Demystifying FODMAP and Gluten

It has been long believed that if you follow a low FODMAP diet then you will also be eating gluten-free. Unfortunately, this is misinformation. 

Each diet eliminates components of foods that contain both FODMAPS and gluten. The FODMAP diet is designed to begin by eliminating high FODMAP containing foods: fermentable sugars; oligosaccharides (fructans, galacto-oligosaccharides), disaccharides (lactose and milk sugar), monosaccharides (excess fructose), and polyols (sugar alcohols). Gluten-free eliminates all gluten containing foods. 

The common denominator are the food sources; wheat, barley, and rye, which contain both fructan and gluten.

What are those again?......

Fructan, specifically, is the oligosaccharide found in many foods that contain wheat, barley, and rye. They are a type of carbohydrate, fermented in the large intestine, containing long chains of fructose joined together and can cause digestive discomfort (gas, bloating, diarrhea, constipation, and pain). 

Gluten is a naturally occurring protein found in wheat, barley and rye. It is used to add protein, texture, and flavor and is also used as a binding agent to hold processed foods together and give them shape. A gluten-free diet is therapeutic for people who suffer from the autoimmune disease known as celiac disease. This is where the immune system triggers an inflammatory reaction and damages the lining of the small intestine. 

Back to the diets…..

Things get tricky because there are some low FODMAP foods that still contain gluten. Inversely, you can follow a gluten-free diet and still be consuming high FODMAP foods. Generally speaking, gluten and FODMAPs are often found in the same foods (wheat, barley, rye; mainly oligosaccharides), except when they are not.

There are multiple studies that displayed a reduction of gastrointestinal symptoms in both celiac disease-specific and non-celiac disease specific patients who have followed the low FODMAP diet (CGH, 2022; BMC Gastroenterol, 2021). One double-blind, placebo controlled randomized clinical study concluded that fructan vs. gluten exacerbated symptoms in most of the IBS patients in the study (Clin Nutr ESPEN, 2022).

If you do not suffer from Celiac disease, but you do suffer from IBS/IBD then following a low FODMAP diet is the more beneficial way to go. Since the FODMAP diet is already eliminating many nutrient sources you do not want to unnecessarily exclude other food sources. Doing so can lead to serious nutrient deficiencies that could otherwise be avoided once you are in the challenge/reintroduction phase of FODMAP.

The following list are foods that contain gluten, but are low FODMAP:

  • Sourdough bread (spelt or wheat)
  • Soy sauce (2 tbsp)
  • Low FODMAP products with tiny amounts of gluten (such as yeast spread Vegemite, which was named in this article).
  • Additionally, it is always best to consult with a registered dietitian or Monash FODMAP trained registered dietitian to help you navigate the different phases of the low FODMAP diet to ensure you are completing the elimination and challenge/reintroduction phase appropriately.

In contrast here is a list of high FODMAP foods that are gluten-free:

  • Flours: Chickpea, Coconut, Soy
  • Sweeteners: Agave Syrup, Honey, Molasses
  • Inulin & chicory root
  • Dried fruits such as dates and mango
  • Various fresh fruit and vegetables including cherries, garlic, artichoke.
  • Various legumes at medium-high serving sizes (see here)

Having to deal with the discomfort that comes along with any IBS/IBD related disease is already really tough. Learning you need to be restrictive with dieting in an effort to have a better quality of life can get confusing. There is no need to be overly restrictive if you are not suffering from celiac disease, especially when there is growing evidence to support low FODMAP for symptom relief. 

If you are concerned you may have celiac disease it is important to see your provider and get tested. (*starting a gluten-free diet prior to testing can impact accuracy with diagnosis and should be avoided)

Biesiekierski JR, Peters SL, Newnham ED, Rosella O, Muir JG, Gibson PR. No Effects of Gluten in Patients With Self-Reported Non-Celiac Gluten Sensitivity After Dietary Reduction of Fermentable, Poorly Absorbed, Short-Chain Carbohydrates. Gastroenterology. 2013;145(2):320-8.e3.

Mohseni F, Agah S, Ebrahimi-Daryani N, Taher M, Nattagh-Eshtivani E, Karimi S, Rastgoo S, Bourbour F, Hekmatdoost A. The effect of low FODMAP diet with and without gluten on irritable bowel syndrome: A double blind, placebo controlled randomized clinical trial. Clin Nutr ESPEN. 2022 Feb;47:45-50. doi: 10.1016/j.clnesp.2021.12.019.

Naseri, K., Dabiri, H., Rostami-Nejad, M. et al. Influence of low FODMAP-gluten free diet on gut microbiota alterations and symptom severity in Iranian patients with irritable bowel syndrome. BMC Gastroenterol 21, 292 (2021). https://doi.org/10.1186/s12876-021-01868-5

Nordin E, Brunius C, Landberg R, Hellström PM. FODMAPs, but not gluten, elicit modest symptoms of irritable bowel syndrome: a double-blind, placebo-controlled, randomized three-way crossover trial. The American Journal of Clinical Nutrition. 2021.

Skodje GI, Sarna VK, Minelle IH, Rolfsen KL, Muir JG, Gibson PR, et al. Fructan, Rather Than Gluten, Induces Symptoms in Patients With Self-Reported Non-Celiac Gluten Sensitivity. Gastroenterology. 2018;154(3):529-39.e2.

van Megen F, Skodje GI, Lergenmuller S, Zühlke S, Aabakken L, Veierød MB, Henriksen C, Lundin KEA. A Low FODMAP Diet Reduces Symptoms in Treated Celiac Patients With Ongoing Symptoms-A Randomized Controlled Trial. Clin Gastroenterol Hepatol. 2022 Jan 17:S1542-3565(22)00034-9. doi: 10.1016/j.cgh.2022.01.011. 

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