Inulin/ja: Difference between revisions

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=== Harvesting and extraction ===

[[Chicory]] root is the main source of [[extract|extraction]] for commercial production of inulin. The extraction process for inulin is similar to obtaining [[sugar]] from [[sugar beet]]s. After harvest, the chicory roots are sliced and washed, then soaked in a [[solvent]] (hot water or ethanol); the inulin is then isolated, purified, and spray dried. Inulin may also be [[chemical synthesis|synthesized]] from [[sucrose]].

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===Processed foods===

Inulin received no-objection status as [[generally recognized as safe]] (GRAS) from the [[Food and Drug Administration (United States)|US Food and Drug Administration (FDA)]], including long-chain inulin as GRAS. In the early 21st century, the use of inulin in processed foods was due in part to its adaptable characteristics for manufacturing. It is approved by the FDA as an ingredient to enhance the dietary fiber value of manufactured foods. Its flavor ranges from bland to subtly sweet (about 10% of the sweetness of sugar/sucrose). It can be used to replace sugar, fat, and flour. This is advantageous because inulin contains 25–35% of the [[food energy]] of carbohydrates (starch, sugar). In addition to being a versatile ingredient, inulin provides nutritional advantages by increasing [[calcium]] absorption and possibly [[magnesium]] absorption, while promoting the growth of intestinal [[bacteria]]. Chicory inulin is reported to increase absorption of calcium in young women with lower calcium absorption and in young men. In terms of nutrition, it is considered a form of [[Dietary fiber|soluble fiber]] and is sometimes categorized as a prebiotic. Conversely, it is also considered a [[FODMAP]], a class of carbohydrates which are rapidly fermented in the [[large intestine|colon]] producing gas. Although FODMAPs can cause certain digestive discomfort in some people, they produce potentially favorable alterations in the [[gut flora|intestinal flora]] that contribute to maintaining health of the colon.

Inulin and its analog [[sinistrin]] are used to help measure kidney function by determining the glomerular filtration rate (GFR), which is the volume of fluid filtered from the renal (kidney) [[Glomerulus (kidney)|glomerular]] capillaries into the [[Bowman's capsule]] per unit time.

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While inulin is the gold standard for measuring the GFR, it is rarely used in practice due to the expense and difficulty in conducting the test; it requires [[intravenous]] (IV) access for the infusion of inulin as well as up to twelve blood samples taken from the patient over the course of four hours. To determine the glomerular filtration rate in humans, a large initial dose of inulin is injected, which is followed by a constant infusion of inulin at a rate which compensates for its loss in the urine, thus maintaining a reasonably constant level in the plasma. In the United States, [[creatinine]] clearance is more widely used to estimate GFR.

A 2017 [[systematic review]] of low-to-moderate quality [[clinical trial]] research showed that [[dietary supplement|dietary supplementation]] with inulin-type [[fructans]] reduced blood levels of [[low-density cholesterol]], a [[biomarker]] of [[cardiovascular disease]].

The side effects of inulin dietary fiber diet, which may occur, usually in sensitive persons, are:

* [[Diarrhea]]

* [[Inflammation]] – inulin can cause an allergy-related type of inflammation in the gut and lungs

* [[Anaphylaxis|Anaphylactic allergic reaction]] (rare) – inulin is used for GFR testing, and in some isolated cases has resulted in an allergic reaction, possibly linked to a food allergy response.

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===Industrial use===

Inulins are [[polymer]]s composed mainly of fructose units ([[Fructan|fructans]]), and typically have a terminal [[glucose]]. The fructose units in inulins are joined by a β(2→1) [[glycosidic bond]]. The molecule is almost exclusively linear, with only a few percent branching. In general, plant inulins contain between 2 and 70 fructose units or sometimes as high as 200, but molecules with less than 10 units are called fructo-oligosaccharides, the simplest being 1-[[trisaccharide|kestose]], which has two fructose units and one glucose unit. Bacterial inulin is more highly branched (more than 15% branching) and contains on the order of tens or hundreds of subunits.

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Inulins are  named in the following manner, where '''n''' is the number of fructose residues and '''py''' is the abbreviation for [[pyranose|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'''.

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Hydrolysis of inulins may yield fructo-oligosaccharides, which are oligomers with a [[degree of polymerization]] (DP) of 10 or less.

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Inulin is uniquely treated by [[nephrons]] in that it is completely filtered at the [[glomerulus]] but neither secreted nor reabsorbed by the tubules.  This property of inulin allows the [[Clearance (medicine)|clearance]] of inulin to be used clinically as a highly accurate measure of glomerular filtration rate (GFR) — the rate of plasma from the [[afferent arteriole]] that is filtered into Bowman's capsule measured in ml/min.

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It is informative to contrast the properties of inulin with those of [[para-aminohippuric acid]] (PAH).  PAH is partially 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]]) is completely secreted.  Renal clearance of PAH is thus useful in calculation of renal plasma flow (RPF), which empirically is (1-[[hematocrit]]) times [[renal blood flow]].  Of note, the clearance of PAH is reflective only of RPF to portions of the kidney that deal with urine formation, and, thus, underestimates the actual RPF by about 10%.

The measurement of GFR by inulin or sinistrin is still considered the [[Gold standard (test)|gold standard]].  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]], [[iohexol]], [[cystatin C]], [[125I|¹²⁵I]]-[[iothalamate]] (sodium radioiothalamate), the chromium radioisotope [[chromium-51|⁵¹Cr]] (chelated with EDTA), and [[creatinine]], have had their utility confirmed in large cohorts of patients with chronic kidney disease.

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For both inulin and creatinine, the calculations involve concentrations in the urine and in the serum. However, unlike creatinine, inulin is not naturally present in the body. This is an advantage of inulin (because the amount infused will be known) and a disadvantage (because an infusion is necessary).

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Inulin is indigestible by the human [[enzyme]]s [[ptyalin]] and [[amylase]], which are adapted to digest starch. As a result, it passes through much of the [[digestive system]] intact. Only in the [[colon (anatomy)|colon]] do bacteria [[metabolism|metabolise]] inulin, with the release of significant quantities of [[carbon dioxide]], [[hydrogen]], and/or [[methane]]. Inulin-containing foods can be rather [[Flatulence|gassy]], in particular for those unaccustomed to inulin, and these foods should be consumed in moderation at first.

Inulin is a soluble fiber, one of three types of dietary fiber including [[soluble fiber|soluble]], [[insoluble fiber|insoluble]], and [[resistant starch]]. Soluble fiber dissolves in water to form a gelatinous material. Some soluble fibers may help lower blood cholesterol and glucose levels.

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Some traditional diets contain over 20 g per day of inulin or fructo-oligosaccharides. The diet of the prehistoric hunter-forager in the Chihuahuan Desert has been estimated to include 135 g per day of inulin-type fructans.  Many foods naturally high in inulin or fructo-oligosaccharides, such as chicory, garlic, and [[leek]], have been seen as "stimulants of good health" for centuries.

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As of 2013, no regulatory authority had permitted health claims in the marketing of prebiotics as a class.  Inulin's health effects had been studied in small clinical trials, which showed that it causes gastrointestinal adverse effects such as bloating and flatulence, does not affect [[Triglyceride|triglyceride levels]] or development of [[fatty liver]], may help prevent [[travelers' diarrhea]], and may help increase calcium absorption in adolescents.

* [[Agave]] (''Agave'' spp.)

* [[Banana]] and [[Cooking plantain|plantain]] ([[Musaceae]])

* [[Burdock]] (''Arctium lappa'')

* [[Camassia|Camas]] (''Camassia'' spp.)

* [[Chicory]] (''Cichorium intybus'')

* [[Echinacea|Coneflower]] (''[[Echinacea]]'' spp.)

* [[Mugwort]] root (''[[Artemisia vulgaris]]'')

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{{carbohydrates}}

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