FODMAP diet: what is it and how does it affect the digestive tract


About 15-20% of adults are familiar with irritable bowel syndrome (IBS) today, and athletes are no exception. Approximately one in 7 bodybuilders will show symptoms typical of this pathology – bloating, rumbling, discomfort or wandering pain in the intestines, flatulence, and stool disorder. What is the root cause of this syndrome, scientists have not yet figured out, but at the Australian Monash University, Susan Shepherd and Peter Gibson have developed a system of eating behavior that helps with this pathology. It’s called the FODMAP diet.

What is a FODMAP diet?

FODMAP is an abbreviation for:

  • F – FERMENTABLE – the process of fermentation (digestion) by the microbiota of the large intestine of sugars, which, due to their short-chain structure, are not absorbed in the small intestine. The group of such carbohydrates includes the saccharides and sugar alcohols listed below.
  • O – OLIGOSACCHARIDES – oligosaccharides – galactooligosaccharides and fructans.
  • D – DISACCHARIDES – maltose and lactose.
  • M – MONOSACCHARIDES – fructose.
  • A – and – preposition “and”.
  • P – POLYOLS – polyols – sorbitol, mannitol, xylitol, maltitol, erythritol.

All these saccharides and sugar alcohols belong to the class of short-chain carbohydrates. When they enter the small intestine, they move slowly through it, attracting and capturing water molecules. When they are digested by the microbiota of the large intestine, water is released.

And a large amount of gas and substances that irritate the intestinal walls are released. Gases and H2O molecules cause the walls of the lower sections of the large intestine to stretch. All this together causes rumbling, discomfort, pain, diarrhea/constipation, or alternating solid and liquid stools in one bowel movement.

The FODMAP diet is a personalized diet that eliminates those types of carbohydrates that cause symptoms of IBS in a particular person. To create such a diet, you first need to give up meals, nutritional supplements, and foods with a large amount of FODMAP for 0.5-1.5 months. After the persistent disappearance of the symptoms of IBS, you need to include them in the menu one at a time, and evaluate the response of the microbiota within 3 days.

Attention! If after 2-6 weeks of complete rejection of all foods, meals and nutritional supplements with a high content of FODMAP, the signs of IBS have not disappeared, a mandatory consultation with a gastroenterologist is necessary. Similar symptoms are also characteristic of chronic pathologies of the liver, gallbladder, pancreas, intestinal diseases, and gluten intolerance.

Additional Recommendations

Below is more information about the FODMAP diet from Monash University.

How effective is the FODMAP diet?

This diet has been shown to help 3 out of 4 IBS patients. Those to whom it did not help are recommended to try it again after 3-4 months, paying special attention to the following points:

  1. Then make sure that the fiber content in the daily diet is in the range of 25-38 g. Fill in the missing part with prebiotic fiber with low FODMAP content. If it is not possible to buy such a special supplement, then a similar combination can be made independently, for example, by purchasing a supplement with guarana, checking that it does not contain components related to short-chain carbohydrates, and a prebiotic complex containing Bifidobacteria and Lachnospiraceae.
  2. Avoid supplements that contain ingredients such as:
  • inulin
  • GOS
  • wheat dextrin
  • IMO

Before starting a diet, take appropriate tests, and then maintain normal levels of sugar (insulin) and cholesterol in the blood. To do this, when compiling a daily menu, you need to take into account the glycemic index of foods, the amount of simple fast carbohydrates eaten at one meal, as well as the number of foods and dishes with animals or combined fats.

To keep a diary. It is possible that bowel problems and stool disorders are the consequences of stress, lack of sleep/rest, taking hormonal drugs, or hormonal imbalance due to illness.

The authors of the diet also point out that some low FODMAP foods “move” into the high FODMAP category if you eat them in large portions.

Does Cooking Technique Affect FODMAP Concentration and Digestion?

Yes, it does. It has been proven that fermenting and preserving vegetables and fruits in an acidic medium (vinegar) leaches the short-chain carbohydrates contained in them into the brine. Therefore, the liquid must be drained and not used, and pickled or canned vegetables/fruits/berries should be washed in running water.

There is also evidence that very high temperatures can also destroy FODMAP. Studies on this subject are underway, and their results will be published in the form of tables.

How can garlic and onion be used?

The amount of short-chain carbohydrates in garlic and onions is too high, and pickling or preserving them with vinegar still does not allow them to be included in the FODMAP diet menu. However, you can enrich the taste of dishes with these spices. To do this, fry them in vegetable oil for 1-2 minutes, and then strain it and use it for dressing, making sauces, and gravy.

Low FODMAP Fruits Still Causing Gut Signs: What to Do?

Avoid large portions of any fruit and berries, even if they are on the low FODMAP list. Moreover, do not use them in dried or dried form, as in the process of removing moisture from them, some simple sugars are converted into poorly absorbed short-chain fructans.

Does sourdough bread improve digestion?

Indeed, the level of fructans in sourdough bread is lower, as they are used by yeast bacteria and lactobacilli during the fermentation process. This allows you to bake and eat bread from flour ground from spelt or oats. Wheat or rye sourdough bread still remains on the list with a lot of FODMAPs.

What is the best way to eat – rarely, but a lot, or often and in small portions?

In the WHO nutritional recommendations, for problems with the gastrointestinal tract, the total daily calorie intake should be divided into 5-7 servings, approximately equal in volume and number of calories.

Is there FODMAP in fats and oils?

There are no carbohydrates in vegetable oils, which means there is no FODMAP. However, some fats and oils do affect intestinal motility and, when consumed in excess, can also cause signs of IBS in some people. In addition to the general initial ban on butter, experts recommend limiting the consumption of oils high in saturated fats – palm oil and coconut oil.

Is meat high or low in FODMAP?

Animal protein sources such as meat, chicken, fish, and eggs are generally FODMAP-free because they have very little or no carbohydrates. However, beware of potential high FODMAP ingredients that are added when preparing or eating these foods. These are breadcrumbs, batter, marinades, sauces, and gravies that contain flour, onions, and garlic.

What can improve FODMAP absorption?

It is worth trying drops or tablets with the lactase enzyme with lactose malabsorption. The enzyme “alpha-galactosidase” can aid in the digestion of foods high in galactooligosaccharides (GOS). It may be especially beneficial for vegetarians and vegans who rely on legumes as a key source of protein.

How much sucrose (table sugar) can you eat on a FODMAP diet?

Sucrose is made up of equal parts glucose and fructose. Sucrose is broken down and effectively absorbed in the small intestine. Small amounts, such as 1 to 2 teaspoons in a hot drink or a small handful of candy, are usually well tolerated. However, some people with IBS may not tolerate large amounts of sugar because fructose is a low-chain carbohydrate called a monosaccharide.


The main goal of the FODMAP diet program is the opportunity for an individual to make a reasonable choice of products that do not allow the onset of signs of IBS. However, if such a diet did not give positive results, then it is not worth delaying a visit to the doctor. It is necessary to find out and eliminate the root cause of such a deterioration in well-being so that nothing interferes with bodybuilding, fitness, or other types of physical activity.

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