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The beginner's guide to the low FODMAP diet

Der Anfänger Ratgeber zur Low-FODMAP Ernährung

If you're like most people, you've heard about the 'dangers' of gluten but have no idea what a FODMAP is.

And if you regularly suffer from digestive discomfort such as bloating, a bloated feeling, abdominal pain, cramps, heartburn, fatigue, diarrhea or constipation after eating something, then you should definitely read this article.

In this case, reducing your FODMAP intake is probably something that will solve your problems better than a gluten-free diet.

In fact, scientific research has found that a low-FODMAP diet relieves symptoms in 74% of IBS patients and FODMAPs are the real culprit in what many people consider to be an unrelated gluten intolerance (1, 2).

So let's take a look at what FODMAPs are, why they can be so problematic and how you can assess your sensitivity to FODMAPs and eliminate them from your diet if necessary.

What is a FODMAP?

FODMAP stands for fermentable oligosaccharides, disaccharides, monosaccharides and polyols. These are the scientific terms for a type of carbohydrate that is difficult to digest and can be found in plant-based foods, dairy products and sweeteners. For the sake of simplicity, let's look at this acronym word by word.

It starts with fermentable because these carbohydrates are easily fermented in the gut. This is followed by three types of saccharides, which are sugar molecules found in food.

Monosaccharides are often referred to as simple sugars because they have a very simple structure and consist of only one sugar molecule. Mono means one and saccharide means sugar - i.e. one sugar.

Monosaccharides include...


Glucose is a type of sugar also known as blood sugar. Glucose is found in the blood and is produced from the food you eat (most carbohydrates in food contain glucose - either as simple glucose molecules or combined with the two other simple sugars we'll see in a moment).

When we talk about blood glucose levels, we are referring to the amount of glucose circulating in the blood.


Fructose is a type of sugar that occurs naturally in fruit and is also found in processed products such as sucrose (table sugar) and high fructose corn syrup, both of which are 50% fructose and 50% glucose.

Fructose is converted into glucose in the liver and then released into the bloodstream, and can also be converted into fat at higher intakes and contribute to non-alcoholic fatty liver disease.


Galactose is a type of sugar found in dairy products and is metabolized in a similar way to fructose.


Oligosaccharides are molecules that contain several monosaccharides linked together in chain-like structures. Oligos is the Greek word for "united" - oligosaccharides therefore means "some sugars".

These sugars are one of the components of fiber in plants, which our bodies can partially break down into glucose (leaving the fibrous indigestible parts behind to do good things in our digestion) (3).

Many vegetables contain fructo-oligosaccharides - short chains of fructose molecules. These are metabolized in the same way (the chains are broken down into individual fructose molecules, which are then converted into glucose for further use by the body).

Another common form of oligosaccharide in the diet is raffinose, which consists of a chain of galactose, glucose and fructose (also known as a trisaccharide) and is found in beans, cabbage, broccoli, Brussels sprouts, asparagus, other vegetables and cereals. Galactooligosaccharides round off the list of oligosaccharides and consist of short chains of galactose molecules. They are indigestible but play a role in stimulating the growth of healthy gut bacteria (4).


Disaccharides are molecules that are composed of two monosaccharides.

Two common examples of disaccharides are milk sugar (lactose), which consists of glucose and galactose, and table sugar (sucrose), which consists of glucose and fructose.


Last but not least, there are the polyols, which are also known as sugar alcohols. Polyols are a group of low-calorie, sweet carbohydrates that can be used as a substitute for table sugar.

The most popular polyols are erythritol, maltitol, xylitol (xylitol) and sorbitol.

If you look at the list of all these foods I have just listed, you will understand why people with FODMAP hypersensitivity often struggle with their condition.

It goes far beyond wheat and wheat products, which are the dietary scapegoat of the day.

FODMAPs are ubiquitous in the modern Western diet and people with a FODMAP sensitivity can work hard to maintain an extremely "clean" diet rich in fruits, vegetables, legumes and the like...only to suffer anyway.

They would never suspect that the problem is that their body simply cannot properly digest and absorb all these "healthy" foods they are eating (5). For example, foods that are most likely to light up the FODMAP warning lights include

  • apples
  • asparagus
  • turnips
  • broccoli
  • Brussels sprouts
  • Cabbage
  • Chicory
  • Chickpeas
  • Legumes
  • Mushrooms
  • Onions
  • Peaches
  • Pears
  • Radicchio
  • Watermelon
  • Processed grains and cereals

FODMAPs are also found in inconspicuously harmless spices, canned foods and soft drinks such as fruit juice and many other foods.

Scientific research has shown that some people only experience reactions when they consume certain amounts of FODMAPs, making it even harder to understand the circumstances (6).

Why are some people sensitive to FODMAPs?

In the case of oligosaccharides, humans simply lack the enzymes necessary to break them down (7). This means that when these carbohydrates reach the gut, they are still relatively intact, which can lead to digestive discomfort.

The two main culprits here are fructans and galactans.

Fructans are a form of fructose found in various fruits and vegetables, legumes and grains, while galactans are a form of galactose found mainly in legumes.

In the case of disaccharides, the most problematic by far is lactose (a sugar found in mammalian milk). Although the body is capable of producing an enzyme called lactase that can break down lactose, many adults are no longer able to do so, which has led to the widespread development of lactose intolerance.

Of the monosaccharides, fructose is the one that causes the most problems. Once it reaches the intestines, it can draw water and cause swelling of the intestines, which sends a signal to the nervous system that something is wrong.

Scientific research shows that this can happen even in healthy, symptom-free people (8).

If a large dose of fructose is consumed on its own (e.g. 50 grams), then the majority of people will not absorb at least some of it properly, which can lead to symptoms normally associated with fructose hypersensitivity.

(This highlights one of the problems with the widespread use of high fructose corn syrup in some countries such as the USA).

Polyols, which are found in many sugar-free foods, sweets and chewing gums, are only partially digested and absorbed in the small intestine and once they reach the large intestine they can cause bloating and have a laxative effect.

Who should avoid FODMAPs?

If you suffer from any of the following problems, a diet low in FODMAPs could help reduce your symptoms.

  • Digestive problems
  • Lactose/fructose malabsorption
  • Inflammatory bowel disease (Crohn's disease, ulcerative colitis)
  • Irritable bowel syndrome
  • Suspected non-celiac disease due to gluten intolerance

Many of these disorders reduce quality of life and do not respond well to medication, which is why alternative treatment approaches are often welcome.

How do you know if you suffer from FODMAP hypersensitivity?

Although simple breath tests claim to be able to detect FODMAP hypersensitivity (with questionable accuracy), they can only test for some of the potential culprits (fructose, sorbitol and lactose).

The most reliable way to assess your gut's relationship to FODMAPs is through a comprehensive elimination diet.

An elimination diet is a strategic approach to reducing and reintroducing FODMAPs into your diet and carefully monitoring your body to learn how each food affects you.

A typical FODMAPs elimination diet lasts 6 to 8 weeks and looks like this:

First, you reduce your overall intake of FODMAPs

You can do this by replacing foods that are rich in FODMAPs with options that are lower in FODMAPs, or by reducing the total FODMAPs load per meal.

This phase should be at least 4 weeks long - or until your symptoms are under control.

Next, systematically reintroduce FODMAPs into your diet

Here you start by reintroducing one FODMAP at a time into your diet, paying careful attention to how your body reacts.

A detailed food and symptom log is the only way to get an overview of what is causing your problems - attention and patience are key here.

Last but not least, modify and expand your diet

The final step is to work on gradually expanding your diet to include FODMAPs in tolerable amounts.

You may well find that only one or two foods are responsible for most of your symptoms and some people find that they can continue to eat their favorite foods in moderation.

If that sounds like a lot of effort, then I can understand. However, you should remember that this is a one-time thing that will help you find the optimal FODMAP levels for your body.

The goal isn't to completely change your diet - it's to find a varied eating plan that suits your needs and produces the least amount of symptoms.

How to eat a diet low in FODMAPs

A low FODMAP diet focuses on foods that are low in gluten, dairy and fructose and avoids fruits and vegetables that contain rapidly fermentable soluble fiber.

There are sites and apps on the internet that contain comprehensive lists of low FODMAP foods.

More and more dietitians and doctors are starting to recommend low FODMAP diets for diagnostic and therapeutic purposes, so you can get support from this side too.

And if you're worried that a low-FODMAP diet won't leave you with anything good to eat, don't worry.

Here is a list of my favorite low-FODMAP foods:

  • Fruit: bananas, oranges, tangerines, grapes, melons.
  • Grain products: Gluten-free bread and sourdough spelt bread, rice cakes, oatmeal, gluten-free pasta, rice, quinoa
  • Dairy products: Lactose-free milk, lactose-free yogurt, virtually all types of hard cheese.
  • Nuts/seeds: Almonds ( - Protein: meat, fish, poultry, tofu, tempeh.
  • Vegetables: alfalfa, mung bean sprouts, green beans, bok choy, peppers, carrots, fresh herbs, cucumber, lettuce, tomatoes, zucchini, leeks
  • Other snacks: gluten-free cookies, rice crackers You can make it easier for yourself by creating a personalized list with your FODMAP preferences in mind.

It's also a good idea to prepare your own meals and snacks to keep an eye on the exact ingredients. Remember that FODMAPs lurk in many unexpected places.

Finally, once you have found the FODMAPs you are most sensitive to, you can start using digestive enzyme supplements that aim to break down these FODMAPs. This targeted approach to enzyme supplementation can significantly reduce your symptoms (9).

It's also worth noting that many foods that are rich in FODMAPs are also highly nutritious. This is one of the reasons why it may not make sense to follow a low-FODMAP diet forever - even if you are sensitive to these foods.

The goal is not to banish FODMAPs from your life - it's to find the happy medium for your body between complete FODMAP overload and strict abstinence, where the diet is balanced but your symptoms are almost eliminated.

The bottom line on the low-FODMAP diet

Unlike the many fad diets that come and go, the low-FODMAP diet is a legitimate, science-based strategy for improving your digestive health and long-term well-being.

If you don't generally suffer from digestive problems after eating, then there is no need for such an approach.

However, if you do suffer from such issues - and especially if you think you suffer from gluten hypersensitivity - a low-FODMAP lifestyle could change everything.




By Michael Matthews

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