Glucomannan

Glucomannanis a water-solublepolysaccharidethat is considered adietary fiber. It is ahemicellulosecomponent in thecell wallsof some plant species.  Glucomannan is afood additiveused as anemulsifierandthickener. It is a major source ofmannan oligosaccharide(MOS) found in nature, the other beinggalactomannan, which is insoluble.
Products containing glucomannan, under a variety of brand names, are marketed asdietary supplementswith claims they can relieve constipation and help lower cholesterol levels.Since 2010 they are legally marketed in Europe as helping with weight loss for people who are overweight and eating a diet with restricted calories,but as of 2020there was no good evidence that glucomannan helped weight loss.Glucomannan may lower LDL cholesterol by up to 10 percent, according to one meta-study.
Supplements containing glucomannans pose a risk for choking andbowel obstructionif they are not taken with sufficient water.Other adverse effects include diarrhea, belching, and bloating; in one study people taking glucomannans had higher triglyceride levels.
Glucomannans are also used to supplementanimal feedforfarmed animals, to cause the animalsgain weight more quickly.
Glucomannan is mainly a straight-chainpolymer, with a small amount of branching.  The component sugars are β-(1→4)-linkedD-mannoseandD-glucosein a ratio of 1.6:1.The degree of branching is about 8% through β-(1→6)-glucosyl linkages.
Glucomannan with α-(1→6)-linkedgalactoseunits in side branches is calledgalactoglucomannan.
In theyeastcell wall, mannan oligosaccharides are present in complex molecules that are linked to the protein moiety. There are two main locations of mannan oligosaccharides in the surface area ofSaccharomyces cerevisiaecell wall.
They can be attached to the cell wall proteins as part of –O and –N glycosyl groups and also constitute elements of large α-D-mannanose polysaccharides (α-D-Mannans), which are built of α-(1,2)- and α-(1,3)- D-mannose branches (from 1 to 5 rings long), which are attached to long α-(1,6)-D-mannose chains.
This specific combination of various functionalities involves mannan oligosaccharides-protein conjugates and highly hydrophilic and structurally variable 'brush-like' mannan oligosaccharides structures that can fit to various receptors of animal digestive tracts,and to the receptors on the surface of bacterial membranes,impacts these molecules' bioactivity. Mannan oligosaccharides-protein conjugates are involved in interactions with the animal's immune system and as result enhance immune system activity.They also play a role in animal antioxidant andantimutagenicdefense.
Glucomannan comprises 40% by dry weight of the roots, orcorm, of thekonjacplant. Another culinary source issalep, ground from the roots of certain orchids and used in Greek andTurkish cuisine. However, these orchid species are protected in the whole EU and the trade of salep is strictly forbidden. Glucomannan is also ahemicellulosethat is present in large amounts in the wood ofconifersand in smaller amounts in the wood ofdicotyledons.Glucomannan is also a constituent of bacterial, plant and yeast cell wall with differences in the branches or glycosidic linkages in the linear structure.
Glucomannan is afood additiveused as anemulsifierandthickenerwith theE numberE425(ii).
Glucomannan-richsaleppowder is responsible for the unique textural properties of salepdondurma, a mastic-flavored stretchable and chewy ice cream of Turkish origin.
Konjac, also rich in glucomannan, is widely used for its jelly-like texture. It found use inshirataki noodles, in fruit jellies snacks (with choking risk),and as a substitute for gelatin.
Glucomannan is an ingredient in a variety ofdietary supplementproducts marketed with claims that they aid inweight loss, but medical research has found no good evidence to support its use for this purpose.The claim is that it makes a gel when mixed with water, which can take up space in the stomach and linger there longer than water alone would, inducing a person to feel full after having eaten a smaller amount of food.
In Europe and Canada, glucomannan dietary supplements can be marketed with claims to lower cholesterol levels and to relieve constipation.
Data from a randomized controlled clinical trial suggests that glucomannan dietary supplements help regulate the hormone ghrelin and might help control appetite in people with Type 2 diabetes.
A health advisory was released byHealth Canadastating the following: "Natural health products containing the ingredient glucomannan in tablet, capsule or powder form, which are currently on the Canadian market, have a potential for harm if taken without at least 250 ml or 8 ounces of water or other fluid. The risk includes choking and/or blockage of the throat, esophagus or intestine, according to international adverse reaction case reports. It is also important to note that these products shouldnotbe taken immediately before going to bed."
Other adverse effects include diarrhea, belching, and bloating; in one study people taking glucomannans had higher triglyceride levels.
Several companies have been determined by theFederal Trade Commission(FTC) or theFood and Drug Administration(FDA) to have, at some time, violated theFederal Food, Drug, and Cosmetic Act.The companies includeVitacost,PediaLean,Herbal Worldwide Holdings,BioTrim,and others.  The company Obesity Research Institute, the marketer of FiberThin, Zylotrim, Propolene and Lipozene, settled FTC charges that their misleading weight-loss claims violated federal laws by agreeing to pay $1.5 million in consumer redress.
In 2001, a number of jelly-type candy products containing konjac-derived glucomannan were barred from import by the U.S.Food and Drug Administrationdue to choking hazards.
It is also used asdietary supplementfor farmed animals in order to help them gain more weight from food, called thefeed conversion ratio. The effect of mannan oligosaccharides on animal performance was analysed inmeta-analysesfor poultry,pigs,and calves.