Inulin can be defined as a carbohydrate for energy storage with structural and functional characteristics of a soluble fiber. This fact will set it apart from other carbohydrates, like starch, that lack this structural particularity which, as we will see in this article, is of great importance for the basic function of inulin within the organism.
If we take a closer look to its chemical nature, we will see that it belongs to the family of compounds called Fructans.
These are the most abundant type of polysaccharides in nature (found in plants, fungus and bacterium), and they are classified as oligosaccharides, ie, a basic group of a few simple sugar molecules. The inulin molecule is highly water soluble and is integrated by non-branched chains formed of 40 to 100 molecules of fructose (the simple sugar that constitutes the core of its composition).
Which is the origin of inulin?
Was first isolated and purified at the beginning of the 19th century, from the species Inula Helenium (commonly known as horse-heal or elfdock), a perennial leaf plant, with the profile of a rather rigid herb. It is highly extended throughout the British Isles, and the South and Centre of Europe and Asia.
More than 36000 species have in common the presence of Inulin as a storage carbohydrate, providing an idea of the importance of this substance in vegetable metabolism.
Most of the plant species that store remarkable amounts of inulin do not usually do so in their vegetative part, that is to say, the leaves and stems, rather in the hypogeum or underground part (root, bulb, tuber, rhizome…). An exception to this rule is the grass family, which contain high concentrations in their green structures, although this is a disadvantage when it comes to the extraction for industrial purposes.
In fact, plants that can be considered suitable for industrial use as a source of fructosans are not abundant. If we go back ten years ago, inulin could only be obtained from sunroot (tuberculated plant similar to sunflower) and chicory, with a clear predominance of the latter.
Industrial uses of inulin
Independently of its dietary uses, which is the main purpose of this article, inulin is a compound widely recognized in the food industry for its technological attributes.
Among other possibilities, it is suitable to improve texture and stability of food products that are very different from each other such as dairy products, baked doughs, processed cereals and even some heat-treated meat products such as cold cuts.
The customer’s demands are gradually turning towards ‘light products’ but at the same time maintain an exquisite taste, an objective that is achievable to a large extent with the inulin resource. In fact, the meat products that include it, as a substitute for saturated fats, maintain a complete and intense flavour, while its low fat content makes them much healthier.
For this reason, there is a growing tendency to incorporate inulin as an ingredient, not an additive, into the production processes of various foods. By including this element, different effects can be sought, such as reduce saturated fats, especially in meat products, dairy products and ice creams, which will also reduce production costs, or grant a slightly sweet taste to food that need it (remember, its chemical basis is simple sugars).
In particular, inulin represents an excellent option to be able to supply more lean meat to our diet, by reducing the fat content of sausages and other meat products.
This fat replacement making it lean meat, in theory, would negatively affect the palatability or taste generated by the food, but it is precisely inulin that prevents this from happening. How? Simply, by means of the formation of a gel when entering in contact with water and being subjected to a sheering effect that increases the cutting pressure.
This gel gives the finished product a texture in the mouth completely comparable to that produced by the substituted fat globules.
This technological capacity of inulin sets it apart from the insoluble fibers, as it can replace fat thanks to its capacity to immobilize water during the formation of the gel, ability which the insoluble fibers lack. A further advantage is that it does not interfere with the flavor thanks to its neutrality in this aspect.
Consequently, we are talking of a successful field of action for the meat industry, because, it is an easy to manage substance, technologically speaking, and it improves the structure of the final product, resulting to be in some processes a factor of increase of the production.
But let's examine the use of inulin in some meat products:
Frankfurter hot dogs
Without altering the structure of its production process and adjusting to its classical composition, it is a fact that by replacing fat with lean ingredients, a reduction of the fat content of Frankfurt sausages to 5% is achieved.
This achievement is associated with the preservation of the genuine taste of this food, something that is possible by including inulin at a 5% concentration of the product mass. On the other hand, the appetite of this substance for water allows to increase the addition of ice at a rate of two kilos per kilo of inulin.
Liver sausages and pates
Inulin provides these products with an excellent unctuous property grease that improves their ability to be spread on bread. Its technological relevance in these foods is such that the fat content of the final product does not exceed 10%, being achieved by incorporating into the manufacturing process a gel that is prepared with double amount of water than inulin.
The fact that the cutting surface of the salami is visually characterized by macroscopic fat particles partially limits the inulin options in this product. On the other hand, the microbiological stability of this food requires low values of activity-water (the water available, that is to say, not chemically bound to large molecules), which in turn conditions the amount of water that can be added for the gel formation. But it has been proven experimentally that inulin improves the structure of the salami, making it possible to be produced with 12% fat.
Medical uses of inulin
Inulin has a long history in being used for the measurement of a clinical parameter known as glomerular filtration rate (GFR), which is useful to extract information on the renal capacity to filtrate a blood volume per time unit. It is especially suitable for this purpose, due to the fact that it is resistant to the degrading activity of the enzymes. Consequently, the filtration will be practically of 100% in the renal glomeruli, without reabsorption or excretion.
In a therapeutic context, its administration has been suggested for the specific treatment against pathologies such as Crohn's disease, ulcerative colitis, primary hypercholesterolemia and chronic constipation.
The main benefits and properties of inulin
The substance in question has an immense potential in relation to its contribution to the well-being and health of people, that find themselves in different situations. We will further expound on the most significant properties.
It promotes intestinal peristalsis, basically at the height of the colon, as it reaches the intestine practically intact. This causes a regulation of the transit of the fecal bolus through the digestive tract, which is also supported by the fact that it stimulates the growth of the intestinal flora. This function is exerted due to its prebiotic condition, as it decreases the pH of the medium and constitutes an excellent substrate for the growth of beneficial microorganisms, making a special mention to those known as bifidobacteria and lactobacilli.
It is especially effective for the control of anomalous intestinal fermentations, thus reducing flatulence.
It improves the intestinal absorption of some of what are considered to be macrominerals, like calcium, magnesium and phosphorus. If we focus on the first of these nutrients, it seems to be demonstrated that it intervenes in maintaining an adequate density of the bone matrix, a key point in the triggering of osteoporosis.
From this hypercalcemic effect the conclusion can be drawn that a regular intake is advisable in children (of special interest to ensure a correct bone mineralization), adolescents, pregnant women and the elderly.
It helps to stabilize the rate of insulin synthesis and, consequently, the level of insulin and blood glucose, which gives it an important role in the control and prevention of diabetes.
Simultaneously, it is an effective tool to keep cholesterol levels at bay (mainly LDL, commonly called "bad cholesterol") and inhibit the accumulation of triglycerides in the liver. Therefore, it may be an adjuvant in the prevention strategy of atherosclerosis and subsequent heart diseases and cardiovascular events.
The absorption of vitamins is optimized, especially those of the B vitamins, that intervenes nearly in all of the bodily functions.
Its energetic value is poor (the metabolization of one gram of inulin provides 1.5 kilocalories), therefore it can be said that it I ideal to be included in diets that are aimed at weight control.
In obese people an adequate ingest of inulin may positively modify the intestinal bacterial flora population, which may result in a touchstone to initiate the weight reduction and mitigate the risk of being a victim of diabetes, obesity being a clear predisposition factor (of a large group) for its onset.
A second route of control of diabetes type II could be through the direct antioxidant effect exerted by inulin. The oxidative stress produced by a prolonged action of high levels of blood circulating insulin is considered to be a determining factor for developing diabetes and the inherent complications that it entails. It seems to be that inulin can neutralize this phenomenon via its antioxidant action.
The two prime consequences that are worth making mention to, from ensuring a sufficient dietary supply of this fructan, are: the guarantee of a strong immune system and an increased fluidity in the gastrointestinal transit, that work synergistically to reduce the accumulation of toxic substances in the body.
Part of functional foods
Functional foods are those that thanks to their composition provide the body with substances that are necessary to maintain a good state of health. They are subject to a legal regulation by the European Union institutions responsible for the consumer protection laws. In fact, inulin is recognized as a safe substance by the official food competent authorities, dating back to 2007 the authorization to be included in industrial food processes in Europe.
The classification of this food group is highly complex and detailed, and its nutritional profiles cover a wide spectrum, as each one can contain different active principles that confer it with a certain characteristic.
Thus, among the principles that are legally accepted to belong to a functional food we will find inulin. It follows that any ready food, whether natural or processed, for the mere fact of containing a minimum amount of inulin in its composition is considered functional food.
Other substances with prebiotic effects
The following oligosaccharides are currently considered as functional:
Oligosaccharides: contained in protein crops such as soy, among which we can mention raffinose and stachyose.
Isomalto-oligosaccharides: are extracted by a hydrolysis process of the starch found in abundance in the grains of cereals and tubers; We can benefit from them by consuming fermented foods like rice miso (made with soy and brown rice) or sake (Japanese alcoholic beverage made from rice).
Galacto-oligosaccharides: are substances that are obtained from the galactose (a sugar) of the milk.
Lactulose: likewise obtained from milk, in this case by treating the lactose at high temperatures.
What food contains inulin?
When facing the task of elaborating a list of food that will ensure an adequate supply of this fiber oligosaccharide, the range of possibilities to choose from is not extremely ample, but in any case it may result sufficient.
Let us look at some examples.
This vegetable, also known as sunroot, sunchoke, earth apple or topinambour, is a variant of the sunflower (belonging to the same genus) and can reach up to 3 meters in height.
It is cultivated to obtain its tubercle, of a yellowish or violet bark, and white meat. With a flavor that resembles in a certain way that of the artichoke or truffle.
Jerusalem artichoke is nutritionally characterized by the fact that between 14 and 20% of its weight is inulin, reason for which it is positioned as the star food for contributing this nutrient.
As a reference, the conventional artichoke remains at a maximum composition of 8% of its weight in inulin.
As noted at the beginning of this article, chicory root is the main source of inulin, along with sunroot, for the food industry. The content percentage of inulin in its composition is very similar to that of sunroot, this is why it shares the first place as a source of this natural fiber.
Obviously, chicory root is not a raw material of easy use in cooking, but this should not be an obstacle for its consumption because there are processed foods that contain it, for example some supplement bars that can be eaten as snacks, which will also allow us to benefit from the properties of inulin.
Leek, Onion and Garlic
The bulbs of these three plants, related to each other, are excellent natural sources of inulin. Between 3 and 10% of the weight of a leek, 2 to 6% in the case of an onion and 9 to 16% in a garlic are the percentages of inulin content. Therefore, we should not underestimate the inclusion of these luxury ingredients when making stews, soups and sauces, as they do not only serve to increase the amount of inulin in our diet, but also have a variety of nutritional properties that we should not turn down.
Although endowed with other physical features, it belongs to the same family as the previous three, liliaceae. This vegetable is highly abundant in minerals of a high metabolic value, folate and, of course, inulin, with approximately 3%. This results in a widely known fact: regular intake of asparagus stimulates the population of beneficial bacteria that compete to grow in the colon, for space and nutrients, with pathogens that cause diseases.
This fruit provides quantities of inulin that are significantly lower than those of the foods that are at the top this list, with amounts of about 0.7%. Consequently, the prebiotic effect of bananas is relatively scarce if we contrast it with chicory root and Jerusalem artichoke, but their contribution to increasing the contribution of inulin should not be neglected.
Rye and Barley
These are two cereals that are present in this list due to the fact that 0.5-1% of its composition is inulin, in the case of rye, and that content raises to 1-1.5% in barley. A good way of incorporating this oligosaccharide into our diet using this natural source would be to eat bread made from rye flour. In addition, many bars designed to be a part of weight control diets contain this substance among its ingredients.
Perennial herbaceous plant that can be commonly seen in meadows and gardens, to the point that sometimes it is confused with a weed.
Widely distributed throughout Europe, it has exceptional nutritional qualities, for example it is a rich source of flavonoids, as well as inulin, that is present in the root, which is also rich in levulin. Its dry extract (each gram of dry extract needs 5 grams of plant) provides 120 mg of this fructan per daily recommended dose. It can also be consumed in capsules, a format that facilitates the dosage.
Agave juice and honey
It is a globe shaped shrub, which can contain from 18 to 22% inulin in its composition; When the flowering begins, it is harvested to be extracted. What is consumed is the concentrated and dehydrated agave juice. It can also be used to produce agave honey, by heat treating that juice in such a way that the fructose chains are broken down.
How to take Inulin
Once described the incredible benefits provided by this substance, it is easy to understand that it is advisable for it to be present in a balanced diet.
The fact that in any kitchen we can easily find onions, garlics or leeks, that are some of the main natural sources of this ingredient, greatly facilitates it entering our daily menu.
Chicory root extract may appear in the formulas of some of the vitamin supplements and other supplements that are designed for weight loss diets.
In any case, although it is clear that inulin can behave as a great health ally, the decision to resort to a regular consumption of processed inulin (ie, not directly from food) always makes it recommendable to consult a doctor or pharmacist to obtain advise on the quantities that should be taken. This way, we may prevent that such a potentially valuable product may end up producing, for example, diarrhoea episodes due to an over-consumption.
For the purchase of an inulin synthesis formula, it is best to turn to an establishment specialized in selling organic products. Generally they come in a powder format, consumed in different ways and for different purposes:
Treatment to fight symptoms of gastritis or colitis
A cup of chamomile tea on an empty stomach, with a spoonful of inulin powder and without adding any sweetener, neither natural or synthetic. This treatment should be combined with the consumption of two liter of water a day, avoiding sugar-sweetened drinks.
Treatment to reduce cholesterol or triglycerides or for losing weight
A dandelion infusion, with a teaspoon of inulin powder, avoiding the consumption of sugar, white flour or cow milk, and drinking two liters of water daily. It should be done twice: in the morning, once on an empty stomach and another at night.
Treatment for constipation
Constipation is a health problem that should not be considered of minor importance, as a large accumulation of toxins is produced.
A daily infusion of flax seeds adding a spoonful of inulin is ideal to return intestinal transit to normality.
Preferably during two days, the solid food that is consumed should be limited to papaya, to progressively incorporate raw or steamed vegetables. And it is important to eliminate from the diet, for at least a length of time of a month, red meats and poultry, flours, refined sugars and cold meats. A daily supplementation with 15 grams of inulin will improve life quality of the elderly people who suffer from this.
Treatment of diabetes
It is evident that insulin relieves the body from abrupt changes in the levels of insulin, as the main substance that is generates when it is metabolized is fructose. Fructose does not act as a stimulant of the synthesis of insulin and its subsequent transformation takes place in the liver, via a metabolic processed called gluconeogenesis.
In addition, it can also be transformed into fat through lipogenesis, although this phenomenon is also not dependent on insulin to be able to reach the cells. For all this, inulin has an exceptional space within the diets of diabetics, while it is advisable to consult a doctor before following a supplement consumption regime.
It is a dietary supplement of interest, that is sold both in shops specialized in dietary and nutritional products, and in supermarkets. It is obtained from drying agave, the same plant from which tequila is made.
It can also be used as an ingredient to prepare desserts, as it works as an humectant or humidity retainer. Similarly it can be added to juices, shakes and drinks of all sorts.
Possible side effects and contraindications of inulin
Logically, inulin is not a substance devoid of situations in which its consumption is advised against, because some people may be sensitive to it. For example, it may produce adverse effects in people that suffer from fructose malabsorption syndrome, for who inulin may be a problem and should limit its consumption to half a gram.
Its soluble fiber nature leads to large intestine fermentations that can be the cause of suffering from gases, swelling, abdominal pains and diarrhoea.
Therefore, it is recommended that it should be added to the diet in a progressive manner, for the intestine to gradually get used to it. It is convenient to be guided by a professional to avoid undesired consequences.
In conclusion, taking a minimum of five grams of inulin in your daily diet will at least guarantee having good digestions and avoiding the discomfort of a swelled stomach. There are opinions in favour of increasing this dose to 40 grams a day, but between 10 and 14 grams a day should be enough to enjoy its properties.
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