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Galactooligosaccharide

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Galactooligosaccharide
Identifiers
ChEBI
Properties
(C6H10O5)n
Molar mass Variable
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Galactooligosaccharides (GOS), also known as oligogalactosyllactose, oligogalactose, oligolactose or transgalactooligosaccharides (TOS), belong to the group of prebiotics. Prebiotics are defined as non-digestible food ingredients that beneficially affect the host by stimulating the growth and/or activity of beneficial bacteria in the colon. GOS occurs in commercially available products such as food for both infants and adults.

Chemistry

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The composition of the galactooligosaccharide fraction varies in chain length and type of linkage between the monomer units. Galactooligosaccharides are produced through the enzymatic conversion of lactose, a component of bovine milk.

A range of factors come into play when determining the yield, style, and type of GOS produced. These factors include:

  • enzyme source
  • enzyme dosage
  • feeding stock (lactose) concentration
  • origins of the lactose
  • process involved (e.g. free or immobilized enzyme)
  • reaction conditions impacting the processing situation
  • medium composition

GOS generally comprise a chain of galactose units that arise through consecutive transgalactosylation reactions, with a terminal glucose unit. However, where a terminal galactose unit is indicated, hydrolysis of GOS formed at an earlier stage in the process has occurred. The degree of polymerization of GOS can vary quite markedly, ranging from 2 to 8 monomeric units, depending mainly on the type of the enzyme used and the conversion degree of lactose.

Digestion research

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Main article: Dietary fiber § Activity in the gut

Because of the configuration of their glycosidic bonds, galactooligosaccharides largely resist hydrolysis by salivary and intestinal digestive enzymes.[1] Galactooligosaccharides are classified as prebiotics, defined as non-digestible food ingredients as substrate for the host by stimulating the growth and activity of bacteria in the colon.[1]

The increased activity of colonic bacteria results in various effects, both directly by the bacteria themselves or indirectly by producing short-chain fatty acids as byproducts via fermentation. Examples of effects are stimulation of immune functions, absorption of essential nutrients, and synthesis of certain vitamins.[2][3][4]

Stimulating bacteria

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Galactooligosaccharides are a substrate for bacteria, such as Bifidobacteria and lactobacilli. Studies with infants and adults have shown that foods or drinks enriched with galactooligosaccharides result in a significant increase in Bifidobacteria.[1] These sugars can be found naturally in human milk, known as human milk oligosaccharides.[5] Examples include lacto-N-tetraose, lacto-N-neotetraose, and lacto-N-fucopentaose.[6]

Immune response

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Human gut microbiota play a key role in the intestinal immune system.[1] Galactooligosaccharides (GOS) support natural defenses of the human body via the gut microflora,[7] indirectly by increasing the number of bacteria in the gut and inhibiting the binding or survival of Escherichia coli, Salmonella typhimurium and Clostridia.[8][9] GOS can positively influence the immune system indirectly through the production of antimicrobial substances, reducing the proliferation of pathogenic bacteria.[10][11]

Constipation

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Constipation is a potential problem, particularly among infants, elderly and pregnant women. In infants, formula feeding may be associated with constipation and hard stools.[12] Galactooligosaccharides may improve stool frequency and relieve symptoms related to constipation.[13]

See also

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References

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  1. ^ a b c d Jeurink, P. V; Van Esch, B. C; Rijnierse, A; Garssen, J; Knippels, LM (2013). "Mechanisms underlying immune effects of dietary oligosaccharides". American Journal of Clinical Nutrition. 98 (2): 572S–7S. doi:10.3945/ajcn.112.038596. PMID 23824724.
  2. ^ Gibson GR (October 1998). "Dietary modulation of the human gut microflora using prebiotics". British Journal of Nutrition. 80 (4): S209–12. doi:10.1017/S0007114500006048. PMID 9924286.
  3. ^ Roberfroid MB (June 2000). "Prebiotics and probiotics: are they functional foods?". American Journal of Clinical Nutrition. 71 (6 Suppl): 1682S–7S, discussion 1688S–90S. doi:10.1093/ajcn/71.6.1682S. PMID 10837317.
  4. ^ Macfarlane GT, Steed H, Macfarlane S (February 2008). "Bacterial metabolism and health-related effects of galacto-oligosaccharides and other prebiotics". Journal of Applied Microbiology. 104 (2): 305–44. doi:10.1111/j.1365-2672.2007.03520.x. PMID 18215222. S2CID 205319925.
  5. ^ "Human Milk Oligosaccharides". NNI Global Website. Archived from the original on 2017-09-19. Retrieved 2020-12-04.
  6. ^ Miesfeld, Roger L. (July 2017). Biochemistry. McEvoy, Megan M. (First ed.). New York, NY. ISBN 978-0-393-61402-2. OCLC 952277065.{{cite book}}: CS1 maint: location missing publisher (link)
  7. ^ Gibson G.R.; McCartney A.L.; Rastall R.A. (2005). "Prebiotics and resistance to gastrointestinal infections". Br. J. Nutr. 93 (Suppl. 1): 31–34. doi:10.1079/BJN20041343. PMID 15877892.
  8. ^ Shoaf K.; Muvey G.L.; Armstrong G.D.; Hutkins R.W. (2006). "Prebiotic galactooligosaccharides reduce adherence of enteropathogenic Escherichia coli to tissue culture cells". Infect Immun. 74 (12): 6920–8. doi:10.1128/iai.01030-06. PMC 1698067. PMID 16982832.
  9. ^ Sinclair HR, et al. (2009). "Galactooligosaccharides (GOS) inhibit Vibrio cholerae toxin binding to its GM1 receptor". Journal of Agricultural and Food Chemistry. 57 (8): 3113–3119. doi:10.1021/jf8034786. PMID 19290638.
  10. ^ Macfarlane GT, Steed H, et al. (2008). "Bacterial metabolism and health-related effects of galacto-oligosaccharides and other prebiotics". Journal of Applied Microbiology. 104 (2): 305–344. doi:10.1111/j.1365-2672.2007.03520.x. PMID 18215222. S2CID 205319925.
  11. ^ Vos AP, M'Rabet L, et al. (2007). "Immune-modulatory effects and potential working mechanisms of orally applied nondigestible carbohydrates". Critical Reviews in Immunology. 27 (2): 97–140. doi:10.1615/critrevimmunol.v27.i2.10. PMID 17725499.
  12. ^ Scholtens, P. A; Goossens, D. A; Staiano, A (2014). "Stool characteristics of infants receiving short-chain galacto-oligosaccharides and long-chain fructo-oligosaccharides: A review". World Journal of Gastroenterology. 20 (37): 13446–13452. doi:10.3748/wjg.v20.i37.13446. PMC 4188896. PMID 25309075.
  13. ^ Yu, T; Zheng, Y. P; Tan, J. C; Xiong, W. J; Wang, Y; Lin, L (2017). "Effects of Prebiotics and Synbiotics on Functional Constipation". The American Journal of the Medical Sciences. 353 (3): 282–292. doi:10.1016/j.amjms.2016.09.014. PMID 28262216.
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