Glucomannan

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"Propolene" redirects here. It is not to be confused with propylene.

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. Products containing glucomannan, marketed under a variety of brand names, are also sold as nutritional supplements for constipation, obesity, high cholesterol, acne vulgaris and type 2 diabetes. Although 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. Health Canada has authorized some products containing glucomannan for the purposes of appetite reduction, weight management, treatment of constipation and management of high cholesterol levels.

Chemistry

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.[citation needed]

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

Natural sources

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.[2][3][4]

Potential health benefits

Treatment of 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.[5] In the treatment of chronic constipation, glucomannan significantly improved symptoms of constipation while being well-tolerated and free of relevant side effects.[6]

Cholesterol and other lipids

Glucomannan has demonstrated statistically significant improvements in the total cholesterol of obese patients.[7] In healthy men, four weeks of taking 3.9 grams per day of glucomannan decreased total cholesterol, low-density lipoprotein, triglycerides, and systolic blood pressure; notably, triglycerides dropped by 23%.[8] Glucomannan has also been tested in children with high cholesterol in conjunction with a diet. A gender difference has been shown, greater decreases in total cholesterol and low-density lipoprotein were observed in girls when compared to boys.[9] When used in conjunction with chitosan, glucomannan decreases serum cholesterol, possibly by increasing steroid excretion via the feces.[10]

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.[11] Glucomannan also helps to increase insulin sensitivity and improves glycemia and risk factor for coronary heart disease [12]

Weight loss

Clinical trials examining the use of glucomannan for weight loss have produced mixed results.[13][14][15] A 2014 systematic review and meta-analysis of clinical trials failed to show that glucomannan supplementation generated statistically significant weight loss.[16]

Potential health risks

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 to Canadians 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."[17] 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

Several companies selling products containing glucomannan have been disciplined by the U.S. Federal Trade Commission (FTC) for misleading or exaggerated claims pertaining to the health benefits of glucomannan supplements.[18]

Glucomannan is an ingredient in a variety of dietary supplement products marketed via television advertisements claiming to aid in weight loss. According to the FTC, there is no clinical data supporting many of the manufacturer claims and 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. The companies include Vitacost,[19] PediaLean,[20] Herbal Worldwide Holdings,[21] BioTrim,[22] 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.[23]

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.[24]

Commercial use

Glucomannan is a food additive used as an emulsifier and thickener with the E number E425(ii).[25][26]

References

  1. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  2. ↑ Elbein, A. D. (1969). Biosynthesis of a cell wall glucomannan in mung bean seedlings. Journal of Biological Chemistry, 244(6), 1608-1616.
  3. ↑ 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.
  4. ↑ 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.
  5. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  6. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  7. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  8. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  9. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  10. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  11. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  12. ↑ Vuksan, V. L. A. D. I. M. I. R., et al. "Konjac-mannan (glucomannan) improves glycemia and other associated risk factors for coronary heart disease in type 2 diabetes. A randomized controlled metabolic trial." Diabetes Care 22.6 (1999): 913-919.
  13. ↑ Lua error in package.lua at line 80: module 'strict' not found.
  14. ↑ name="Walsh"
  15. ↑ JK. Keithley,J., Swanson, B., Mikolaitis, M., DeMeo, J., Zeller, L., Fogg, Adamji, J. 2013. Safety and Efficacy of Glucomannan for Weight Loss in Overweight and Moderately Obese Adults. J Obes. 2013; 2013: 610908
  16. ↑ 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. 2014;33(1):70-8.
  17. ↑ Health Canada Advises Canadians that Natural Health Products containing Glucomannan May Cause Serious Choking if Used with Insufficient Fluid, Health Canada Advisory
  18. ↑ "Ads for Various Diet Supplements and Topical Gels Don’t Cut the Fat, Says the FTC". Federal Trade Commission
  19. ↑ Food and Drug Administration letter
  20. ↑ C. Landis Plummer (June 15, 2004). DOCKET NO. 9318. Federal Trade Commission.
  21. ↑ Federal Trade Commission complaint
  22. ↑ 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.
  23. ↑ "FTC Settles Claims with Marketers of FiberThin and Propolene". Federal Trade Commission. June 20, 2005
  24. ↑ "Import Alert 33-15, Detention Without Physical Examination of Gel Candies Containing Konjac" US FDA, Retrieved April 1, 2016
  25. ↑ Current EU approved additives and their E Numbers, Food Standards Agency, 26 November 2010
  26. ↑ "E425(ii) Konjac Glucomannan". CyberColloids. Retrieved January 25, 2013.

External links

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