What are FODMAP and how do they affect IBS?

IBS and dietary advice

IBS problems have for a long time 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. 

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? 

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, 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. 

What is FODMAP?

FODMAPs (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 an important role, even if IBS patients may experience problems with the increased gas formation, among other things, especially if the diet is excessively rich in FODMAPs.

Different FODMAPs

FODMAPs are made up of several different groups of fermentable carbohydrates. 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

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

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 balance the intake of fructose with other foods containing glucose to reduce the amount of fructose that remains in the intestine. 

Polyols or sugar alcohols

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 much FODMAPs we can handle. If you know that you have a high intake of the foods above, such as onions, garlic, apple juice, watermelon, canned fruit, and honey, you can try to reduce these a bit.

A so-called FODMAP diet, where you completely replace different foods, however, should never be tried on your own without the support of a dietitian or a doctor. 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. 

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 miss out on important nutrients, but in addition to this, some worrying negative effects have been seen on the composition of the intestinal flora after a long-term FODMAP diet, which could increase the risk of significantly more serious diseases in the long run.