Glucomannan

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Glucomannan is a water-soluble polysaccharide that is considered a dietary fiber. It is a hemicellulose component in the cell walls of some plant species. Glucomannan is a food additive used as an emulsifier and thickener. The U.S. Food and Drug Administration (FDA) has not approved any product containing glucomannan for the treatment of any medical condition and its use may be harmful. They are also used to supplement animal feed for farmed animals.

Chemistry[edit]

Glucomannan is mainly a straight-chain polymer, with a small amount of branching. The component sugars are β-(1→4)-linked D-mannose and D-glucose in a ratio of 1.6:1.[1] The degree of branching is about 8% through β-(1→6)-glucosyl linkages.[2]

Glucomannan with α-(1→6)-linked galactose units in side branches is called galactoglucomannan.[citation needed]

Biological function[edit]

In the yeast cell 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 of Saccharomyces cerevisiae cell wall.[3]

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.[4][5]

This specific combination of various functionalities involves mannan oligosacharides-protein conjugates and highly hydrophilic and structurally variable 'brush-like' mannan oligosaccharides structures that can fit to various receptors of animal digestive tracts,[6] and to the receptors on the surface of bacterial membranes,[7] impacts these molecules bioactivity. Mannan oligosacharides-protein conjugates are involved in interactions with the animal's immune system and as result enhance immune system activity.[8] They also play a role in animal antioxidant and antimutagenic defense.[9]

Natural sources[edit]

Glucomannan comprises 40% by dry weight of the roots, or corm, of the konjac plant. Another culinary source is salep, ground from the roots of certain orchids and used in Turkish cuisine. Glucomannan is also a hemicellulose that is present in large amounts in the wood of conifers and in smaller amounts in the wood of dicotyledons.[citation needed] Glucomannan is also a constituent of bacterial, plant and yeast cell wall with differences in the branches or glycosidic linkages in the linear structure.[10][11][12]

Uses[edit]

Human food additive[edit]

Glucomannan is a food additive used as an emulsifier and thickener with the E number E425(ii).[13][14]

Human dietary supplement[edit]

Glucomannan is an ingredient in a variety of dietary supplement products marketed with claims that they aid in weight loss, but medical research has found no good evidence to support its use for this purpose.[15][16][17] 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.


Health risks[edit]

A health advisory was released by Health Canada stating 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 should not be taken immediately before going to bed."[18] The health advisory was issued after authorization of some products containing glucomannan for the purposes of appetite reduction, weight management, treatment of constipation and management of high cholesterol levels.[citation needed]

Consumer issues[edit]

Several companies have been determined by the Federal Trade Commission (FTC) or the Food and Drug Administration (FDA) to have, at some time, violated the Federal Food, Drug, and Cosmetic Act.[19] The companies include Vitacost,[20] PediaLean,[21] Herbal Worldwide Holdings,[22] BioTrim,[23] 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.[24]

In 2011, a number of jelly-type candy products containing konjac-derived glucomannan were barred from import by the US Food and Drug Administration due to choking hazards.[25]

Dietary supplements for animals[edit]

It is also used as dietary supplement for farmed animals in order to enable more efficient use of feed, called the feed conversion ratio. The effect of MOS on animal performance was analysed in meta-analyses for poultry,[26][27][28][29] pigs,[30][31] and calves.[32]

References[edit]

  1. ^ Kaname Katsuraya; Kohsaku Okuyamab; Kenichi Hatanakab; Ryuichi Oshimab; Takaya Satoc; Kei Matsuzakic (2003). "Constitution of konjac glucomannan: chemical analysis and 13C NMR spectroscopy". Carbohydrate Polymers. 53 (2): 183–189. doi:10.1016/S0144-8617(03)00039-0. 
  2. ^ "Glucomannan: Uses, Side Effects, Interactions and Warnings". 
  3. ^ Stewart, GG; Russell, I (1998). "Brewer's Yeast". Brewing Science & Technology Series III. The Institute of Brewing, London. 
  4. ^ Lesage, G.; Bussey, H. (2006). "Cell Wall Assembly in Saccharomyces cerevisiae". Microbiology and Molecular Biology Reviews. 70 (2): 317–43. doi:10.1128/MMBR.00038-05. PMC 1489534Freely accessible. PMID 16760306. 
  5. ^ Vinogradov, E; Petersen, B; Bock, K (1998). "Discussion". Carbohydrate Research. 307 (1–2): 177–83. doi:10.1016/S0008-6215(98)00042-1. PMID 9658572. 
  6. ^ Mansour, Michael K.; Levitz, Stuart M. (2003). "Fungal Mannoproteins: the Sweet Path to Immunodominance". ASM News. 69 (12): 595–600. 
  7. ^ Garofalo, Corinne; Wellens, Adinda; Nguyen, Hien; Van Gerven, Nani; Slättegård, Rikard; Hernalsteens, Jean-Pierre; Wyns, Lode; Oscarson, Stefan; et al. (2008). Zhang, Shuguang, ed. "Intervening with Urinary Tract Infections Using Anti-Adhesives Based on the Crystal Structure of the FimH–Oligomannose-3 Complex". PLoS ONE. 3 (4): e2040. doi:10.1371/journal.pone.0002040. PMC 2323111Freely accessible. PMID 18446213.  open access publication – free to read
  8. ^ Wismar, René; Brix, Susanne; Frøkiaer, Hanne; Laerke, Helle Nygaard (2010). "Dietary fibers as immunoregulatory compounds in health and disease". Annals of the New York Academy of Sciences. 1190: 70–85. doi:10.1111/j.1749-6632.2009.05256.x. PMID 20388138. 
  9. ^ Krizkova, L; Zitnanova, I; Mislovicova, D; Masarova, J; Sasinkova, V; Durackova, Z; Krajcovic, J (2006). "Antioxidant and antimutagenic activity of mannan neoglycoconjugates: Mannan–human serum albumine and mannan–penicillin G acylase". Mutation Research/Genetic Toxicology and Environmental Mutagenesis. 606: 72–9. doi:10.1016/j.mrgentox.2006.03.003. 
  10. ^ Elbein, A. D. (1969). Biosynthesis of a cell wall glucomannan in mung bean seedlings. Journal of Biological Chemistry, 244(6), 1608-1616.
  11. ^ Tokoh, C., Takabe, K., Sugiyama, J., & Fujita, M. (2002). CP/MAS 13C NMR and electron diffraction study of bacterial cellulose structure affected by cell wall polysaccharides. Cellulose, 9(3-4), 351-360.
  12. ^ Chorvatovičová, D., Machová, E., Šandula, J., & Kogan, G. (1999). Protective effect of the yeast glucomannan against cyclophosphamide-induced mutagenicity. Mutation Research/Genetic Toxicology and Environmental Mutagenesis, 444(1), 117-122.
  13. ^ Current EU approved additives and their E Numbers, Food Standards Agency, 26 November 2010
  14. ^ "E425(ii) Konjac Glucomannan". CyberColloids. Retrieved January 25, 2013.
  15. ^ Onakpoya I, Posadzki P, Ernst E (2014). "The efficacy of glucomannan supplementation in overweight and obesity: a systematic review and meta-analysis of randomized clinical trials". J Am Coll Nutr. 33 (1): 70–8. doi:10.1080/07315724.2014.870013. PMID 24533610. 
  16. ^ Zalewski, Bartłomiej M.; Chmielewska, Anna; Szajewska, Hania (March 2015). "The effect of glucomannan on body weight in overweight or obese children and adults: a systematic review of randomized controlled trials". Nutrition. 31 (3): 437–442.e2. doi:10.1016/j.nut.2014.09.004. ISSN 1873-1244. PMID 25701331. 
  17. ^ Allison, David B.; Zalewski, Bartłomiej M.; Chmielewska, Anna; Szajewska, Hania; Li, Peng; Goldsby, TaShauna U.; Keithley, Joyce K (2015). "Correction of data errors and reanalysis of "The effect of glucomannan on body weight in overweight or obese children and adults: A systematic review of randomized controlled trials"". Nutrition. 31 (7-8): 1056–1057. doi:10.1016/j.nut.2015.02.008. ISSN 0899-9007. PMC 4868090Freely accessible. PMID 26059384. 
  18. ^ "Health Canada Advises Canadians that Natural Health Products containing Glucomannan May Cause Serious Choking if Used with Insufficient Fluid". Health Canada. January 29, 2010. Archived from the original on 4 February 2010. 
  19. ^ "Ads for Various Diet Supplements and Topical Gels Don’t Cut the Fat, Says the FTC". Federal Trade Commission
  20. ^ Food and Drug Administration letter
  21. ^ C. Landis Plummer (June 15, 2004). DOCKET NO. 9318 Archived 2008-05-13 at the Wayback Machine.. Federal Trade Commission.
  22. ^ Federal Trade Commission complaint
  23. ^ Kovacic, William E.; Chun, Barbara Y.K. (November 3, 2004). "COMPLAINT FOR PERMTLNENT INJUNCTION AND OTHER EQUITABLE RELIEF". United States District Court for the Central District of California.
  24. ^ "FTC Settles Claims with Marketers of FiberThin and Propolene". Federal Trade Commission. June 20, 2005
  25. ^ "Import Alert 33-15, Detention Without Physical Examination of Gel Candies Containing Konjac" US FDA, Retrieved April 1, 2016
  26. ^ Hooge, Danny M. (2004). "Meta-analysis of Broiler Chicken Pen Trials Evaluating Dietary Mannan Oligosaccharide, 1993-2003". International Journal of Poultry Science. 3 (3): 163–74. doi:10.3923/ijps.2004.163.174. 
  27. ^ Rosen, G. D. (2007). "Holo-analysis of the efficacy of Bio-Mos® in broiler nutrition". British Poultry Science. 48 (1): 21–6. doi:10.1080/00071660601050755. PMID 17364536. 
  28. ^ Hooge, Danny M. (2004). "Turkey Pen Trials with Dietary Mannan Oligosaccharide: Meta-analysis, 1993-2003". 3 (3): 179–88. 
  29. ^ Rosen, G. D. (2007). "Holo-analysis of the efficacy of Bio-Mos® in turkey nutrition". British Poultry Science. 48 (1): 27–32. doi:10.1080/00071660601050730. PMID 17364537. 
  30. ^ Miguel, Jennifer C.; Rodriguez-Zas, Sandra L.; Pettigrew, James E. (2004). "Efficacy of a mannan oligosaccharide (Bio-Mos®) for improving nursery pig performance". Journal of Swine Health and Production. 12 (6): 296–307. 
  31. ^ Rosen, G. D. (2007). "Holo-analysis of the efficacy of Bio-Mos® in pig nutrition". Animal Science. 82 (5): 683–9. doi:10.1079/ASC200684. 
  32. ^ "Mannan Oligosaccharides: Natural Alternatives for Animal Nutrition (Part 3)" (PDF) (Press release). Milk Products. 2007. Retrieved April 5, 2011. 

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