27E93C3A-83B9-4595-91CE-57506165869F Created with sketchtool. Science Update: Gluten-Free Diet

Science Update is a monthly written series, curated by Dr Paul Willis, tackling some of the controversial topics in the public and aims to provide the current research behind these subjects. This month Dr Lila Landowski talks about the gluten-free diet dichotomy.

With social media being flooded by headlines like “Why gluten is ruining your life,” “How wheat is slowly killing millions of people,” and “3 hidden ways wheat makes you fat” it is hardly surprising that almost 1 in 10 Australian adults opt for a gluten-free diet. But is there any truth to these claims? Probably not, but it isn’t quite that simple either.

Currently, Coeliac disease is the only medically recognised gastrointenstinal disorder that is specifically associated with gluten consumption. Coeliac disease is a serious autoimmune disorder that affects 1 in 100 people. Trace amounts of gluten – a breadcrumb – would be sufficient to induce severe diarrhoea and fatigue in persons with Coeliac disease. It is possible to be allergic to wheat, but this allergy results from wheat-specific proteins (ie. not gluten, as this is not exclusively found in wheat). For these people with wheat allergies, this means it is possible to eat gluten from non-wheat sources without any ill effects.

But what about gluten sensitivity or gluten intolerance? The first compelling evidence that non-Coeliac gluten sensitivity existed was reported in 2011 by a team from Monash University. This led to the meteoric rise of the gluten-free diet. However, in a spectacular turn of events, their 2013 follow-up study (which was more rigorous than the first) showed that persons with self-evaluated gluten sensitivity had no evidence of reactivity to gluten. In fact, the researchers detected a nocebo effect: patients responded the same way regardless of the diet, suggesting that the effect was psychologically driven rather than based on a biological response to something within the food. Although the researchers debunked their original findings, and the very existence of gluten sensitivity remains controversial*, the idea of gluten sensitivity persists in popular culture.

Gluten is a protein found in wheat, barley, rye and other grains. It is important for the texture and taste of many foods – it gives bread that spongy elasticity, and it makes your favourite mock meat deliciously chewy. The body doesn’t digest gluten, but your intestinal bacteria do. In response to gluten, intestinal bacteria will generate metabolic by-products such as gas, so it is normal to feel a little bloated after a gluten-rich meal of pasta or bread. Given that the populations of gut bacteria vary between individuals, the response of an individual to gluten subtly varies too. This normal phenomenon may be the root of some misguided self-diagnoses of gluten sensitivity.

But does that mean gluten sensitivity doesn’t exist? Although the science is in its infancy, it appears likely that a proportion of the population have a reaction to short-chain carbohydrates – more specifically, Fermentable, Oligo-, Di-, Mono-saccharides And Polyols (collectively called FODMAPS). FODMAPs can trigger symptoms like bloating, wind or cramps in sensitive individuals. These people would be diagnosed with irritable bowel syndrome. When you consider that short-chain carbohydrates are found in wheat-based products, this may explain why some people may experience a reduction in symptoms whilst going on a gluten–free diet.

Given the unfortunate abundance of pseudoscience articles demonising gluten, the gluten-free diet poses itself as an attractive solution for people who want to improve their lives. But is going on a gluten-free diet good for you, regardless of your gut reaction to gluten? Some recent converts to a gluten-free diet may claim to initially feel better, though this is likely due to the individual making more health conscious choices as a result of transitioning to a new diet. Gluten-free food options are generally not healthier, and typically contain higher amounts of fat and sugar, and less fibre, than their gluten-containing counterparts. To make matters more confusing, unhealthy gluten-free food is often lumped in with health food – but a gluten-free treat is still a treat. Weight gain/obesity, metabolic syndrome and type II diabetes have all been associated with long-term adherence to gluten-free diets. Gluten-free diets often lead to a number of vitamin deficiencies (such as folate, iron and magnesium), and increases the risk of mercury toxicity. For those who follow a gluten-free diet because they believe it to be healthier, it may be time to reconsider.

Despite there being no indication for a gluten-free diet outside of Coeliac disease, the gluten-free fad is big business and doesn’t look to be going any time soon. Whilst there is a time and place for trusting our gut feeling, when it comes to matters of gut irritability, see a doctor before self-administering a gluten-free diet. If you have an underlying condition like irritable bowel syndrome, a gluten-free diet may make your condition worse in the long term. And whatever you do, don’t ignore the science.

*Author's note: There's been another big study since the Monash one althought there are some doubts about the validity of the results. It was not as well controlled and the authors have a conflict of interest – they have a patent out that covers gluten sensitivity testing kits and profit from the idea that gluten sensitivity exists.

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About the Author

Lila Landowski
Neuroscientist, university educator, science communicator & advocate. Premier's Young Achiever of the Year 2015. Twitter: @rockatscientist


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