Authors:
S. Phoon and N Manolios
Article used with permission.
Abstract
Glucosamine is a modified sugar (see Figure 1)2 that is formed
by the human body and used as a precursor to form larger molecules
called glycosaminoglycans, which are involved in the formation
and repair of cartilage. These repeating sugar units are also
a major constituent of bones, ligaments, tendons and fluid
in the joint. Because of their low compressibility they are
ideal lubricants and are used as shock absorbers by joints.
It is believed that synthetically produced and ingested glucosamine
may be beneficial in correcting the imbalance between production
and destruction of naturally occurring glucosamine in osteoarthritis
cartilage, thereby repairing damaged joints.
There are a multitude of brands available over the counter
(see Table 1)3. There are two chemical forms available, glucosamine
sulphate (Arthro-Aid Direct, Bioglan, Blackmores, Arthrogen,
GoldenGlow, Healthstream and Procosamine); and glucosamine
hydrochloride (Arthro-Aid and Osteo-Eze). The most commonly
studied has been glucosamine sulphate. Glucosamine has been
administered in a variety of ways, such as a topical cream,
an oral tablet, an intra-muscular injection, and as an intra-articular
injection (that is directly into the joint). Both types of
glucosamine tablets are supplied in doses of 400 to 1000mg.
The recommended dose of glucosamine is 1 to 2 tablets per
day. In research studies the dose most commonly tested has
been 1500mg per day. After taking a tablet of glucosamine,
the concentration peaks in the blood stream at 4 hours, and
slowly declines over 24 hours. When a radioactively labelled
forms of glucosamine were used in experiments, it was shown
to be actively taken up in skeletal tissue such as cartilage
and bone. It was also noted to be found in other tissues,
particularly liver and kidney, although its role in these
organs is less clear4.
Osteoarthritis or degenerative joint disease is the common
type of arthritis. It usually affects middle-aged and elderly,
and is characterized by the breakdown of cartilage (Figure
3, Figure 4). Cartilage is responsible for providing the "shock-absorption"
at the end of bones, and it is the loss of this cushioning
effect due to the loss of glycosaminoglycans that results
in pain and loss of range of movement. Osteoarthritis may
be diagnosed by clinical examination or by X-rays. Up till
now, the focus of treatment has revolved around medication
to relieve symptoms such as pain and the protection of the
joint. These have included aspirin, paracetamol and non-steroidal
anti-inflammatory drugs (NSAIDS). The major concern with NSAIDS
is the risk of upper gastro-intestinal side effects, particularly
bleeding stomach ulcers. The new Cox-II inhibitors (Vioxx
and  )
have since reduced the gastro-intestinal side effects.
There are a large number of studies using glucosamine that
have been reported to show a symptomatic improvement in flexibility.
Pooling all of these studies together, researchers have used
a technique called meta-analysis to combine similar well-designed
studies to determine whether or not there is a real effect.
This is particularly useful in combining many small studies
with smaller numbers of patients. All 3 meta-analyses have
reported an improvement with glucosamine for the easing of
joint discomfort using various measures of pain 9-12. Unfortunately
there were a number of criticisms in the quality of these
smaller studies. These include lack of standardization, insufficient
information in the design of the study, and a failure to adequately
conceal the treatment from the placebo. Nevertheless, glucosamine
had been shown to improve symptoms of joint discomfort against
placebo.
Continue
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Be sure to visit the Glucosamine Product Guide for a review of commercially available glucosamine products broken down by 9 different categories such as price per month, quality and type. Learn what the best products out there are and what criteria was used to ranked each. |
