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Glucosamine Effects in Humans: A Review of Effects on Glucose Metabolism, Side Effects,
Safety Considerations, and Efficacy
James W. Anderson, MD
University of Kentcuky
Lexington, KY
Safety Considerations, and Efficacy
James W. Anderson, MD
University of Kentcuky
Lexington, KY
Glucosamine, 2-amino-2-deoxy-D-glucose, is an amino monosaccharide that is an
essential component of mucopolysaccharides and chitin. Glycosaminoglycans, or
mucopolysaccharides, are large complexes of negatively-charged carbohydrate chains that are
incorporated into mucous secretions, connective tissue, skin, tendons, ligaments and cartilage.
Glucosamine and its acetylated derivative, N-acetylglucosamine, are readily synthesized in the
body from glucose. Because of its high concentration in joint tissues, the hypothesis that
glucosamine supplements would provide symptomatic relief for osteoarthritis was developed
more than 30 years ago.(1) Many clinical trials have tested this hypothesis(2) and glucosamine
supplements are widely used to relieve arthritic complaints.(3)
To meet the demand for glucosamine nutritional supplements, three forms of
glucosamine are commonly available: glucosamine hydrochloride, glucosamine sulfate, and N-acetyl-
glucosamine. These glucosamine compounds are generally derived from chitin, a
biopolymer present in the exoskeleton of marine invertebrate animals. The glucosamine derived
from chitin in the cell walls of many fungi appears to be chemically identical to that found in
marine invertebrates.(2)
Glucosamine directly enters into the hexosamine biosynthetic pathway. There is
disagreement as to the presence of any undesired side effects of this exogenous glucosamine in
animal systems.(site references if you believe necessary) Some, but not all, studies in animals
suggest that glucosamine administration may produce insulin resistance and hyperglycemia by
affecting insulin secretion and action.(2;4) However, most in vitro and animal studies have
achieved blood and tissue levels 250 to 2500 times higher than would be expected with
glucosamine doses used in humans.(4-7) Thus, it is important to rigorously review available data
in humans to assess the effects of glucosamine intake on glucose homeostasis. Glucosamine is
usually taken orally, as opposed to intra-arterially or intramuscularly, and 90% is absorbed.(8)
Orally administered glucosamine has only 26% the bioavailability of intravenously administered
glucosamine.(9) A significant fraction of orally administered glucosamine undergoes first-pass
metabolism in the liver.(9) Blood levels achieved after oral glucosamine are only 20% those
achieved with intravenous glucosamine.(2;8)
This review will examine the available data from humans to assess the effects of
glucosamine on glucose metabolism. The effects of chronic glucosamine intake on blood
chemistries, hematologic parameters, urinanalysis, occult blood in the feces, blood pressure and
pulse rate will be tabulated. Side effects reported with glucosamine compared to placebo from
placebo-controlled trials will be compared. Finally, an overview of the efficacy of glucosamine
for arthritic complaints will be provided.
Materials and Methods
This review focuses on clinical studies performed with human subjects. The relevant
articles were identified by Medline search and by review of articles referenced in primary reports
and review articles. A previous review(2) and two meta-analyses(10;11) have performed detailed
essential component of mucopolysaccharides and chitin. Glycosaminoglycans, or
mucopolysaccharides, are large complexes of negatively-charged carbohydrate chains that are
incorporated into mucous secretions, connective tissue, skin, tendons, ligaments and cartilage.
Glucosamine and its acetylated derivative, N-acetylglucosamine, are readily synthesized in the
body from glucose. Because of its high concentration in joint tissues, the hypothesis that
glucosamine supplements would provide symptomatic relief for osteoarthritis was developed
more than 30 years ago.(1) Many clinical trials have tested this hypothesis(2) and glucosamine
supplements are widely used to relieve arthritic complaints.(3)
To meet the demand for glucosamine nutritional supplements, three forms of
glucosamine are commonly available: glucosamine hydrochloride, glucosamine sulfate, and N-acetyl-
glucosamine. These glucosamine compounds are generally derived from chitin, a
biopolymer present in the exoskeleton of marine invertebrate animals. The glucosamine derived
from chitin in the cell walls of many fungi appears to be chemically identical to that found in
marine invertebrates.(2)
Glucosamine directly enters into the hexosamine biosynthetic pathway. There is
disagreement as to the presence of any undesired side effects of this exogenous glucosamine in
animal systems.(site references if you believe necessary) Some, but not all, studies in animals
suggest that glucosamine administration may produce insulin resistance and hyperglycemia by
affecting insulin secretion and action.(2;4) However, most in vitro and animal studies have
achieved blood and tissue levels 250 to 2500 times higher than would be expected with
glucosamine doses used in humans.(4-7) Thus, it is important to rigorously review available data
in humans to assess the effects of glucosamine intake on glucose homeostasis. Glucosamine is
usually taken orally, as opposed to intra-arterially or intramuscularly, and 90% is absorbed.(8)
Orally administered glucosamine has only 26% the bioavailability of intravenously administered
glucosamine.(9) A significant fraction of orally administered glucosamine undergoes first-pass
metabolism in the liver.(9) Blood levels achieved after oral glucosamine are only 20% those
achieved with intravenous glucosamine.(2;8)
This review will examine the available data from humans to assess the effects of
glucosamine on glucose metabolism. The effects of chronic glucosamine intake on blood
chemistries, hematologic parameters, urinanalysis, occult blood in the feces, blood pressure and
pulse rate will be tabulated. Side effects reported with glucosamine compared to placebo from
placebo-controlled trials will be compared. Finally, an overview of the efficacy of glucosamine
for arthritic complaints will be provided.
Materials and Methods
This review focuses on clinical studies performed with human subjects. The relevant
articles were identified by Medline search and by review of articles referenced in primary reports
and review articles. A previous review(2) and two meta-analyses(10;11) have performed detailed
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