Document Detail

Human milk oligosaccharides are resistant to enzymatic hydrolysis in the upper gastrointestinal tract.
MedLine Citation:
PMID:  10837303     Owner:  NLM     Status:  MEDLINE    
BACKGROUND: Human milk oligosaccharides (HMOs) show a complexity and variety not found in milk of any other species. Although progress has been made in the past 3 decades with regard to identification and structural characterization of HMOs, not much is known about the physiologic functions of HMOs. OBJECTIVE: As a prerequisite for biological activity in infant metabolism, HMOs have to resist enzymatic hydrolysis in the gastrointestinal tract. To assess the extent to which selected HMOs are hydrolyzed, we carried out in vitro digestion studies using enzyme preparations of human and porcine pancreas and intestinal brush border membranes (BBMs). DESIGN: Fractions of HMOs, including structurally defined isolated oligosaccharides, were digested for up to 20 h with human pancreatic juice and BBMs prepared from human or porcine intestinal tissue samples. HMOs were incubated by using a porcine pancreatic homogenate and BBMs as enzyme sources. HMOs and digestion products were identified by mass spectrometry and anion-exchange chromatography. Additionally, free D-glucose, L-fucose, and N-acetylneuraminic acid were determined enzymatically. RESULTS: Whereas maltodextrin (control) was rapidly and completely hydrolyzed, neutral and acidic HMOs showed a profound resistance against pancreatic juice and BBM hydrolases. However, cleavage of most of the HMOs was achieved by using a pancreatic homogenate containing intracellular, including lysosomal, enzymes in addition to secreted enzymes. CONCLUSIONS: The results of this study strongly suggest that HMOs are not hydrolyzed by enzymes in the upper small intestine. Although intact HMOs may be absorbed, we postulate that a majority of HMOs reach the large intestine, where they serve as substrates for bacterial metabolism. Therefore, HMOs might be considered the soluble fiber fraction of human milk.
M B Engfer; B Stahl; B Finke; G Sawatzki; H Daniel
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  The American journal of clinical nutrition     Volume:  71     ISSN:  0002-9165     ISO Abbreviation:  Am. J. Clin. Nutr.     Publication Date:  2000 Jun 
Date Detail:
Created Date:  2000-07-14     Completed Date:  2000-07-14     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0376027     Medline TA:  Am J Clin Nutr     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1589-96     Citation Subset:  AIM; IM    
Institute of Nutritional Sciences, University of Giessen, Germany.
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MeSH Terms
Chromatography, Ion Exchange
Digestive System / enzymology*
Intestines / ultrastructure
Microvilli / enzymology
Milk, Human / chemistry*
Oligosaccharides / metabolism*
Pancreatic Juice / enzymology
Polysaccharides / metabolism
Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
Reg. No./Substance:
0/Oligosaccharides; 0/Polysaccharides; 9050-36-6/maltodextrin

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