten?

Put simply, Jane says, gluten is a protein or, more accurately, a group of proteins found in various cereal grains, including wheat, barley, rye, oats and spelt.  

“Gluten is an incredible protein because it provides unique elasticity, stretchiness and strength qualities to baking and bread,” Jane explains. “It needs water to be activated – and needs to be worked.” 

What foods contain gluten?

These days, gluten is ubiquitous. From breads, pastas and couscous to soy sauce, beer, many mustards, pre-packaged sauces, salad dressings and even chocolate bars and icecreams, gluten is in everything. That means avoiding it isn't as easy as simply skipping that smashed avo on toast for breakfast.

Is gluten bad for you? 

Gluten can trigger adverse inflammatory, immunological and autoimmune responses in some people, such as those with coeliac disease, which occurs in one to two per cent of the population. 

Do I need to avoid gluten?

“Whether or not it is safe to consume gluten depends on your genetics and your gut,” Jane says. “There are people who have an intolerance to gluten. The most common and well understood is coeliac disease, which is an autoimmune condition that affects the small intestine. It is an immune response to the gliadin component of gluten. There is a toxic amino acid sequence within the gliadin that is poorly digested and evokes an immune response in certain individuals. It’s the immune response that causes the reaction.”

Coeliac disease has been linked to increased risk of certain health problems and even 50mg, equivalent to the size of a breadcrumb, can be toxic to those with the disease. 

However, beyond those living with coeliac disease or a diagnosed gluten sensitivity, it is estimated that an additional 10-15 per cent of the population is avoiding gluten as they believe it causes them symptoms.

“Those people should first go to their doctor to check that they don’t have undiagnosed coeliac disease,” Jane says. “Otherwise, don’t be frightened of having gluten or wheat-containing foods. If you don’t have a gut issue, you should still be trying to include whole grains and cereals as part of a healthy, balanced diet.”

What are the symptoms of gluten intolerance/coeliac disease? 

Some of the most common symptoms for coeliac disease include abdominal pain, bloating, flatulence, nausea and vomiting, weight loss (due to poor nutrient absorption), tiredness and chronic anaemia. If you have symptoms, see your doctor. 


field of wheat

Cutting out gluten may result in weight loss, but it's usually related to the absence of certain carbohydrates in your diet. 

What about fructan? 

Fructan is a carbohydrate that is part of the FODMAP family – an umbrella term for group of short-chain carbohydrates. It can trigger a range of gut symptoms in people who don't have the enzymes to digest it. Once it reaches the bowel, bacteria ferment it. This produces gas. Gas causes bloating and indigestion, and can lead to abdominal pain and discomfort. 

“We often have people who come to us complaining of gut symptoms – such as fatigue, bloating etc – that they have identified from eating wheat and gluten-containing products,” Jane says. “They find if they go gluten free they feel better, therefore assume it must be gluten causing the problems. We’ve found, however, that in many cases, the symptoms these people are describing are in response to fructan, which is present in many gluten-containing foods, rather than the gluten. By choosing gluten-free products, they’re choosing low-FODMAP by default, which is often why their symptoms seem to reduce.”

Are gluten-free diets healthier? 

It’s a myth that adopting a gluten-free diet is always healthier.

“You’re cutting out an important food group that is also very high in fibre, as well as potentially missing out on other minerals such as iron, zinc, folate, niacin, thiamine, riboflavin, calcium, vitamin B12 and phosphorus, so you have to be very careful to make sure you’re still achieving a balanced diet,” Jane says. “Plus, gluten-free substitutes are generally made from corn or rice-based flours, have more refined carbohydrates, are lower in fibre and higher in fat and sugar as a way for manufacturers to make them taste better.”

Whenever I give up gluten, then start eating it again, I always feel worse. Why is that? 

If people avoid gluten – and, therefore, fructans – then start eating it again, they can experience digestive issues because of all the fructans they’re consuming

“If you have a healthy gut you’ll be fine, but if you have a functional gut disorder, you’ll probably be uncomfortable,” Jane says. “If you think it might be a problem – reintroduce foods slowly so that you don’t overwhelm your gut.”  

Will I lose weight if I give up gluten?

People often cite weight loss as a by-product of going gluten free. In reality, though, Jane says, this is more likely because people are removing carbohydrates in general, rather than gluten specifically. 

“If you cut out a major food group, which is a carbohydrate group, it’s a way of restricting energy intake,” she explains. “Then people lose weight and feel good because they have lost weight and, again, attribute this to the gluten.”

There is also the risk that gluten-free alternatives are often more refined, higher in sugar, less nutritious and more kilojoule dense, so if you're swapping your regular wheat-based pasta for a gluten-free one, you might actually end up consuming more calories and putting on weight, rather than losing it.  

Are some forms of breads better than others? 

While there is some evidence to suggest sourdough products are easier digested for people with fructan sensitivity, as a general rule, Jane recommends consuming a range of whole grains from sources such as whole wheat, oats, rye, barley, brown rice, wild rice, buckwheat, millet, and quinoa.

“We don’t want people to be frightened of gluten if they really don’t need to be. If you have got major gut issues go to your doctor and get it checked out.”