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What’s the Difference Between FODMAPs & Gluten

May 12,2019

The low FODMAP diet does remove many grains that contain gluten. But you may be surprised to hear that, in the absence of coeliac disease, it is usually the FODMAPs in wheat that are the problem, not the gluten.

What is Gluten?

Gluten is the general name given to the proteins found naturally in wheat, barley, rye and oats. If a person with coeliac disease eats foods containing gluten, an abnormal immune response occurs which causes damage to the lining of the small bowel. This damage affects the absorption of nutrients potentially leading to abdominal symptoms (e.g. diarrhoea, cramping or nausea), iron deficiency, osteoporosis, fertility problems and even lymphoma. If a person has coeliac disease, currently the only treatment is a strict gluten free diet for life, including care to avoid cross contamination.

What are FODMAPs?

FODMAP is an acronym for four groups of short chaincarbohydrate, or sugar molecules found naturally in wheat, barley, rye, honey, milk, legumes or certain fruits and vegetables. When people with IBS eat foods containing FODMAPs, instead of being absorbed in the small intestine, they pass through intact to the colon. During this process two processes occur:

  1. Certain FODMAPs are highly osmotic and readily draw water into the small and large intestine. This can effect how fast the bowel moves, and cause diarrhoea.
  2. When FODMAPs reach the large intestine they are fermented by the bacteria that naturally live there and just like when beer is fermented, this process creates gas and bubbles. For the individual this results in abdominal distention, bloating and cramping.

IBS, does not cause physical damage or lead to long term complications. The goal of treatment is to manage symptoms, meaning that high FODMAP foods only need to be restricted as far the symptoms dictate.


Fermentable Molecules resist digestion, pass through the digestive tract to the colon where they are fermented, creating IBS symptoms.


“oligo” means “few” and “saccharide” means sugar. These molecules made up of individual sugars joined together in a chain. Include Fructans & Galactans found in onion, garlic, wheat, barley, rye, inulin, some dried fruit and Legumes (kidney beans, lentils, chickpeas, soy beans).


“di” means two. This is a double sugar molecule. Lactose is the di-saccharide found in milk, yoghurt, some soft cheese’s, ice cream, custard and cream.


“mono” means single. This is a single-sugar molecule.

Fructose in excess of glucose found in asparagus, apples, mango, honey, cherries, some dried fruit, pears, juice and high fructose corn syrup.

And Polyols


Sugar alcohols including Sorbitol & Mannitol found in cauliflower, mushrooms, snow peas, stone fruit and certain artificially sweetened products e.g. mints and gums.


Why the confusion?

graphic of wheat, protein and carbohydrate
The diagram below shows that wheat contains both protein (gluten) and carbohydrates (FODMAPs). Although these are different molecules, they commonly occur in the same products. By removing wheat products from your diet, you actually remove both Gluten and FODMAPs. This means that it can be difficult to say with certainty if eliminating the gluten or the FODMAPs made the difference.


It is also important to note that not all gluten free foods are low FODMAP and not all low FODMAP foods are gluten free. For example, spelt and wheat sourdough, soy sauce and small serves of wheat pasta are considered low FODMAP. Additionally, many gluten free breads contain high FODMAP ingredients like besan flour, soy flour, honey or inulin.


At this point in time the evidence is suggesting that, in the absence of Coeliac Disease, removing the FODMAPs, and not the Gluten, gives the best symptom relief for people who have IBS.


list of high FODMAP foods                     list of low FODMAP foods


Where to from here?

Since there are many serious medical conditions, including Coeliac Disease, that can cause similar symptoms to IBS, it is important to visit your doctor and be tested for these. For tests to give accurate results, this must be done beforecommencing a gluten free diet. If all tests are negative, the next step is to see an Accredited Practising Dietitian to commence a low FODMAP diet.


Since FODMAPs are found in a large variety of foods and across many food groups, it can be tricky to know which foods are high FODMAP and which foods are low FODMAP. Downloading the FODMAP Friendly smartphone app and looking for the registered certification trademark on packaged foods, are the best ways to identify foods that can be eaten with confidence as part of a low FODMAP diet.


Final Thoughts

Being on a gluten free diet can be over restrictive, limit access to certain nutrient’s and is not necessary as part of a low FODMAP diet. It also will not guarantee that you are eating a low FODMAP diet.


Joanna & Marnie are gut health expert dietitians with the knowledge and skills to support you with personalised advice and gut health solutions. We consult privately in Melbourne’s inner south east and via Skype. To make an appointment or seek advice, you can call any of the consulting rooms directly or email us at