Is It the Gluten or the FODMAPs? – A Confusion, Explained

Published on: 02/11/2019

Is It the Gluten or the FODMAPs? – A Confusion, Explained

A common misconception about the low FODMAP diet is that it is a gluten-free diet. This is understandable as you need to mostly eliminate gluten-containing grains – wheat, barley, and rye – during the elimination phase. For some people, these foods trigger digestive symptoms such as gas, bloating, abdominal pain, constipation, or diarrhea.

But, what is it in these foods that is triggering the symptoms? The gluten, or the FODMAPs? That’s what I am going to explain in this blog post. I will clarify why the low FODMAP diet is not a gluten-free diet and how you can still eat some gluten-containing foods without tummy troubles.

Gluten and FODMAPs: what’s the difference?

Gluten is the main protein in wheat, barley, and rye. People with celiac disease need to avoid it completely. Furthermore, people with non-celiac gluten sensitivity (NCGS) – a newly recognized condition that occurs when someone has a reaction from eating gluten but does not have celiac disease or a wheat allergy – also feel better when avoiding these grains and their products. Celiac disease and NCGS are typically diagnosed by a gastroenterologist. Finally, people with a wheat allergy need to avoid all varieties of wheat (including spelt, kamut, einkorn, farro/emmer, and triticale).

FODMAPS, on the other hand, are carbohydrates. Gluten-containing grains contain a type of FODMAP called fructans (within the larger category of oligosaccharides, the “O” in FODMAPs). The common confusion comes from the fact that both gluten and fructans co-exist in wheat, barley, and rye. The reason you need to mostly eliminate these grains in the low FODMAP diet is that the fructans are poorly digested in people with IBS and may trigger symptoms. During the elimination phase, gluten-free grains like rice, quinoa, buckwheat, and millet become a staple.

However, you can still eat some authentic sourdough bread. That’s because the live cultures literally “digest” the fructans for you during a long process of fermentation, which reduces the fructan content of the bread. In addition, you can have soy sauce and even one small slice of regular wheat bread, as the fructans level is low enough that they are considered low FODMAP. In other words, the low FODMAP diet is not a gluten-free diet.

Not all gluten-free products are low in FODMAPs

During the elimination phase of the low FODMAP diet, people rely on gluten-free grains and some gluten-free alternatives to bread, pasta, crackers, and cookies and assume they are also low in FODMAPs. However, gluten-free doesn’t necessarily mean low FODMAP. In fact, when looking at a gluten-free product, you need to become an expert label reader. Although the main flours used are low FODMAP (rice, tapioca, cassava), there are very often high FODMAP ingredients such as honey, agave, pear or apple juice (used as sweeteners), inulin or chicory (added to increase the fiber content) and others.

Take home message

Many people report feeling better on a gluten-free diet but don’t necessarily know why. Is it because they are sensitive to gluten, or the fructans? If you are one of them, I strongly encourage you to get a proper diagnosis first. If you are diagnosed with celiac disease or NCGS, then you will know that you need to avoid gluten-containing grains and their products. On the other hand, if you have a wheat allergy, you will need to avoid all wheat products. If you don’t have any of these conditions or continue to have symptoms on a gluten-free diet, the fructans (FODMAPs) may be to blame.

In this instance, working with a dietitian to identify the source of the problem may help you liberalize your diet and find that you don’t need to avoid all gluten-containing grains and products. Interestingly, a study from Monash University found that only a small percentage of the subjects who had both IBS and NCGS were indeed sensitive to gluten (8%) but all subjects felt better while eating a low FODMAP diet. This finding suggests that the FODMAPs had the greatest impact on their digestive symptoms.

Trying to figure out what is triggering your IBS symptoms? Unsure whether you are sensitive to gluten or FODMAPs? I can help!

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I’m a registered dietitian with a passion for helping women with IBS find their way back to eating without fear of painful gut symptoms and without unnecessary diet restrictions.

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