Inulin is a slightly soluble fiber extracted from chicory roots or Jerusalem artichoke rhizomes. It is part of the constitution of a large number of dietary supplements.
It is a non-digestible and non-absorbable polysaccharide in the intestine. It is composed of many fructose units repeated to form long chains. Inulin has potential nutraceutical activities, such as the improvement of digestive function and the ability to act as a prebiotic.
In fact, this fiber would be used as a source of nourishment by the “good” bacteria of the intestinal microflora, which would proliferate to the detriment of the pathogenic bacteria from outside.
The conditional is a must. EFSA was forced to reject these nutritional claims of inulin due to a lack of sufficient scientific evidence. It recently opened to a positive evaluation of Beneo’s inulin for improving bowel function.
What is Inulin?
Famous for its presence in probiotic supplements useful for the well-being of the intestine and for the regulation of the bowel habit. It appears as a white, odorless, tasteless powder, formed by spheroidal granules and slightly soluble in water. It is obtained from Jerusalem artichoke tubers, chicory and scorzonera roots.
It belongs to the group of soluble fibers, that category of molecules which is not digested by the stomach and is not absorbed by the intestine. In fact, it is partially broken down and digested by the colon and its bacterial microflora.
At a purely chemical level, it is a polymer formed by repeating units of fructose. They arrange themselves to form long linear chains that are not digestible by the body, but only by species that are equipped with the hydrolytic enzyme inulinase.
Given its characteristics, it is used in the diagnostic medical field to test the glomerular filtration rate (GFR) and therefore renal function.
As regards its presence in food supplements and products useful for intestinal well-being, EFSA has not yet approved the claims, except that of Beneo’s inulin for the improvement of intestinal health and regularity.
If you are interested in the topic, discover our in-depth study on dietary fibers.
What is inulin used for: properties and benefits
Despite having various biological activities, it is mainly considered as a prebiotic for intestinal well-being. But most of the studies in this regard consist of experimental evidence that has not been approved by the EFSA and does not justify its “therapeutic indications”.
Properties and biological effects
Its main function is to be a prebiotic capable of supporting the vitality and functionality of the microbiota, and consequently the well-being of the entire intestine. The following biological effects are conferred.
- Improvement of the hive. Thanks to the ability of soluble fibers to increase intestinal mass and thus promote peristalsis (intestinal movements that allow the intestinal contents to move forward).
- Prebiotic action towards the “good” bacteria present in the intestinal microflora. These microorganisms derive nourishment from inulin, which is useful for their growth and proliferation. A healthy and intact microbiota is one of the first defensive barriers against the encroachment of pathogenic bacteria and microbes from the external environment and beyond.
- Metabolic activities useful in reducing the risk of hypercholesterolemia, hypertriglyceridemia and hyperglycemia. This function seems to be related both to the ability to modulate the absorption of lipids, sugars and cholesterol in the intestine, and to the production of short-chain fatty acids by the microflora. These fats, such as acetic acid, propionic acid, butyric acid and valeric acid, once absorbed are involved in the metabolic processes of fats and carbohydrates, improving them.
- Improved intestinal absorption of minerals such as calcium and magnesium.
Where is inulin found?
Inulin is a soluble fiber that abounds in many types of foods of vegetable origin and that in normal diet is taken in the amount of 3-10 g per day.
When it is taken, a small part is absorbed and therefore has a caloric value equal to 0 Kcal per 100 g, nor can it be defined as a caloric nutrient.
It is not only found in foods that occur naturally, but is also secretly ingested through other types of food products.
What are the foods rich in inulin?
It is mainly found in foods of plant origin, such as artichokes, asparagus, onions, leeks, Jerusalem artichokes, avocados, bananas and chicory.
It is therefore widely present in the diet of vegetarians, vegans or those who follow a diet that provides the right quantities of daily fiber.
Values that according to LARN (Recommended Intake Levels of Nutrients for the Italian Population) must be around 20-30 g/day (a higher quantity than what is currently consumed in our country).
How to take inulin
Many wonder, therefore, how inulin should be taken within one’s daily life.
The answer is very simple and involves a moderate\high consumption of foods of plant origin within one’s diet.
A healthy, varied and balanced diet will contain the right levels of fiber and inulin, without the need for external supplements.
In some cases, however, it may be necessary to take products that help improve or restore the functionality and well-being of the bacterial and intestinal microflora.
Following antibiotic therapies, intestinal dysbiosis or other problems that undermine the delicate balance of one’s intestinal microbiota, it may be necessary to take lactic ferments and probiotic and prebiotic supplements.
Some products are formulated with a mix of probiotics (“good” bacteria) and prebiotics (fibers such as inulin), useful for nourishing the beneficial bacteria of the microflora, promoting their correct proliferation.
Although the approved claims are small, there are many food supplements, dietary supplements and health products that contain inulin in them.
Some present inulin as an excipient or secondary functional ingredient, while others use it as the main component of the formulation. Sold in the form of tablets, powder or added to other foods, the recommended dosage of inulin is 5-10 g per day.
This parameter, added to the assumptions from the diet and the scarce confirmations deriving from EFSA and other competent authorities, advises against its intake in the form of a food supplement.
In fact, inulin levels exceeding 10 g per day could generate intestinal problems from colitis, meteorites and other digestive disorders.
Thanks to the neutral and slightly sweetish taste, it is also used as an additive ingredient which gives mass and body to the preparations, but without adding a particular taste.
It is used in the field of ice cream (especially as regards sugar-free products), in confectionery or in various other preparations that exploit the technological characteristics of inulin.
It is also often used to replace part of the fat, in light snacks and chocolate, and to prevent the cocoa butter from surfacing during the hot season.
A practical demonstration of the replacement of dietary fats with inulin comes from the Beneo-Technology Center, which without changing the flavor in any way, has reduced the fat content of Frankfurter (German sausages) to just 5%, simply by replacing the fat with lean parts in order to set the required fat content.
The taste and mouthfeel that are determined by the fat is achieved precisely through the use of inulin as a food additive.
Although present in numerous experimental studies, inulin has not received authorization from EFSA for nutritional claims, according to which the substance promotes the well-being of the intestinal flora and the reduction of cholesterol levels.
Action that should be led rather than to the mechanical effect of the soluble fiber, to the metabolic one induced by the fermentation residues of inulin.
In fact, when this polymer arrives in the intestine it is fermented by bacterial microflora (specifically by bifidobacteria), with the consequent formation of short-chain fatty acids, such as acetic acid, propionate and butyrate.
This type of fatty acids, according to studies, would have a trophic (nutritional) action on the enterocytes (intestinal cells), but also a systemic action of a metabolic nature on fats and sugars.
Specifically, these fatty acids would promote an inhibitory action against the HMG-CoA reductase enzyme, involved in the synthesis of endogenous cholesterol.
EFSA has also rejected all the claims that see inulin extracted from chicory as a regulator of blood cholesterol and the sense of satiety, and those that see it involved in the stimulation of the body’s immune defences.
There have been no reports of cases in which the intake of inulin-based supplements and food supplements interfered with the intake of other drugs or other substances ingested orally.
In general, the intake of this natural substance is considered safe, but possible side effects, especially on the gastrointestinal level, cannot be excluded.