Generality
FOS, acronym for fructo-oligosaccharides, are soluble fibers found in various common fruits, vegetables and plants.
The best known source of fructo-oligosaccharides is inulin, from which the other FOS are obtained by enzymatic hydrolysis.Inulin, in turn, is obtained mainly from chicory root, but is also present in onions, garlic, artichokes, bananas, leeks, asparagus, rye and wheat.
From a chemical point of view, fructo-oligosaccharides consist of 3-5 units of monosaccharides (D-glucose and D-fructose).
FOS are very important in the nutritional and health fields, where they are used as "artificial" sweeteners and above all as prebiotics.
This last term identifies a group of indigestible substances for man but not for the bacterial flora that colonizes his intestine.
- they are neither absorbed nor hydrolyzed in the first part of the digestive tract;
- they selectively stimulate the growth and / or activity of a limited number of bacteria in the colon;
- positively modify the relationship between symbiotic microorganisms ("friends") and pathogens;
- induce positive luminal or systemic effects for human health.
Indications
Why are FOS used? What are they for?
The FOS exert a beneficial action on the intestinal microbiota, safeguarding its biodiversity and functionality.
The microbiota or intestinal flora is the set of microorganisms that populate the human gastrointestinal system in a symbiotic mutualism.
The clinical applications of FOS would therefore be attributed both to the aforementioned functional activity and to the mechanical activity, as fibers.
At the moment, FOS are used:
- As intestinal regularizers, both for the mass-forming action and for the activity on the microbiota;
- As a digestive aid in case of dyspepsia;
- As useful supplements in the course of dysmetabolisms such as hypertriglyceridemia and hypercholesterolemia;
- As useful remedies to rebuild an adequate intestinal flora, after antibiotic therapy;
- As supplements useful in rebalancing the absorption of minerals, such as calcium and magnesium.
The FOS are indicated in case of:
- constipation
- digestive deficiencies and gastrointestinal disorders (colitis, diarrhea, bloating)
- hypercholesterolemia and hypertriglyceridemia
- rebalancing of the bacterial flora after antibiotic therapy
Less characterized, but particularly interesting, would also be the potential functions of FOS as immunomodulating, antibacterial and protective agents against colorectal cancer.
Properties and Effectiveness
What benefits have the FOS shown?
The numerous biological functions of FOS, amply documented both by experimental studies and by large clinical trials, would mostly be attributable to the direct action against the intestinal microbiota.
Once taken, the FOS reach almost unchanged the cecum and the colon, where they selectively stimulate the growth and metabolic activity of beneficial strains, such as bifidobacteria. infantis, adolescentis and longum. These probiotic bacteria use FOS sugars to grow and reproduce, producing short-chain organic acids (acetic, lactic and formic) that inhibit the growth of pathogens.
The aforementioned activity justifies the functional and metabolic role of FOS.
FOS and cancer
The antitumor action of FOS would seem mostly linked to the increase in the concentrations of butyric acid and other short-chain fatty acids, which would follow the ingestion of these nutrients.
The short-chain fatty acids would exert a mucoprotective activity, protecting the intestinal mucosa from the damaging action of potential irritants and at the same time modulating the normal turnover of enterocytes.
FOS and metabolisms
The same short-chain fatty acids seem to intervene in the control of the activity of some important enzymes involved in the synthesis of cholesterol.
In fact, regular intake of FOS would seem to be associated with a significant reduction in blood concentrations of both triglycerides and LDL cholesterol, thus exerting an important preventive action against possible cardiovascular complications.
FOS and intestinal infections
The antiseptic action of FOS should be attributed both to the production of short-chain fatty acids, some of which with direct antibacterial functions, and to the ability to increase the vitality of Bifidobacteria and Lactobacilli. These microorganisms are in fact able to actively compete with the various pathogens, such as clostridia, salmonella, candida, staphylococci, shigelle and others.
FOS and minerals
The protective action of short-chain fatty acids would also seem valuable against chronic-degenerative pathologies such as osteoporosis.
Through mechanisms not yet fully known, the use of FOS and the consequent production of short-chain fatty acids would seem to enhance the absorption profile of minerals such as calcium and magnesium.
Dosage and method of use
How to use the FOS
The FOS are present on the market as:
- prebiotic food supplements;
- symbiotic food supplements, where they are therefore associated with probiotics (bacteria with a protective function);
- functional food ingredients.
The dosage generally used is that between 4 and 10 g per day, which has proved effective and safe.
The nutritional supplements based on fructo-oligosaccharides are presented as a white powder, with a sweetish taste, generally pleasant and easily soluble.
Side effects
At the recommended intake doses (2-10 g / day) the fructo-oligosaccharides are well tolerated.
For this reason, even the most delicate subjects such as pregnant women, the elderly and children can safely take FOS-based supplements.
Higher dosages could result in the onset of
- meteorism (common at intake doses above 30g / day)
- borborygmas and intestinal bloating (common at intake doses above 40g / day)
- cramps and diarrhea (common at intake doses above 50g / day)
However, the same symptoms could also occur at lower doses in particularly predisposed patients.
When should FOSs not be used?
The use of FOS is contraindicated in case of hypersensitivity to the substances contained and to inulin.
Pharmacological interactions
What drugs or foods can modify the effect of FOS?
There are currently no noteworthy drug interactions between FOS and other active ingredients.
Precautions for use
What do you need to know before taking FOS?
The use of FOS should be carried out with particular caution in patients suffering from irritable bowel syndrome, abdominal swelling, alternate alvus and other gastro-enteric symptoms attributable to fiber intake.
The same caution should be used by patients suffering from lactose intolerance; they should avoid taking doses higher than 10g.
In-depth video: Inulin and prebiotics
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