Articles on: Challenges/Discovery Plan

FODMAPs: FOS, GOS & Mannitol


You may have noticed in the FoodMarble app that we offer direct testing for Lactose, Fructose, Sorbitol and Inulin, but there are other FODMAPs that can cause fermentation. FOS (Fructans), GOS (Galacto-oligosaccharides) and Mannitol are all FODMAPs that you should be aware of. In our food library, you can search for foods that include these FODMAPs using the filters.

While we currently don’t provide testing packets for these FODMAPs, it is still possible to test your response to them. You can complete a custom challenge and test for the FODMAP through foods they appear in.

In this article we’ll explore how to do this and what kinds of insights it can provide to our diets.

Understanding FOS, GOS and Mannitol

FOS (Fructans): FOS are a type of fermentable carbohydrate found in a variety of foods, including wheat, onions, garlic, and certain fruits. Some individuals are intolerant to FOS, experiencing digestive symptoms such as bloating and discomfort after consumption.

GOS (Galacto-oligosaccharides): GOS are another group of fermentable carbohydrates found in foods like beans, lentils, and certain grains. People with GOS intolerance may experience gas, bloating, and other digestive issues.

Mannitol: Mannitol is a sugar alcohol found naturally in some fruits and vegetables, as well as in sugar-free gum and other artificial sweeteners. Mannitol intolerance can lead to symptoms like diarrhea and abdominal pain.

We lack the necessary enzymes to break down these long chains of fructose. Remember, the longer chains of fructose are known as inulin (more than 10) and the shorter chains of fructose are known as FOS (2-9 fructose molecules). We are not able to digest fructans in the small intestine. This means they travel along to the large intestine, where our gut microbes break them down for us. The bacteria in our gut have the necessary enzymes to ferment these undigested sugars. As they are broken down, gases (like hydrogen) and other important fermentation products (like short-chain fatty acids – SCFAs) are produced.

Testing for FOS, GOS and Mannitol

To test for additional FODMAPs or to test a specific food you can complete a custom challenge. This can help with confirming if you have an intolerance to any 3 of these FODMAPs as well as finding your unique threshold before you begin to experience symptoms. In most cases - we can eat a certain level of FODMAPs before they begin to affect our digestive system and finding that threshold is the key. We have a helpful article on custom challenges and recommendations for testing these FODMAPs.

Updated on: 26/02/2024

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