Inulin

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Inulin

Inulins are a group of naturally occurring polysaccharide

Polysaccharide

Polysaccharides are relatively complex carbohydrates. They are polymers made up of many monosaccharides joined together by glycosidic bonds. They are therefore very large, often branched, macromolecules....
s (several simple sugars linked together) produced by many types of plants. They belong to a class of fiber

Dietary fiber

Dietary fiber, sometimes called "roughage", is the indigestible portion of plant foods that pushes food through the digestive system, absorbing water and easing defecation....
s known as fructan

Fructan

A fructan is a polymer of fructose molecules. They occur in foods such as artichokes, asparagus, green beans, leek s, onions , yacon, and wheat....
s. Inulin is used by some plants as a means of storing energy and is typically found in root

Root

In vascular plants, the root is the organ of a plant body that typically lies below the surface of the soil. This is not always the case, however, since a root can also be aerial root or aerating ....
s or rhizome

Rhizome

In botany, a rhizome is a characteristically horizontal plant stem of a plant that is usually found underground, often sending out roots and shoots from its nodes....
s. Most plants which synthesize and store inulin do not store other materials such as starch

Starch

File:Amylose2.svgFile:Amylopektin Sessel.svgStarch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds....
.

in is used increasingly in foods because it has unusual nutritional characteristics.

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Encyclopedia

Inulins are a group of naturally occurring polysaccharide

Polysaccharide

Dietary fiber

Dietary fiber, sometimes called "roughage", is the indigestible portion of plant foods that pushes food through the digestive system, absorbing water and easing defecation....
s known as fructan

Fructan

Root

Rhizome

Starch

File:Amylose2.svgFile:Amylopektin Sessel.svgStarch or amylum is a polysaccharide carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds....
.

Uses

Processed foods

Inulin is used increasingly in foods because it has unusual nutritional characteristics. Its flavour ranges from completely bland to subtly sweet (approx. 10% sweetness of sugar/sucrose). It can be used to replace sugar, fat, and flour. This is particularly advantageous because inulin contains a third to a quarter of the food energy

Food energy

Food energy is the amount of energy in food that is available through digestion.Like other forms of energy, food energy is expressed in calories or joules....
of sugar or other carbohydrates and a sixth to a ninth of the food energy of fat. It also increases calcium

Calcium

Calcium is the chemical element with the symbol Ca and atomic number 20. It has an atomic mass of 40.078 amu. Calcium is a soft grey alkaline earth metal, and is the fifth most abundant element by mass in the earth's Crust ....
absorption and possibly magnesium

Magnesium

Magnesium is a chemical element with the symbol Mg, atomic number 12, atomic weight 24.3050 and common oxidation number +2.Magnesium, an alkaline earth metal, is the ninth most abundance of the chemical elements in the universe by mass....
absorption, while promoting the growth of intestinal bacteria

Bacteria

The Bacteria are a large group of unicellular microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals....
. Nutritionally, it is considered a form of soluble fiber

Dietary fiber

Dietary fiber, sometimes called "roughage", is the indigestible portion of plant foods that pushes food through the digestive system, absorbing water and easing defecation....
and is sometimes seen as a prebiotic. The consumption of large quantities (particularly by sensitive or unaccustomed individuals) can lead to gas and bloating. Inulin has a minimal impact on blood sugar

Blood sugar

Blood sugar concentration, or glucose level, refers to the amount of glucose present in a mammal's blood. Normally, the blood glucose level is maintained at a Reference_ranges_for_blood_tests#Electrolytes_and_Metabolites between about 4 and 6 mM ....
, and—unlike fructose—is not insulemic and does not raise triglycerides

Hypertriglyceridemia

In medicine, hypertriglyceridemia denotes high blood levels of triglycerides, the most abundant fatty molecule in most organisms. It has been associated with atherosclerosis, even in the absence of hypercholesterolemia ....
, making it generally considered suitable for diabetics and potentially helpful in managing blood sugar-related illnesses.

Industrial use

Nonhydrolyzed inulin can also be directly converted to ethanol

Ethanol

Ethanol, also called ethyl alcohol, pure alcohol, grain alcohol, or drinking alcohol, is a volatility , flammable, colorless liquid....
in a simultaneous saccharification and fermentation process which may have great potential for converting crops high in inulin into ethanol for fuel.

Medical

Inulin is used to help measure kidney function by determining the glomerular filtration rate (GFR). GFR is the volume of fluid filtered from the renal

Kidney

The kidneys are Organ that have numerous biological roles. Their primary role is to maintain the homeostasis balance of bodily fluids by filtering and secreting Metabolomics#Metabolitess and minerals from the blood and excreting them, along with water , as urine....
(kidney) glomerular capillaries into the Bowman's capsule

Bowman's capsule

The Bowman's capsule is a cup-like sac at the beginning of the tubular component of a nephron in the mammalian kidney. A glomerulus is enclosed in the sac....
per unit time.

Biochemistry

Inulins are polymer

Polymer

A polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds. While polymer in popular usage suggests plastic, the term actually refers to a large class of natural and synthetic materials with a variety of properties....
s mainly comprising fructose

Fructose

Fructose is a simple Reducing sugar sugar found in many foods and is one of the three important dietary monosaccharides along with glucose and galactose....
units and typically have a terminal glucose

Glucose

Glucose , a monosaccharide also known as grape sugar, blood sugar, or corn sugar, is a very important carbohydrate in biology....
. The fructose units in inulins are joined by a ß(2?1) glycosidic bond

Glycosidic bond

In chemistry, a glycosidic bond is a certain type of functional group that joins a carbohydrate molecule to another, which may be another carbohydrate....
. Plant inulins generally contain between 20 to several thousand fructose units. Smaller compounds are called fructooligosaccharide

Fructooligosaccharide

Fructooligosaccharides also sometimes called oligofructose or oligofructan, is a class of oligosaccharides used as an artificial or alternative sweetener....
s, the simplest being 1-ketose

Ketose

A ketose is a sugar containing one ketone group per molecule.With 3 carbon atoms, dihydroxyacetone is the simplest of all ketoses and is the only one having no optical activity....
, which has 2 fructose units and 1 glucose unit.

Inulins are named in the following manner, where n is the number of fructose residues and py is the abbreviation for pyranosyl:

Inulins with a terminal glucose are known as alpha-D-glucopyranosyl-[beta-D-fructofuranosyl](n-1)-D-fructofuranosides, abbreviated as GpyFn.
Inulins without glucose are beta-D-fructopyranosyl-[D-fructofuranosyl](n-1)-D-fructofuranosides, abbreviated as FpyFn.

Hydrolysis of inulins may yield fructooligosaccharide

Fructooligosaccharide

Degree of polymerization

The degree of polymerization, or DP, is the number of repeat units in an average polymer chain at time t in a polymerization reaction . The length is in monomer units....
(DP) of <= 10.

Calculation of glomerular filtration rate (GFR)

Inulin is uniquely treated by nephrons in that it is completely filtered at the glomerulus

Glomerulus

A glomerulus is a capillary tuft surrounded by Bowman's capsule in nephrons of the vertebrate kidney. It receives its blood supply from an afferent arteriole of the renal circulation....
but neither secreted nor reabsorbed by the tubules. This property of inulin allows the clearance

Clearance (medicine)

In medicine, the clearance is a measurement of the renal excretion ability. Although clearance may also involve other organs than the kidney, it is almost synonymous with renal clearance or renal plasma clearance....
of inulin to be used clinically as a highly accurate measure of glomerular filtration rate (GFR)—the percentage of plasma from the afferent arteriole that is filtered into Bowman's capsule

Bowman's capsule

The Bowman's capsule is a cup-like sac at the beginning of the tubular component of a nephron in the mammalian kidney. A glomerulus is enclosed in the sac....
.

It is useful to contrast the properties of inulin with those of para-aminohippuric acid (PAH). PAH is completely filtered from plasma at the glomerulus and not reabsorbed by the tubules, in a manner identical to inulin. PAH is different from inulin in that the fraction of PAH that bypasses the glomerulus and enters the nephron's tubular cells (via the peritubular capillaries

Peritubular capillaries

In the renal system, peritubular capillaries are tiny blood vessels that travel alongside nephrons allowing reabsorption and secretion between blood and the inner lumen of the nephron....
) is completely secreted. Renal clearance

Clearance (medicine)

In medicine, the clearance is a measurement of the renal excretion ability. Although clearance may also involve other organs than the kidney, it is almost synonymous with renal clearance or renal plasma clearance....
of PAH is thus useful in calculation of renal plasma flow (RPF), which empirically is (1-Hematocrit

Hematocrit

The hematocrit or packed cell volume or erythrocyte volume fraction is the proportion of blood volume that is occupied by red blood cells....
) times renal blood flow

Renal blood flow

In the renal physiology of the kidney, renal blood flow is the volume of blood delivered to the kidneys per unit time. In humans, the kidneys together receive roughly 25% of cardiac output, amounting to 1 L/min in a 70-kg adult male....
. Of note, the clearance of PAH is reflective only of RPF to portions of the kidney that deal with urine formation, and thus underestimates actually RPF by about 10%.

The measurement of GFR by inulin is still considered the gold-standard

Gold standard (test)

In medicine, gold standard test refers to a diagnostic test or benchmark that is regarded as definitive.This can refer to diagnosing a disease process, or the criteria by which scientific evidence is evaluated....
. Practically, however, it has now been largely replaced by other, simpler measures that are approximations of GFR. These measures, which involve clearance of such substrates as EDTA

EDTA

EDTA is a widely used acronym for the chemical compound ethylenediaminetetraacetic acid . EDTA is a polyamino carboxylic acid with the chemical formula [CH2N2]2....
, iso-hexanol, the radioisotope Chromium⁵¹ (chelated with EDTA

EDTA

EDTA is a widely used acronym for the chemical compound ethylenediaminetetraacetic acid . EDTA is a polyamino carboxylic acid with the chemical formula [CH2N2]2....
) and creatinine

Creatinine

Creatinine is a break-down product of creatine phosphate in muscle, and is usually produced at a fairly constant rate by the body ....
, have had their utility confirmed in large cohorts of patients with chronic kidney disease.

Health effects

Inulin is indigestible by the human enzyme

Enzyme

Enzymes are biomolecules that catalysis chemical reactions. Almost all enzymes are proteins. In enzymatic reactions, the molecules at the beginning of the process are called Substrate , and the enzyme converts them into different molecules, the products....
s ptyalin and amylase

Amylase

Amylase is an enzyme that breaks starch down into sugar. Amylase is present in human saliva, where it begins the chemical process of digestion....
, which are adapted to digest starch. As a result, inulin passes through much of the digestive system intact. It is only in the colon

Colon (anatomy)

The colon is the last portion of the digestive system in most vertebrates; it extracts water and salt from feces before they are defecation from the body....
that bacteria metabolise

Metabolism

Metabolism is the set of chemical reactions that occur in living organisms in order to maintain life. These processes allow organisms to grow and reproduce, maintain their structures, and respond to their environments....
inulin, with the release of significant quantities of carbon dioxide

Carbon dioxide

Carbon dioxide is a chemical compound composed of two oxygen atoms covalent bond to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state....
, hydrogen

Hydrogen

Hydrogen is the chemical element with atomic number 1. It is represented by the chemical symbol H. At standard temperature and pressure, hydrogen is a colorless, odorless, nonmetallic, tasteless, highly combustion and explosive Diatomic molecule gas with the molecular formula H2....
, and/or methane

Methane

Methane is a chemical compound with the molecular formula . It is the simplest alkane, and the principal component of natural gas. Methane's bond angles are 109.5 degrees....
. Inulin-containing foods can be rather gassy

Flatulence

Flatulence is the production of a mixture of gases in the gastrointestinal tract of mammals or other animals that are byproducts of the digestion process....
, particularly for those unaccustomed to inulin, and these foods should be consumed in moderation at first.

There are three types of dietary fiber

Dietary fiber

Resistant starch

Resistant starch is starch that escapes digestion in the small intestine of healthy individuals. Resistant starch is considered the third type of dietary fiber, as it can deliver some of the benefits of insoluble fiber and some of the benefits of soluble fiber....
. Insoluble fiber increases the movement of materials through the digestive system and increases stool bulk; it is especially helpful for those suffering from constipation or stool irregularity. Soluble fiber dissolves in water to form a gelatinous material. Some soluble fibres may help lower blood cholesterol and glucose levels. Inulin is considered a soluble fiber.

Because normal digestion

Digestion

Digestion is the mechanical and chemical breaking down of food into smaller components, to a form that can be Absorption, for instance, by a blood stream....
does not break inulin down into monosaccharide

Monosaccharide

Monosaccharides are the most basic unit of carbohydrates. They are the simplest form of sugar and are usually colorless, water-soluble, crystal solids....
s, it does not elevate blood sugar levels and may therefore be helpful in the management of diabetes. Inulin also stimulates the growth of bacteria in the gut. Inulin passes through the stomach

Stomach

In most mammals, the stomach is a hollow muscular organ of the gastrointestinal tract involved in the second phase of digestion, following mastication....
and duodenum

Duodenum

The duodenum is the first section of the small intestine in most higher vertebrates, including mammals, reptiles, and birds. In fish, the divisions of the small intestine are not as clear and the terms anterior intestine or proximal intestine may be used instead of duodenum....
undigested and is highly available to the gut bacterial flora

Bacterial flora

The bacterial flora is the whole system of bacteria in body cavities that have contact with the outside world. Every place shows another biochemical environment:...
. This makes it similar to resistant starch

Resistant starch

Lactic acid bacteria

The Lactic Acid Bacteria comprise a clade of Gram-positive, low-GuanineCytosine, acid-tolerant, generally non-sporulating, non-respiring rod or cocci that are associated by their common metabolic and physiological characteristics....
(LAB) in which the bacteria have to survive very challenging conditions through the gastrointestinal tract before they are able to colonize the gut.

Some traditional diets contain up to 20g per day of inulin or fructo-oligosaccharides

Fructooligosaccharide

Chicory

Common chicory is a bushy perennial plant herb with blue, lavender, or occasionally white flowers. It grows as a wild plant on roadsides in its native Europe, and in North America, where it has become naturalized....
, garlic

Garlic

Allium sativum L., commonly known as garlic, is a species in the onion family Alliaceae. Its close relatives include the onion, shallot, leek, and chive....
, and leek

Leek

The leek, Allium ampeloprasum var. porrum , also sometimes known as Allium porrum, is a vegetable which belongs, along with the onion and garlic, to the Alliaceae family....
, have been seen as "stimulants of good health" for centuries.

Inulin is also used in medical tests to measure the total amount of extracellular volume and determine the function of the kidneys.

Inulin is generally recognized as safe (GRAS

Gras

Gras is a Communes of France in the Ard?che Departments of France in southern France....
) by the FDA.

There is a single report of what is claimed to be an allergic reaction to inulin in the literature, but dietary inulin has small amounts of bacteria and fungal spores and this case is most likely to represent a reaction to one of these contaminants: every day billions of people eat inulin-containing foods, e.g. onions, without any suggestion of allergy.

About 30–40% of people in Central Europe

Central Europe

Central Europe is the region lying between the variously and vaguely defined areas of Eastern Europe and Western Europe Europe. In addition, Northern Europe, Southern Europe and Southeastern Europe may variously delimit or overlap into Central Europe....
suffer from fructose malabsorption

Fructose malabsorption

Fructose malabsorption or dietary fructose intolerance is a digestive disorder of the small intestine in which the fructose carrier in enterocytes is deficient....
. Since inulin is a fructan

Fructan

A fructan is a polymer of fructose molecules. They occur in foods such as artichokes, asparagus, green beans, leek s, onions , yacon, and wheat....
, excess dietary intake may lead to minor side effects such as increased flatulence and loosened bowel motions in those with fructose malabsorption. It is recommended that fructan intake for people with fructose malabsorption be kept to less than 0.5 grams/serving.

Natural sources of inulin

Plants that contain high concentrations of inulin include:

Elecampane
Elecampane

Elecampane, also called Horse-heal or Marchalan , is a Perennial plant composite plant common in many parts of Great Britain, and ranges throughout central and Southern Europe, and in Asia as far eastwards as the Himalayas....
(Inula helenium)
Dandelion (Taraxacum officinale)
Wild Yam (Dioscorea
Dioscorea

Dioscorea is a genus of over 600 species of flowering plants in the family Dioscoreaceae, native throughout the tropical and warm temperate regions of the world....
spp.)
Jerusalem artichoke
Jerusalem artichoke

The Jerusalem artichoke , also called the sunroot or sunchoke or earth apple or topinambur, is a species of Helianthus native to the eastern United States, from Maine west to North Dakota, and south to northern Florida and Texas....
s (Helianthus tuberosus)
Chicory
Chicory

Common chicory is a bushy perennial plant herb with blue, lavender, or occasionally white flowers. It grows as a wild plant on roadsides in its native Europe, and in North America, where it has become naturalized....
(Cichorium intybus)
Jicama
Jícama

J?cama , also Mexican Potato and Mexican Turnip, is the name of a native Mexican vine, although the name most commonly refers to the plant's edible tuberous root....
(Pachyrhizus erosus)
Burdock
Burdock

Burdock is any of a group of Biennial plant thistles in the genus Arctium, family Asteraceae. Native to the Old World, several species have been widely introduced worldwide....
(Arctium lappa)
Onion
Onion

Onion is a term used for many plants in the genus Allium. They are known by the common name "onion" but, used without qualifiers, it usually refers to Allium cepa....
(Allium cepa)
Garlic
Garlic

Allium sativum L., commonly known as garlic, is a species in the onion family Alliaceae. Its close relatives include the onion, shallot, leek, and chive....
(Allium sativum)
Agave
Agave

Agave is a succulent plant plant of a large botanical genus of the same name, belonging to the family Agavaceae....
(Agave spp.)
Yacón
Yacón

The Yac?n is a perennial plant grown in the Andes of Per? for its crisp, sweet-tasting tubers. The texture and flavour have been described as a cross between a fresh apple and watermelon which is why it is sometimes referred to as the apple of the earth....
(Smallanthus sonchifolius spp.)