What are fructo-oligosaccharides and what effects do they have on the body?

Fructo-oligosaccharides are increasingly present in functional foods and supplements. The reason is its possible health properties beyond the prebiotic effect

Written and verified by the nutritionist Anna Vilarrasa on August 28, 2021.

Last update: August 28, 2021

Fiber is an essential component of food for the body. There are different types of this substance with proven health benefits. This is the case with fructo-oligosaccharides.

Fructo-oligosaccharides (FOS) are a type of fiber made up of chains of fructose molecules. According to its length and composition, there are fructans and inulin. They are also known as 'oligofructose' or 'oligofructans'.

Fructo-oligosaccharides: a healthy soluble fiber

Onions contain fructo-oligosaccharides.

In a natural way, the fruit-oligosaccharides they are present in a good number of fruits and vegetables. Industry also extracts them by degrading inulin. In this case, they are used in prebiotic supplements or in the manufacture of some food products as sweetener additives.

They are considered a prebiotic substance with all the benefits that this entails for the body and health. For this reason, they have become an ingredient in many functional foods and dietary supplements in recent years. Nevertheless, the desired effects are not always obtained and in some people its intake may be uncomfortable. Also if they are ingested in large quantities.

Uses and benefits of fructo-oligosaccharides

FOS are a type of fiber that the body is not prepared to digest. For this reason, it reaches the colon intact where it is degraded by intestinal bacteria. This fermentation by the microbiota is what gives rise to a good part of its positive effects. As described by authors Carlson, Ericsson, Lloyd, and Slavin, the following are some of the recognized benefits for the general population.

Effects on the composition of the microbiota

As seen at the beginning, fibers with a prebiotic effect promote the growth of bacteria that are positive for the body. Some of those that are most benefited are lactobacilli and bifidobacteria.

These can improve health through different mechanisms. The former are known for facilitate the digestion of lactose, relieve constipation and help in case of traveler's diarrhea. The presence of bifidobacteria has been associated with obesity and weight control.

Generation of positive metabolites

After the fermentation of the fibers by the intestinal bacteria, a series of compounds are generated. These are residues or waste substances, but some are of great importance in maintaining the integrity of the intestine and for general health.

For example, Some short-chain fatty acids are a source of energy for the cells of the intestine and contribute to the integrity of the mucous layer. An anti-inflammatory and activating activity of T cells that would enhance the action of the immune system has also been observed.

Inhibition of the proliferation of harmful bacteria

The intestinal microbiota is one of the first protective barriers against some pathogens such as E. Coli, Salmonella, Clostridium or Campylobacter.

More benefits of fructo-oligosaccharides: protection against allergies

Good microbial diversity in the intestine influences the development of some inflammatory diseases; among them, also some allergic reactions. Reduced levels of lactobacillus and bifidobacteria have been associated with a higher incidence of allergies in children under 5 years of age.

Fructo-oligosaccharides supplementation has been shown to be effective for symptoms such as eczema and rhinoconjunctivitis, although the mechanisms of action are unknown and more evidence is needed to establish it as a preventive measure.

Mineral absorption

The acidic environment that is generated with the fermentation of fructo-oligosaccharides and other fibers stimulates the absorption of some minerals such as calcium. However, studies show contradictory results in this regard depending on the age and physiology of the participants.

Does its intake have contraindications?

Fructo-oligosaccharides naturally present in fruits and vegetables do not present problems in most people. In the case of the food industry, FOS is considered a GRAS substance by the US Food and Drug Administration.

This means that its use as a food additive is safe. Its presence is allowed in nutritional bars, breakfast cereals, drinks, juices, cookies, confectionery, fillings and toppings for desserts, creams, meat and fish substitutes, milk, jams and breads, among others.

However, its use and intake is not absent of side effects in some people and in certain quantities. What problems can fructo-oligosaccharides also cause?

Digestive discomfort

Sometimes, It is not uncommon for some symptoms of intolerance to this component to appear. The most common are nausea, bloating, fullness, gas, cramps, diarrhea and irritation of the intestinal mucosa. Some very sensitive people may have more severe allergic-type reactions.

Irritable bowel syndrome

Fructo-oligosaccharides may not be suitable for people with these types of digestive system problems. Neither in case of bacterial overgrowth (SIBO). While the studies are a bit confusing so far, a worsening of symptoms has been observed.

Non-beneficial bacteria growth

Prebiotics are food for the intestinal microbiota and, for this reason, could enhance the growth of non-beneficial flora.

Where they are found and how to include fructo-oligosaccharides in the diet

Bananas are among the foods with small amounts of fructo-oligosaccharides.

This type of fiber it is present in some foods that can be easily integrated into the diet. Those with the highest amounts are blue agave syrup, chicory root, garlic, onion, and Jerusalem artichokes.

In addition in small quantities they are also in:

  • Bananas, cantaloupe melon, peach.
  • Asparagus, artichokes, leeks, Brussels sprouts, beet root.
  • Yacón root (tuber from the Andean region).
  • Barley, wheat, rye.

Set up Infusions or drinks of water diluted with blue agave syrup is another way of ingesting FOS. Also the chicory root that is taken as a substitute for coffee (but without caffeine).

Commercial presentations and dosage

There are two other ways to ingest them. On the one hand, through fortified foods where they are added as sweeteners or as a prebiotic supplement. Its sweetening capacity is much higher than that of sugar and, in addition, it does not cause blood glucose spikes or promote tooth decay.

At the same time, There are fructo-oligosaccharide supplements either in powder or tablets. Some studies have shown positive results with doses ranging from 5 to 20-30 grams per day in adults.

For children, FOS has been given through fortified formula or cow's milk. The amounts are between 6 and 12 grams per kilo of weight depending on age and its main function is to improve constipation.

Nevertheless, Before taking any supplement, it is advisable to consult with your doctor or other health professional. Especially in case of taking medication or suffering from illnesses. Furthermore, FOS supplements are not indicated in pregnant or lactating women.

Fructo-oligosaccharides are beneficial to health, but must be ingested with care

In recent years, fructo-oligosaccharides are studied as food components with beneficial effects on health. For this reason, they are increasingly present in food and dietary supplements.

However, it is preferable to be cautious with its intake as it can also have annoying side effects and they are not always adequate. For this reason, it is recommended to consult a professional before taking them.

The good news is that with a regular consumption of small amounts of fruits and vegetables our body can already enjoy these components and take advantage of all the benefits that they can provide.