fructans and galactans intolerance

Fructans and galactans are long carbohydrate chains of about 3 to 9 carbohydrate molecules. Fructans are also called fructo-oligosaccharides (FOS) and gallactans galacto-oligosaccharides (GOS). Oligosaccharides belong to the non-digestible carbohydrates. These carbohydrates cannot be broken down in the small intestine and leave the body through the large intestine. In the colon, these undigested carbohydrates are fermented, releasing gas and attracting fluid, among other things.

No one can digest fructans and galactans properly, the difference is in the amount of symptoms you get as a result of the fermentation process. Our focus here is of fructan or galactan intolerance when someone suffers greatly from the fermentation process. It can differ from person to person whether someone only reacts to fructans or galactans, or to both types of oligosaccharides.

Fructans and galactans are both oligosaccharides; because they are very similar, our bodies usually treat them the same. The difference between fructans and galactans is in the structure: with fructans there is a bonded fructose molecule attached to the chain, however, with galactans there is a bonded galactose molecule. You can be sensitive to either type of oligosaccharide or both at the same time. It can sometimes be unclear which of the two you react to because many foods contain both fructans and galactans.

Sometimes there is some confusion about the difference between fructans and gluten. Many people think they are reacting to gluten after eating bread or other grain products, however they could in fact, be reacting to fructans. Grain products made from wheat often contain high levels of fructans as well. A gluten-free diet can help because it reduces your intake of fructans.

A gluten allergy, also known as gluten intolerance or celiac disease, is another type of disorder. Due to a reaction of the immune system, the intestinal wall can be damaged after eating products containing gluten. However, if a celiac test comes back negative, then there is a good chance that it is a fructans intolerance.

In the case of fructans intolerance, there is no immune system reaction and no damage to the intestinal wall. Fructans are found in many other products, such as fruits and vegetables, in addition to cereal products.

Check out our detailed explanation of fructans, galactans and the difference with gluten here:

Fructans and galactans occur naturally in many foods, such as vegetables, fruits, legumes and grain products. There are foods that contain only fructans or only galactans and there are foods that contain both.

Foods rich in fructans are:

  • Garlic
  • Onion
  • Leeks
  • Wheat
  • Apricots
  • Grapefruit
  • Nectarine

Foods rich in galactans are:

  • Brown beans
  • Chickpeas
  • Peas

Foods rich in both fructans and galactans:

  • Cashews
  • Pistachios
  • Soybeans
  • Split peas

In addition to the examples above, there are many other foods that contain fructans and/or galactans. In the low FODMAP app from Monash University, you can easily check which foods are safe and which foods you should limit to prevent symptoms.

Symptoms of fructan or galactan intolerance are mainly caused by the fermentation process in the large intestine, where the intestinal bacteria try to break down the fructans and galactans. This process attracts moisture and can also release gas, which can cause unpleasant intestinal symptoms. The most common symptoms associated with fructans or galactans intolerance are:

  • Abdominal pain
  • Bloated stomach
  • Constipation (obstipation)
  • Diarrhoea
  • Intestinal cramps
  • Flatulence

Are you unsure whether you have a gluten allergy (celiac disease) or a fructan intolerance? If so, contact a doctor or dietitian. If a blood test shows that you do not have celiac disease, then you can start to find out if fructans are causing your symptoms.

Most people continue to suffer from their fructan or galactan intolerance for the rest of their lives. Fortunately, it is easy to live with, as long as you know what things to take into consideration to prevent symptoms as much as possible.

If you know whether you are sensitive to fructans, galactans or both, you can adjust your diet. By limiting foods rich in fructans and/or galactans you can also limit the fermentation process and prevent symptoms. Exactly which foods cause a reaction may be different for each person. For example, some people only react to fructans from wheat, while others can tolerate wheat perfectly but are sensitive to onion and garlic.

Finding out which foods you react to can be a long, in depth process, but in time you will learn to know your body and you will know which foods you can tolerate and which you should avoid. It is beneficial to find out how much your body can tolerate. Most people can tolerate a small amount of fructans or galactans in their food, while for others this small amount can cause unpleasant symptoms. A dietitian can help people with fructan or galactan intolerance become reaquainted with trigger foods and provide advice for a balanced diet.

Our bodies normally don’t produce an enzyme in the small intestine that can break down fructans and galactans. As a result, they end up in the large intestine where they are fermented. When this fermentation process causes symptoms, such as with fructans or galactans intolerance, taking supplements with enzymes may be a good option.

Certain enzymes, such as the enzyme Alpha Galactosidase, have the ability to break down oligosaccharides such as fructans and galactans. The smaller carbohydrate molecules created in the process can be properly digested. If you take this enzyme in supplement form with your meals, you can digest the fructans and galactans better. If you have questions about these supplements it is advisable to consult a dietitian.

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