What are FODMAP and how do they affect IBS?

Jan 21, 2021 | Treatment

Our food gives us water, minerals, vitamins, trace elements, fats, proteins and carbohydrates, etc. We need all of these to function normally, but of course in a well-balanced amount. We also all have different needs and conditions. Factors such as taste, body weight, gender, appetite, exercise habits, education, family relationships, occupation, health, genes, etc. affect what and how we eat. General dietary advice in magazines or found online is therefore not something that usually works long term. In recent years, so-called FODMAP (or more correctly low-FODMAP) diets have appeared in the media and FODMAPs in the diet have been pointed out as possible culprits when it comes to causing problems with IBS (irritable bowel syndrome) such as gas and diarrhea. But what are FODMAPs? In this article, we explain what FODMAPs are and what may be important to know when it comes to so-called FODMAP diets (low-FODMAP diets).

IBS and dietary advice

IBS problems have since long been more or less successfully treated with various dietary advice. It is common for patients who have been diagnosed with IBS by their doctor to also receive a referral or recommendation to see a dietitian to review their diet. By starting from each person’s dietary habits, the dietitian can suggest certain adjustments to the diet that are thought to work to reduce the discomfort from, for example, gas, constipation, diarrhea, etc. Common recommendations are regarding fiber intake or to avoid or reduce certain specific foods or food ingredients. Recently, FODMAPs have been singled out as possible culprits and often presented as a “quick fix” for IBS problems. There are even those who sell FODMAP food and FODMAP advice or FODMAP diets of various kinds. But does the FODMAP diet work? Following a FODMAP diet does not cure IBS, but it may help those who currently have a high intake of FODMAPs in their diet.

Carbohydrates: an important part of our diet

Carbohydrates in the diet can come in various forms. The simplest carbohydrates are called simple sugars or monosaccharides and these include, for example, glucose and fructose. Two monosaccharides can together form a so-called disaccharide, these include ordinary table sugar (sucrose) and lactose. More than two monosaccharides can also form long chains of more complex sugars that can also be branched. These are called polysaccharides (for example starch and cellulose). Mono- and disaccharides taste sweet and are easily absorbed by the body as energy (fast carbohydrates), while polysaccharides do not give a sweet taste and are absorbed more slowly or not absorbed at all, but pass all the way through the gastrointestinal tract (for example so-called fibers).

Both simple and complex sugars are very important to us. They give us energy and a well-functioning gastrointestinal tract. However, it is about balance, and both too much and too little carbohydrates can give us problems. However, our modern diet is usually rich in carbohydrates and the problems of overconsumption are most common with, for example, obesity as a result.

What is FODMAP?

FODMAP (Fermentable Oligo-saccharides, Di-saccharides, Mono-saccharides And Polyols) are carbohydrates with short sugar chains that are not so easily absorbed by our intestines. Instead, these can increase the fluid excretion into the intestine and bacteria (which can of course be bought as probiotics) can use FODMAPs as an energy source through fermentation (a fermentation process). During fermentation, short fatty acids and gases are formed. The effects of FODMAPs are natural and occur in all people and probably have a function in themselves, even if IBS patients may experience problems with, among other things, the increased gas formation, not least if the diet is excessively rich in FODMAPs.

Even though almost every Swedish family sits down and eats tacos and chips on Friday nights, our eating habits differ, not least between different cultures and different countries. In Australia, the intake of FODMAP has generally been shown to be high and it has also been possible to show that people who reduce their intake of FODMAPs have had reduced problems with their IBS.

Different FODMAP

FODMAPs are made up of several different groups of fermentable carbohydrates. We humans cannot break these down because we lack the enzymes required for this. Thus, they remain in the intestines and too much of them can cause discomfort. Disaccharides such as lactose can be a FODMAP but only if enough of the enzyme lactase is missing in relation to the amount ingested. The amount of lactase and thus our tolerance for lactose varies. Monosaccharides can also be FODMAPs if they cannot be taken up to a sufficient extent. Fructose, for example, can be absorbed by the intestine, but transport is dependent on the presence of glucose. It is, therefore, necessary to weigh up the intake of fructose with other foods with glucose to reduce the amount of fructose that remains in the intestine. Polyols or sugar alcohols such as sorbitol and Mannitol are absorbed very slowly and are therefore used as sweeteners in low-calorie products and can cause problems if you ingest too much.

What foods are rich in FODMAPs?

Here is a list of foods that can be rich in FODMAPs. Note that the mentioned foods are rich in FODMAPs in Australia where this research is conducted. Since flavoring and food processing differ, the content of FODMAP in these foods may be different in Sweden.

Oligosaccharides (FOS and GOS) are found in rye and rye products (e.g. rye bread), wheat and wheat products (e.g. wheat bread, pasta, couscous, wheat bran), peaches, persimmons, watermelons, artichokes, and various legumes (bean and lentils), onion, garlic.

The disaccharide lactose is found in milk and yogurt products.

The monosaccharide fructose in excess compared to the amount of glucose is found in cherries, mangoes, canned fruit, watermelon, fruit juices and dried fruit, asparagus, artichokes, sugar peas, honey and corn syrup.

Polyols such as sorbitol are found in apples, pears (apple/pear juice), apricots, pears, nectarines and mannitol are found in cauliflower, mushrooms and watermelon. Sorbitol, mannitol, xylitol isomalt and maltitol are used as sweeteners in sugar-free chewing gums, sweets and chocolate.

How much FODMAP can we tolerate?

We all have a limit to how many of different foods such as FODMAPs we can handle and there are many other reasons to keep a balanced diet. If you know that you have a high intake of the foods above, such as onions, garlic, apple juice, watermelon, canned fruit, honey, etc., you can try to reduce these a bit. ( Here you can download a list of FODMAPs in different foods ).

A so-called FODMAP diet, where you completely replace different foods, however, should never be tried on your own without the support of a professional who is trained in adapting diets. You do not have to go to an expensive consultant privately, and a dietitian at your local health center can certainly help you as an IBS patient with such a diet if you want to try.

However, do not count on a “quick fix” and do not forget that the FODMAP diet is not about excluding FODMAPs forever, but about reducing their excessive intake. Nor is it a diet to be eaten for life, since FODMAPs should be reintroduced back into the diet.

Normalt provas en diet låg på FODMAPs under 6-8 veckor innan man utvärderar effekten. Därefter återintroduceras de FODMAPs man uteslutit till en nivå som kan tolereras.  Detta beror delvis på att man inte vill påverka kostens variation eller näringsinnehåll på sikt men man har även sett vissa oroväckande negativa effekter på tarmflorans sammansättning efter långvarig FODMAP diet. Detta skulle i sin tur kunna öka risken för betydligt svårare sjukdomar på sikt.

Read more about Australian studies at FODMAPs here

University of Gothenburg / SAHLGRENSKA AKADEMIN – Relieved symptoms for IBS patients who avoided difficult-to-digest carbohydrates

Normally, a diet low on FODMAPs is tested for 6-8 weeks before evaluating the effect. The FODMAPs that have been excluded are then reintroduced to a level that can be tolerated. This is partly because you do not want to influence dietary variation or nutritional content in the long run, in addition to this, some worrying negative effects have been seen on the composition of the intestinal flora after a long-term FODMAP diet. This in turn could increase the risk of significantly more serious diseases in the long run.


  • Monash University – & nbsp; Low FODMAP Diet for Irritable Bowel Syndrome
  • J Hum Nutr Diet. 2011 Oct; 24 (5): 487-95.Comparison of symptom response following advice for a diet low in fermentable carbohydrates (FODMAPs) versus standard dietary advice in patients with irritable bowel syndrome.Staudacher HM1, Whelan K, Irving PM, Lomer MC .
  • J Nutr. 2012 Aug; 142 (8): 1510-8. & Nbsp; Fermentable carbohydrate restriction reduces luminal bifidobacteria and gastrointestinal symptoms in patients with irritable bowel syndrome. & Nbsp; Staudacher HM1, Lomer MC, Anderson JL, Barrett JS, Muir JG, Irving PM, Whelan K.
  • J Physiol. 2013 Jan 15; 591 (Pt 2): 401-14. The role of fructose transporters in diseases linked to excessive fructose intake. & Nbsp; Douard V1, Ferraris RP.