Fructooligosaccharides (FOS) are a form of carbohydrate. While they may be generally considered safe to use, they may also cause certain side effects. These include cramps, nausea, and bloating. FOS may also provide benefits, such as lowering blood sugar and cholesterol.

The term saccharide is another word for sugar, and an oligosaccharide is a molecule made up of a small group of these sugars.

Fructooligosaccharides are used as alternative sweeteners because they carry less calories than sugar; they do not cause a spike in blood sugar.

Although there are some potential benefits associated with using fructooligosaccharides, there may also be some risks and side effects. In this article, we will look at both the risks and benefits.

Fast facts on fructooligosaccharides:

  • Fructooligosaccharides are forms of oligosaccharides and come from natural sources.
  • Their sweet flavor makes them a common choice for alternative sweeteners.
  • Overusing fructooligosaccharides can cause side effects, including digestive upset and abdominal stress.
  • In general, the best way to add them to the diet is by eating a varied diet rich in the whole foods that contain them.
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Fructooligosaccharide itself can be a mouthful to say, and it may help to break it down.

It can be pronounced as frook-tahl-ih-go-sack-uh-ride, with the emphasis usually on “tahl.” Luckily, it is often referred to as FOS.

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An example of a FOS containing food turned into a powder, is chicory root.

The potential side effects of using FOS include:

Some people may be more sensitive to the effects of FOS. In these people, side effects may be felt even after using a small amount of FOS. Allergic reactions may include:

  • itching in the throat
  • puffiness in the eyes, face, and mouth
  • dizziness, lightheadedness, and fainting
  • hives, itching, and eczema

Severe allergic reactions may cause anaphylactic shock, which is a potentially fatal response. Any signs of allergic reaction are a cause to contact a doctor.

People with digestive disorders such as irritable bowel syndrome (IBS) may want to avoid using FOS, as their digestive system may not respond well to the effects. There is little current research, however, on this topic.

Since FOS feed bacteria, there is also the chance that they can feed unfriendly bacteria in the gut. Certain organisms, including E. Coli and K. Pneumonia, may eat FOS and spread in the intestines. This may be more likely if they are weakened.

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FOS may be recommended as an alternative sweetener.

As a dietary ingredient, FOS fits into a few different categories. It is a carbohydrate but is usually listed under fibers. It is also used as a sweetener.

An interesting note about FOS is that it passes through the intestines undigested.

FOS does not cause a spike in a person’s blood sugar as other sweeteners do, and it is also low in calories. For these reasons, FOS may be ideal for people looking for an alternative sweetener.

While FOS is commonly added to beverages, syrups, and foods, as a sweetener, there are also many benefits of consuming FOS including:


Complex FOS are considered prebiotics. Not to be confused with probiotics, a prebiotic helps feed the good bacteria in the intestine.

FOS are often used in baby formula to help feed the beneficial bacteria that the intestines need.

Source of soluble fiber

Soluble fiber helps to absorb water in the intestines and give the fecal matter a consistent shape. Increasing the levels of soluble fiber in the diet from FOS has been shown to reduce or eliminate digestive issues, such as constipation or diarrhea. This regulatory effect may also be caused in part by FOS feeding the good bacteria in the colon.

Lowers cholesterol

A recent review in Acta Cirurgica Brasileira found that FOS can reduce cholesterol levels in animal studies. Introducing FOS into a calorie-restricted diet also helped these animals to reduce weight gain.

The researchers noted the likelihood that FOS supplementation is good for lowering cholesterol in humans, as well.

Reduces blood sugar

FOS may also be great news for people with diabetes. A review in the journal Nutrients noted the potential ability of FOS to help balance a person’s blood sugar. The researchers observed a positive correlation between FOS intake and decreasing serum glucose levels.

FOS usage also seemed to stimulate insulin secretion in the pancreas. More human studies will be needed to substantiate these findings.

Does not feed cancer cells

While there is debate surrounding the safety of using sweeteners, FOS may be left out of the mix in some cases. FOS is not carcinogenic, and it has little potential to disrupt or damage normal cell growth. Consuming FOS will not feed cancer cells or contribute to their growth.

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FOS naturally occurs in onions and garlic.

In nature, FOS is found in many different plants, including common plants such as:

  • banana
  • artichoke
  • onion
  • chicory
  • garlic
  • asparagus
  • yacon root
  • blue agave

FOS is found in many other plant species in nature, as well.

FOS is broken down in various ways, and this results in different end products that have different uses and varying benefits. FOS comes in a few different forms, and each may be used for a specific purpose.


Some types of FOS are broken down and made into syrup. Common examples include yacon root syrup and blue agave syrup. These can be diluted in water and taken as a supplement or can be added full strength to recipes or added to food and drinks, as a sweetener.


Chicory root is the most common example of a FOS-containing food turned into a powder. Ground chicory root is commonly used as a coffee alternative. Mixing a spoonful into warm water provides a similar taste to coffee without as much stimulation.


Many other types of FOS are made into extracts of varying strength or concentration. These may come from a whole food source, such as artichoke or chicory. They may also be made through a chemical process rather than through a natural one, possibly leaving them less beneficial.

The debate about the use of sugar and other sweeteners is ongoing.

According to research in the Journal of Pharmacology & Pharmacotherapeutics, sweeteners, such as sugar and high-fructose corn syrup, have been linked to increased risk of disorders that include obesity and dental problems. Some controversial theories suggest sugar also plays a role in some degenerative diseases.

Alternative sweeteners duplicate the effects of sugar without many of the calories so, in theory, they should be healthy.

The chemical makeup of many alternative sweeteners is different, and studies have just begun to scratch the surface on their possible health benefits or side effects. A number of studies have been done on these sweeteners, with varying results. Some say they are harmless, while others say they should be completely avoided.

While FOS may provide some people with a beneficial sweetener or an easy form of prebiotic to improve their gut health, it might not be wise to overeat these extracts. Consuming a diet rich in the foods containing FOS may be the best way to enjoy the benefits without ingesting an excess.