Fructooligosaccharides (FOS), a type of carbohydrate found in plants, may be used in various forms as a low calorie sweetener. It’s found in plants like blue agave, chicory root, bananas, and others.

Fructooligosaccharides (FOS) are composed of short fructose chains. They are a type of carbohydrate called oligosaccharides. FOS occur naturally in many plants, which include:

  • blue agave
  • yacon root
  • garlic
  • onion
  • leeks
  • chicory root
  • Jerusalem artichokes
  • asparagus
  • bananas

Fructooligosaccharides are subtly sweet and low-calorie. They are nondigestible, so they don’t have an effect on blood sugar levels. FOS may also have multiple health benefits.

FOS are used primarily as a low-calorie, alternative sweetener. People can eat and drink products made with FOS instead of those containing sugar, which spike glucose levels in the blood, and cause weight gain. FOS may also be preferable to artificial sweeteners, some of which have been linked to everything from weight gain, to diabetes.

FOS can be found in many foods. The highest concentrations are found in:

  • blue agave
  • chicory root
  • garlic
  • onion
  • Jerusalem artichokes

Blue agave is available as a nectar you can dilute in water and drink. You can also use blue agave full strength as a syrup. Chicory root is commonly used as a noncaffeinated substitute beverage for coffee.

FOS are also available in powder form as supplements. They are also an added ingredient in prebiotic supplements in pill or capsule form.

FOS is typically listed on food labels as part of dietary fiber, under the total carbohydrates number. It is an ingredient in some brands of yogurt, nutrition bars, diet sodas, and other products, such as dog and cat food.

Use, or overuse, of FOS may result in abdominal distress for some people. Potential side effects may include:

  • diarrhea
  • gas
  • bloating
  • stomach cramps

FOS may have health benefits that provide value apart from their ability to sweeten food.

They’re prebiotic

Because they are not digestible, FOS travels intact through the small intestine to the colon (large intestine), where they support the growth of healthy bacteria in the digestive tract.

May protect against unhealthy bacteria

As reported in Digestive and Liver Disease, FOS helps suppress Clostridium perfringens, a toxic bacteria associated with food poisoning. One animal study reported in The Journal of Nutrition indicated that FOS may also provide some protection against salmonella, another food-borne illness.

May decrease cholesterol levels

An overview of animal studies indicated that FOS are able to reduce both weight and cholesterol levels in rats and dogs, and that these findings may also be relevant for humans.


According to a review published in Veterinary and Human Toxicology, FOS are not linked to cancer, and are not toxic to humans or animals.

Good source of fiber

FOS are a good source of soluble, dietary fiber. According to a study reported in the journal Nutrients, FOS have been shown to reduce, or eliminate constipation.

There may also be cons to using FOS. These include:

Abdominal distress

According to one study, reported in Gastroenterology & Hepatology, FOS may increase the following symptoms in people with limited tolerance to any form of fructose:

  • abdominal bloating
  • cramps
  • diarrhea
  • loose stool

May aggravate IBS

FOS may also have negative effects on people with irritable bowel syndrome (IBS), and in those with small intestinal bacterial overgrowth syndrome (SIBO). But, there is limited research and conflicting scientific results in these areas.

FOS are the subject of multiple scientific studies. Currently, there is no daily recommended dosage for FOS. When not overused, FOS may have many health benefits. When overused, FOS may cause gastric distress in some people. More research is still needed on the health benefits of FOS, but current data seem to point to its safety.