Glucomannan
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2008-06-23T15:48:21Z
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'''Glucomannan''' is a water-soluble [[polysaccharide]] that is considered a [[dietary fiber]]. Glucomannan is a [[food additive]] used as an [[emulsifier]] and [[thickener]]. Products containing glucomanan, marketed under a variety of brand names, are also sold as nutritional supplements for [[constipation]], [[obesity]], [[high cholesterol]], [[acne vulgaris]] and [[type 2 diabetes]]. Though there is some clinical support for potential health benefits, the U.S. [[Food and Drug Administration]] (FDA) has not approved any product containing glucomannan for the treatment of these medical conditions. Several companies selling products containing glucomanna have been disciplined by the U.S. [[Federal Trade Commission]] (FTC) for misleading or exaggerated claims pertaining to the health benefits of glucomannan supplements.
==Chemistry==
Glucomannan is mainly a straight-chain polymer, with a small amount of branching. The component sugars are β-(1→4)-linked [[mannose|<small>D</small>-mannose]] and [[glucose|<small>D</small>-glucose]] in a ratio of 1.6:1.<ref>{{cite journal| doi=10.1016/S0144-8617(03)00039-0| title=Constitution of konjac glucomannan: chemical analysis and 13C NMR spectroscopy |author=Kaname Katsuraya, Kohsaku Okuyamab, Kenichi Hatanakab, Ryuichi Oshimab, Takaya Satoc, and Kei Matsuzakic| journal=Carbohydrate Polymers| volume=53 |issue =2|year =2003| pages= 183–189}}</ref> The degree of branching is about 8% through β-(1→6)-glucosyl linkages.
==Natural sources==
Glucomannan comprises 40% by dry weight of the roots or [[corm]] of the [[konjac]] plant. It is also a [[hemicellulose]] that is present in large amounts in the wood of [[conifer]]s and in smaller amounts in the wood of [[dicotyledon]]s.
==Potential health benefits==
Clinical and pre-clinical studies have shown several potential health benefits of glucomannan.
===Constipation===
Glucomannan is a soluble fiber, and as such, has been investigated for the treatment of constipation. Glucomannan may relieve constipation by decreasing fecal transit time.<ref>{{cite journal |author=Marzio L, Del Bianco R, Donne MD, Pieramico O, Cuccurullo F |title=Mouth-to-cecum transit time in patients affected by chronic constipation: effect of glucomannan |journal=Am. J. Gastroenterol. |volume=84 |issue=8 |pages=888–91 |year=1989 |month=August |pmid=2547312 |doi= |url=}}</ref> In the treatment of chronic constipation, glucomannan significantly improved symptoms of constipation while being well-tolerated and free of relevant side effects.<ref>{{cite journal |author=Passaretti S, Franzoni M, Comin U, ''et al'' |title=Action of glucomannans on complaints in patients affected with chronic constipation: a multicentric clinical evaluation |journal=Ital J Gastroenterol |volume=23 |issue=7 |pages=421–5 |year=1991 |pmid=1742540 |doi= |url=}}</ref>
===Obesity===
Clinical evidence suggests glucomannan may be beneficial in [[weight loss]].<ref>{{cite journal |author=Keithley J, Swanson B |title=Glucomannan and obesity: a critical review |journal=Altern Ther Health Med |volume=11 |issue=6 |pages=30–4 |year=2005 |pmid=16320857 |doi= |url=}}</ref> Because it is a soluble fiber, it absorbs water to form a [[viscosity|viscous]] gel-like mass. This mass may promote feelings of [[satiety]] while traveling through the [[gastrointestinal tract]]. In obese patients, taking 1 gram of glucomannan with 8 [[fluid ounce|ounces]] (250 ml) of water 1 hour before each of 3 meals daily over 8 weeks resulted in an average weight loss of 5.5 [[pound (mass)|pound]]s (2.5 kg).<ref name="Walsh">{{cite journal |author=Walsh DE, Yaghoubian V, Behforooz A |title=Effect of glucomannan on obese patients: a clinical study |journal=Int J Obes |volume=8 |issue=4 |pages=289–93 |year=1984 |pmid=6096282 |doi= |url=}}</ref>
===Cholesterol and other lipids===
Glucomannan has demonstrated statistically significant improvements in the total [[cholesterol]] of ''obese'' patients.<ref name="Walsh"/> In healthy men, 4 weeks of taking 3.9 grams of glucomannan decreased total cholesterol, [[low-density lipoprotein]], [[triglyceride]]s, and [[systolic blood pressure]]; notably, triglycerides dropped by 23%.<ref>{{cite journal |author=Arvill A, Bodin L |title=Effect of short-term ingestion of konjac glucomannan on serum cholesterol in healthy men |journal=Am. J. Clin. Nutr. |volume=61 |issue=3 |pages=585–9 |year=1995 |month=March |pmid=7872224 |doi= |url=http://www.ajcn.org/cgi/pmidlookup?view=long&pmid=7872224}}</ref> Glucomannan has also been tested in children with high cholesterol in conjunction with a diet. Interestingly, greater decreases in total cholesterol and [[low-density lipoprotein]] were observed in female children when compared to male children.<ref>{{cite journal |author=Martino F, Martino E, Morrone F, Carnevali E, Forcone R, Niglio T |title=Effect of dietary supplementation with glucomannan on plasma total cholesterol and low density lipoprotein cholesterol in hypercholesterolemic children |journal=Nutr Metab Cardiovasc Dis |volume=15 |issue=3 |pages=174–80 |year=2005 |month=June |pmid=15955465 |doi=10.1016/j.numecd.2004.04.004 |url=}}</ref> When used in conjunction with [[chitosan]], glucomannan decreases serum cholesterol possibly by increasing [[steroid]] excretion via the [[feces]].<ref>{{cite journal |author=Gallaher DD, Gallaher CM, Mahrt GJ, ''et al'' |title=A glucomannan and chitosan fiber supplement decreases plasma cholesterol and increases cholesterol excretion in overweight normocholesterolemic humans |journal=J Am Coll Nutr |volume=21 |issue=5 |pages=428–33 |year=2002 |month=October |pmid=12356785 |doi= |url=http://www.jacn.org/cgi/pmidlookup?view=long&pmid=12356785}}</ref>
===Type 2 diabetes===
Glucomannan may be useful as a therapeutic adjunct for type 2 diabetes. It has been shown to improve the lipid profile and alleviate the fasting [[blood glucose]] levels of type 2 diabetics.<ref>{{cite journal |author=Chen HL, Sheu WH, Tai TS, Liaw YP, Chen YC |title=Konjac supplement alleviated hypercholesterolemia and hyperglycemia in type 2 diabetic subjects--a randomized double-blind trial |journal=J Am Coll Nutr |volume=22 |issue=1 |pages=36–42 |year=2003 |month=February |pmid=12569112 |doi= |url=http://www.jacn.org/cgi/pmidlookup?view=long&pmid=12569112}}</ref>
==Commercial use==
As a [[food additive]], glucomannan is used as an [[emulsifier]] and [[thickener]]. It has [[E number]] E425(ii). Glucomannan also makes up the majority of [[shirataki noodles]].
==Dietary supplements==
Glucomannan is an ingredient in a variety of [[dietary supplement]] products marketed via [[television]] [[advertisement]]s claiming to aid in [[weight loss]]. According to the FTC, there is no clinical data supporting many of the claims<ref>[http://www.ftc.gov/opa/2004/06/dietsupp.shtm Ads for Various Diet Supplements and Topical Gels Don’t Cut the Fat, Says the FTC], Federal Trade Commission</ref><ref>[http://www.cfsan.fda.gov/~dms/qa-nut4.html What are some of the questionable weight loss products?], United States Food and Drug Administration</ref> and several companies have been determined by the FTC or the FDA to have violated the [[Federal Food, Drug, and Cosmetic Act]] including Vitacost,<ref>[http://www.fda.gov/cder/warn/cyber/2005/CL142e.pdf Food and Drug Administration letter]</ref> PediaLean,<ref>[http://www.ftc.gov/os/adjpro/d9318/0023300part3cmp040616.pdf Federal Trade Commission complaint]</ref> Herbal Worldwide Holdings,<ref>[http://www.ftc.gov/os/1998/09/9723157.cmp.htm Federal Trade Commission complaint]</ref> BioTrim,<ref>[http://www.ftc.gov/os/caselist/0323238/041109cmp0323238.pdf Federal Trade Commission letter]</ref> and others. The company Obesity Research Institute, the marketer of FiberThin, 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.<ref>[http://www.ftc.gov/opa/2005/06/fiberthin.shtm FTC Settles Claims with Marketers of FiberThin and Propolene], Federal Trade Commission</ref>
In 2002, a number of products containing konjac-derived glucomannan were recalled as choking hazards.<ref>[http://www.fda.gov/oc/po/firmrecalls/topics/konjac.html U.S. FDA Konjac Candy Recalls] - U.S. [[FDA]] konjac or glucomannan containing candy concerns and recalls</ref>
==References==
{{reflist}}
==External links==
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* [http://www.pdrhealth.com/drug_info/nmdrugprofiles/nutsupdrugs/glu_0121.shtml PDRhealth.com Glucomannan Studies] Glucomannan studies, with information on side effects.
[[Category:Polysaccharides]]
[[Category:Edible thickening agents]]
[[Category:Gums]]
[[fr:Glucomannane]]
[[ja:グルコマンナン]]